DESIGN GUIDELINES...14 om Fr pilot projects o t standard construction practices – passive ... Prolonged symptoms may lead to disability or, at worst, prevent the occupancy of buildings

DESIGN GUIDELINESTheoretical and practical information on ventilation

DESIGN GUIDELINESTheoretical and practical information on ventilation

Ensto Enervent OyKipinätie 1, FI-06150 Porvoo, FinlandTel. +358 207 528 800www.enervent.fi1st edition, 9/2014

Contents

All Enervent ventilation units can be dimensioned with the Energy Optimizer dimensioning software. The software can be used freely on Ensto Enervent’s website: www.enervent.fi.

1 Foreword ......................................................................................................................................... 6

2 What is indoor air? ................................................................................................................... 8

3 Tasks of ventilation ............................................................................................................... 12

4 Needs assessment helps in determining the design level .................. 24

5 The elements of a good ventilation system .................................................... 38

6 Pre- and after-heating solutions ................................................................................ 52

7 Control systems guarantee high-quality indoor air .................................. 56

8 Supply-air cooling/air conditioning ....................................................................... 68

9 Heat pumps ............................................................................................................................... 78

10 Comfortable and energy-efficient air heating ............................................... 84

11 Enervent CHG – Ventilation pre-heating and pre-cooling .................. 92

12 Pitfalls of design ...................................................................................................................... 96

13 Example cases – Enervent ventilation solutions

in various projects .............................................................................................................. 102

14 From pilot projects to standard construction practices – passive

and zero-energy houses will soon become mainstream .................. 122

References ................................................................................................................................ 130

FOREWORD

FOREWORD Congratulations! You are holding a new and significant manual in your hands. We have compiled this design manual for you, and we hope that it becomes a favorite for each and every HVAC professional – designers in particular. We trust that these guidelines provide useful information that will help in the understanding and design of room-spe-cific ventilation for modern single-family houses and other residential buildings.

Building services engineering solutions and construction in general have changed and developed in a few decades to the extent that even the industry professionals have difficulties in keeping up with the pace. The level of development has been especially high in the field of ventilation. Despite this, the most recent official regulations were issued over ten years ago. Moreover, these regulations are largely based on regulations, guidelines and methods of operation that are even older.

In the field of construction, people are used to relying on tried and tested meth-ods, materials and solutions that have proven their functionality for the longest time possible. However, the challenges that energy-efficient construction sets for ventilation, as well as our requirements and expectations regarding the functionality of building services engineering solutions, have changed to the extent that we cannot respond to them with outdated methods and knowledge.

Therefore, the field of construction needs clear, modern design guidelines that combine theoretical and practical information on ventilation in an easy-to-read format.

The challenges of ventilation in a changing environmentImproving the energy efficiency of new buildings and the existing building stock is one of the simplest ways to slow down climate change.

Designing buildings that are more airtight and better insulated is a demanding task. The old, well-proven rules on air flow rates, underpressure, make-up air and other compo-nents critical for the operation of ventilation are no longer valid.

In a building that is not airtight, air leaks provide make-up air where necessary, but in an airtight building the ventilation unit can be considered to be the lungs of the building, controlling practically all air that enters it. An airtight building does not forgive any design or installation mistakes, or allow use that differs from the designed use. Therefore, air flow rates that were based on experience no longer meet current use and construction requirements.

The more energy-efficient buildings we construct, the more important the flawless operation of the ventilation system and the building in general becomes. The zero-en-ergy level will pose even greater challenges for the operation and energy efficiency of ventilation units.

FOREWORD

The leap from the principle of removing stale air by natural ventilation via open windows and similar openings – a system that worked for thousands of years – to specifically designed mechanical ventilation and further to air conditioning, is a huge one. Adaptation has been made easier by the fact that air conditioning in cars is almost an obligatory feature for most of us. In addition to the replacement of air in accordance with the criteria set by the designer, air conditioning brings additional benefits: the cooling of indoor air as well as the control of carbon dioxide and humidity levels – that is, a controlled and good indoor climate.

Technological development and energy-efficient construction have brought air heating back as a viable option for new detached, semi-detached and terraced houses. Traditional massive heating systems are not necessary in an airtight passive house. Mod-ern air heating (and cooling) utilizes heat pump and circulation air. Indoor air quality is controlled with temperature sensors and carbon dioxide and humidity sensors.

In addition to energy efficiency, health and safety are also topical issues in construction. Nobody should live or work in a building that is sick. Our duty as professionals working in the construction and real estate sector is to make every effort to ensure that the new buildings are healthy – and to heal every possible building that has been deemed sick.

The most important task for ventilation is to ensure healthy and safe indoor air. Indoor air quality problems and exposure to mold are issues that should be resolved for good. That is something we as ventilation professionals have a say in. Life Cycle Man-agement (LCM) – correct design, installation, use and maintenance – is in the spotlight.

These are exciting times for the ventilation industry due to the current challenges and rapidly developing technical solutions. The health and safety of the buildings of the future, as well as the safety of the users and residents of those buildings, are largely in our hands.

With these design guidelines, we want to help you, valued reader, to achieve the best possible results and the highest possible customer satisfaction level in your work. We believe that we have succeeded in our goal when a satisfied customer or end user gives you positive feedback about your work as a designer and ventilation professional.

Happy reading!

WHAT IS INDOOR AIR?

Good indoor air is something that you don’t necessarily notice. You cannot see, smell, taste, hear, or feel it. You do not need to pay attention to good indoor air. But if you are exposed to bad indoor air, you will notice the difference immediately.

Climate is a familiar term for most of us, and everyone knows what it means – at least in principle. Indoor climate is a less familiar concept to the layman. It refers to the build-ing’s environmental factors that have an impact on human health and comfort.

These environmental factors include heat and moisture conditions, impurities and allergens in the air, electromagnetic fields, lighting conditions and noise.

Besides lighting, ventilation has an effect on every factor affecting the quality of indoor climate.

The regulations and guidelines in Section D2 of the National Building Code of Finland (later referred to as Section D2) relate to the indoor climate and ventilation of new buildings. With regard to holiday homes, the regulations only relate to buildings intend-ed for all-year-round or winter use.

“Ventilation means maintaining and enhancing indoor air quality by changing indoor air.” Section D2, 3.1.1

2.1 Indoor climate quality and healthIt is now widely understood that a poor indoor climate causes a variety of symptoms for many people. Prolonged symptoms may lead to disability or, at worst, prevent the occupancy of buildings where the indoor climate is impaired. The actual classification of diseases for people who have become sick due to poor indoor climate has not yet been agreed upon. The reason is that it is difficult to infallibly prove the link between exposure and symptoms. In any case, the problem is very real and many experts view that it is increasing rapidly.

The average human spends 90% of his or her life indoors and therefore breathes about 20 kilograms of indoor air – good or poor – per day.

The problems of poor indoor climate that are specifically related to ventilation include unpleasant odors due to mold growth, stuffy air, high carbon dioxide levels, draft dis-comfort and excessively high or low indoor temperature.

Some people are more sensitive to indoor climate problems than others. They are like the canaries that were used as air quality indicators in 19th century coal mines. When the bird stopped singing, it was time for the miners to quickly leave the mine. Therefore, we must take those symptoms that the people who are sensitive to indoor air quality experience seriously. The most common symptoms caused by poor indoor climate include respiratory problems, eye irritation, headaches and fatigue.

Section D2

Section D2 of the National Building Code of Finland (2003, updated in 2012) specifies the minimum requirements for the indoor climate and ventilation of buildings. By following these requirements, a satisfactory level of the indoor air classification (S3) is reached. It entitles the develop-er to a building permit but does not guarantee good indoor air quality. When building homes in particular, the best possible indoor air quality level – prefera-bly the highest level – should be aimed for.

WHAT IS INDOOR AIR?2

WHAT IS INDOOR AIR?

Eye, respiratory, mucous membrane and skin irritation can be caused by excessively high temperature, air that is too dry, formaldehyde and other organic gases, particulate impurities or bioaerosols.

Excessively high temperature, high carbon dioxide levels, organic gases or poor lighting conditions can be the cause of headaches, nausea, dizziness and fatigue.

When poor indoor air quality actually makes you sick, the situation is really bad. Clinical-ly observable diseases include allergic rhinitis and hypersensitivity pneumonitis, which can be caused by exposure to airborne mold spores. Moreover, cigarette smoke and radon gas can contribute to the risk of lung cancer.

Asthma and allergy symptoms are a significant problem for public health and also the national economy, because of the costs associated with absence from work due to sick-ness. Up to two-thirds of children suffer or have suffered from asthma and allergy symp-toms. Studies indicate that the indoor environment has a significant impact on people’s exposure to asthma and allergic symptoms. Its share of the total exposure is about 75%. Asthma and allergy symptoms are increased by poor ventilation, high air humidity level and high levels of moisture in structures, for example.

Fortunately, not all those who are exposed to indoor climate problems get sick but in any case, poor indoor climate has an impact on both mood and work efficiency.

“The building shall be designed and constructed as an entity in such a way that a healthy, safe and comfortable indoor climate can be achieved in the occupied zone under all normal weather conditions and operational situations.” Section D2, 2.2.1

2.2 Attention to temperatureA human being feels comfortable when his or her body is at a balanced temperature. This means that the human metabolism generates the same amount of heat that is transferred to the environment. This balanced temperature is always personal. An envi-ronment that is too warm for someone can be too cold for someone else. The average temperature that is experienced as most suitable by the majority of people in the winter is +20...22 °C. However, this is not suitable for everyone, and up to 30% of people may feel uncomfortable at the specified design room temperature. A frail older person may need to put on another sweater, whereas a robust bodybuilder may be sweating uncomfortably.

It would be best if everyone could set the temperature of the space they are occupying to correspond with their own preferences and habits.

“A temperature of +21 °C is normally used as the design room temperature for an occu-

WHAT IS INDOOR AIR?

pied zone during the heating season and…. a temperature of +23 °C is normally used as the design room temperature during summer.” Section D2, 2.2.1.1

Studies indicate that indoor air that is too warm increases the number of symptoms related to indoor air and can dry out atopic skin further. Keeping temperatures at proper levels is an excellent way to improve indoor climate, add comfort, and also reduce energy consumption.

The temperature should be kept as constant as possible. Air movement or air flow that is too fast can cause people to feel a draft, but it can also be caused by air or surface temperatures that are too low.

“The building shall be designed and constructed in such a way that air movement, ther-mal radiation and surface temperatures will not cause discomfort in the occupied zone during periods of use.” Section D2, 2.2.3

2.3 Ventilation to remove impuritiesWe, along with our pets, are responsible for a significant share of the impurities in indoor air. We release carbon dioxide, methane and aldehydes, among others. Of these substances, carbon dioxide is generally used as an indicator for human-originated impurities.

The human-originated impurities are removed from a space with sufficient ventilation. Ventilation should also be controlled on the basis of actual need.

“The building shall be designed and constructed in such a way that the indoor air does not contain any gases, particles or microbes in such quantities that are harmful to health, or any odors that reduce comfort.” Section D2, 2.3.1

“The maximum carbon dioxide concentration in indoor air under normal weather condi-tions and during occupancy is generally 2,160 mg/m3 (1,200 ppm).” Section D2, 2.3.1.1

Carbon dioxide is harmful to human health only in relatively high concentrations (over 5,000 ppm). In order to keep the carbon dioxide level even at a satisfactory level (below 1,500 ppm), the outdoor air flow per person should be about 6 liters per second. In addition to people, the required outdoor air flow is increased by any pets present in the buildings.

Stuffy indoor air is a problem, particularly in bedrooms. We recommend that a design air flow rate of 2 x 6 l/s is used for a one-child bedroom and 3 x 6 l/s for the master bedroom when designing basic ventilation (that is, separate cooling and heating). This way one is prepared for any changes during the life span of the building. The air flow rate can be decreased if the human load is lower (demand-controlled ventilation).

WHAT IS INDOOR AIR?

Basic ventilation also removes impurities originating from construction materials from the indoor air. Construction materials have a major impact on indoor air quality. To ensure the best indoor air quality possible, low-emitting materials of indoor air class S1 should be selected.

Normal construction materials do not usually cause serious problems, provided that they are used and applied correctly. However, impurities are released from all materials when they are new, so ventilation should be operated at a higher rate during the first year.

Ventilation should not be designed to remove impurities that can more reasonably be avoided by selecting another material, for example.

Often spaces have individual devices or functions that generate a lot of impurities and/or increase heat or moisture load. Such spaces include copy rooms in offices, and wet rooms and laundry rooms with laundry drying operations in homes, for example.

For the current air flow rates specified in Section D2, it has been assumed that laundry is dried either outdoors or in drying rooms. According to Section D2, the minimum air flow rate for bathrooms is 10 l/s, provided that the boosting reserve is 15 l/s. When designing air flow rates for the bathroom and drying room, the following air flow rates specified for common spaces in Section D2 can be used: bathroom 3 l/s/m2 and drying room 2 l/s/m2.

In a manual for ventilation technology from 1959, the recommended air flow rate for bathrooms was 17...27 l/s, and for drying rooms 83 l/s. These values are from an era when the moisture load was notably lower than it is today.

Normally, supply air is led into wet rooms from cleaner occupied spaces, in order to maintain indoor air quality that is as good as possible. However, the best results are achieved by room-specific supply and extract air ventilation. In commercial construc-tion, each source of impurities can be equipped with a separate hood to exhaust the impurities to the outdoors, for example.

Outdoor impurities bother people, especially when they are indoors. Impurities enter via windows and doors, but they are also carried in by the ventilation system and by infiltration. In urban areas, the biggest problem is caused by traffic-re-lated pollution, such as carbon monoxide, hydrocarbons, particles (soot) and nitrogen oxides. Industrial releases can cause problems in industrial areas. Organic particles such as pollen can be very bothersome, especially in the countryside and near parks.

The most efficient way to keep the indoor air free from outdoor impurities is to filter the outdoor air before letting it in. Dust and soot can also be removed if fine filters are used in addition to coarse filters. The purity of air in cleanrooms is ensured by activated carbon, ionizer, gas or HEPA filtering technology, but these are usually too expensive for normal spaces. They are necessary if the load caused by outdoor impurities is high.

TASKS OF VENTILATION


“The ventilation system shall be designed and constructed on the basis of the planned type of use and occupancy of the building in such a way that it will create conditions for a healthy, safe and comfortable indoor climate under normal weather and occupancy conditions” Section D2, 3.1.1

Ventilation plays a crucial role in making the indoor climate of a building healthy and comfortable.

Controlled ventilation ensures that there is a sufficient amount of clean air for breathing and that any impurities generated in the building are efficiently removed.

More than 15,000 liters of air pass through the human lungs each day.

From natural ventilation to air conditioningVentilation in a building is based on the pressure difference that is generated either mechanically by fans, or in natural ventilation by the combined effect of temperature and wind. In a supply and extract air system, supply air is also blown in mechanically, whereas in an extract air system, fans are used only for removing the exhaust air. An air conditioning system makes it possible to increase or decrease the supply air humidity level as well as cool or heat the supply air. By utilizing various sensors for measuring indoor air quality, indoor air can be kept at a predefined state of balance, regardless of changes in external conditions or use.

Natural ventilation was the most common method of ventilation until the end of the 1970s, especially due to its low investment costs. Natural ventilation is based on the pressure differences between the indoor and outdoor air caused by temperature and wind. Cooking often requires a separate, direct extract air solution.

Natural ventilation has its problems. The ventilation air flow varies by weather: the flow rates are highest in cold weather, and often insufficient in warm weather. The supply air is taken in directly, without cleaning or treating it in any way. Moreover, valuable heat energy is wasted by letting it out with the exhaust air.

Natural ventilation works relatively well in a well-built house of its time, provided that the room height is sufficient and the air inlet and outlet routes are properly designed and not blocked. Unfortunately, it is common that natural ventilation does not work as designed in old houses. Make-up air starts to infiltrate through the leaky structures. The more effort is made to seal the cold air leaks, the more difficult problems are created.

When the airtightness of a building equipped with natural ventilation is improved by installing new windows, for example, it may result in a situation where the amount of make-up air is not sufficient.

Sometimes obvious mistakes are made when renovating. These include the installation of incorrect terminal devices or horizontal ventilation ducts. This will increase the pres-sure difference and result in a duct that no longer has any draft.


Important terms

The efficiency of heat recovery is compared using temperature ratio and annual efficiency. The temperature ratio represents the heat recovery capacity of the actual heat recovery unit in a standardized test setting. The an-nual efficiency indicates the share of ventilation heating energy cov-ered by the heat recovery system. The annual efficiency takes the entire heating season, the location of the building and heat exchang-er frost protection into account.

A ventilation unit inevitably consumes electricity. The unit’s Specific Fan Power (SFP) reveals how much electricity its fans require for moving air. SFP can be improved by designing the ventilation system properly.

When an energy renovation is carried out on an old building, its ventilation must be redesigned. At this stage, the most energy-efficient option that also increases living comfort the most is a modern mechanical supply and extract air ventilation system.

Mechanical extract air ventilation started to become more popular in detached houses in the 1960s. It was introduced because natural ventilation did not quite work as de-sired. Houses were equipped with exhaust ductwork and a roof ventilator. The used air is removed by the ventilator, and the make-up air is usually taken in through make-up air vents fitted above windows. The problem was cold drafts experienced due to the cold incoming air. Because people then blocked up make-up air vents to reduce the un-comfortable drafts, the make-up air found alternative routes through various structures.

The main problem with mechanical extract air systems is very poor energy efficien-cy – even when they work as designed. The roof ventilator exhausts the costly heated air directly outdoors without showing any mercy. Because controlling the amount of make-up air accurately is difficult, the carbon dioxide content increases to excessively high levels if the space is occupied by a larger number of people.

When restoring an old building and making its structures more airtight, its ventilation system must also be thoroughly examined to ensure that the amount of make-up air is sufficient after the renovation. A modern mechanical supply and extract air ventilation system with highly efficient energy recovery properties is a profitable investment.

In fact, mechanical supply and extract air ventilation only increased in popularity in resi-dential building applications after the energy efficiency requirements were introduced.

As the design of buildings becomes more energy efficient, it becomes increasingly difficult to achieve the desired indoor climate quality levels without using mechanical ventilation or air conditioning. In terms of health, mechanical supply and extract air ventilation is highly beneficial due to the possibility to filter and treat the supply air effi-ciently, and energy efficiency is improved thanks to heat recovery from the extract air.

Modern buildings that are especially energy efficient need even more precise indoor cli-mate control than that offered by mechanical supply and extract air systems. The indoor conditions in air conditioned spaces are always constant regardless of the weather, time of the year, or use.

“Air conditioning means the control of air purity, temperature, humidity and movement of indoor air by processing the supply or circulation air.” Section D2, 1.3.1

Saving energy the wrong wayWhen in operation, a ventilation system inevitably consumes energy to provide a good and healthy indoor climate. A house, let alone the comfort of its residents, should never be sacrificed for saving energy by decreasing the ventilation rate. Efficient heat recovery uses energy that has already been purchased; this helps to keep the costs under control. The annual efficiency rate of heat recovery in systems equipped with a rotating heat


exchanger can be up to 80%. In a 140-m2 house with minimum-rate ventilation, this translates into a saving of almost 9,000 kWh in year.

Moreover, a demand-controlled ventilation system can prevent unnecessary use of energy. This means that the level and rate of ventilation or air conditioning is controlled according to the indoor temperature, carbon dioxide level or humidity level, for exam-ple.

Properly designed and used ventilation that utilizes the latest equipment and solutions is very energy efficient and consumes only a small amount of heating energy and electricity.

Specific Fan Power (SFP) represents the electricity consumption of a ventilation unit and system. When the SFP remains below 1.5 kW/(m3/s), the unit runs at a sufficiently low speed and the electricity consumption is low. The following mnemonic can be used to help select the correct unit: If the ventilation unit has an SFP of below 1.5 kW/(m3/s), it is quiet and has boosting reserve.

Ventilation should be run at the designed rate to ensure good and functional indoor air quality. Therefore, mechanical ventilation systems must be kept on at all times, espe-cially in modern, airtight buildings. Even when the building is unoccupied, impurities originating from construction materials are released into the indoor air. If a school build-ing’s ventilation system is shut down for the holidays, this will result in bigger problems. Airborne impurities accumulate on surface materials and are then released back into the indoor air when the ventilation system is switched back on.

Sufficient ventilation must never be compromised to gain energy savings.

Air leaks from structuresToday’s new, energy-efficient buildings are much more airtight than what we were previously used to. At the beginning of the century, a typical building envelope air leakage rate (q50) for new detached houses was about 4 1/h, but the current values are below 1.5 1/h, and the building envelope air leakage rate for a zero-energy building is about 0.4 1/h

An energy-efficient building is always airtight. Therefore it is easy to keep warm – or cool – as necessary. The indoor climate of an airtight building is easy to control because there are no uncontrolled air flows. However, this is not to say that an airtight building does not have a sufficient amount of air to breathe. The problem with houses that were built after the 1970s oil crisis and that were said to be as airtight as a bottle was not the airtightness of the structures but insufficient ventilation.

In an airtight building, mechanical ventilation is also required to ensure the flawless operation of structures. Ventilation must be able to maintain a slight negative pressure in the airtight building so that humidity that condenses in cold cannot enter into the wall structure under any circumstances. The most efficient way to ensure this is to direct all air through the ventilation system.

The ventilation of a leaky building cannot be controlled by any mechanical units, and the energy consumed to heat the air leaking uncontrollably out of the building cannot be recovered, even if the ventilation system is equipped with a heat recovery unit.


Example:

SFP 1.5 kW/(m3/s) in euros (a 120-m2 house, air flow rate 70 l/s, LTR-3 MDE ventilation unit)Input power valuesFans: (52 + 53) W = 105 W Heat recovery unit motor: 5 WAutomatic control: 9 WTotal: 119 W = 0.119 kW

Energy consumption per year0.119 W x 8,760 h = 1,042 kWh/year

Ventilation system electricity cost:1,042 kWh x €0.13/kWh = €136/year

Project:Handler:

Page 115.07.2015

LTR-3 MDE

Supply air

Extract air

Outdoor air

Exhaust air

Datasheet: LTR-3 MDE

Ducts

Ø 160 mm

Width

833 mm

Height

510 mm

Depth

480 mm

Weight

52 kg

Nominal fan power 119 W

Rotary Heat Exchanger

Electric heating power 500 W

No cooling

Cold installation possible (requires extra insulation)

Product number P02 212 0002

Electrical data:230 V/50 Hz, 1-phase, fuse 10 A quick

Sound levels: 63 125 250 500 1k 2k 4k 8k dB dB(A)

Room 59 51 53 44 37 32 29 24 60,4 47,0

Room: 10 m2 absorption LpA:

43,0

Supply air 87 79 71 46 63 61 55 49 88,0 69,6

Extract air 70 71 60 39 52 42 35 27 73,8 58,5

Outdoor air 68 71 60 54 52 42 35 27 73,3 59,0

Exhaust air 86 80 72 68 64 61 54 48 87,4 70,9

Design values: Supply Exhaust

Air flow: 70 l/s 70 l/s

External pressure: 115 Pa 115 Pa

Filter class: F5 F5

Results:Supply: Exhaust:

At calculation point:

Fan speed: 73 % 73 %



Fan power: 52 W 53 W

SFP:1,50 kW/(m3/s)

Maximum power:



Max boost: 33 % 32 %

Rotating heat exchanger:

At calculation point 0 °C / 90 %RH:

Efficiency:78,3 %

Supply air after exchanger: 16,4 °C

Heating need: 134 W

Coils:

Heating coil: 500 W Electric Ø125mm internal

Face velocity: 5,70 m/s

Annual calculations: Camborne, Great Britain

Heat recovered from extract air: 5649 kWh

Waste air minimum: 18 °C

Annual supply air heating: 75 kWh

Heat factor:

1 kWh electricity = 5,8 kWh

heat

The above-mentioned values apply to a single air handling unit - not air

handling systems

Ensto Enervent Oy

Kipinätie 106150 Porvoo, Finland

www.enervent.fi

p. +358(0)207 528 800

fax +358(0)207 528 844

3.1 Heat and cold recovery in ventilation systemsVentilation removes air from the building and as a result it inevitably causes heat loss. This kind of wastage cannot be accepted in energy-efficient construction. The more efficient heat recovery system the ventilation unit has, the more energy efficient the entire system is and the more the customer saves on his or her electricity bill.

The annual efficiency of new ventilation units can be up to 80%, and even over 90% if the system is equipped with an extract-air-source heat pump connected to heat recovery.

In a plate heat exchanger, heat is transferred from the extract air through the walls of a fixed cell to the cold air delivered into the building. The annual efficiency of plate heat exchangers is typically about 50...65%, and according to some manufacturers, the annu-al efficiency can be over 75% in the latest heat recovery units with cross-counter flow heat recovery cells. Human load and indoor air humidity have a significant effect on the annual efficiency of plate heat exchangers. If the humidity level of the indoor air is high, the plate heat exchanger requires frequent defrosting and the supply air is heated with electric coils, for example. This decreases the annual efficiency.


The rotating heat exchanger is a regenerative, heat-storing unit. This is a very efficient way of transferring heat, because the heat is shifted directly from the heat exchanger surface without passing through any matter. In a rotating heat exchanger, the warm extract air heats the cells for half a turn. This heat is then released into the outdoor air during the second half of the turn. A rotating heat exchanger has a notably higher mass and heat transfer surface area than a traditional heat exchanger. Due to the higher mass, it can store more heat. The annual efficiency of heat recovery can exceed 80%, and if the rotating heat exchanger is combined with an extract-air-source heat pump, annual efficiency values of over 90% can be achieved.

Ecodesign directiveThe objective of the European Union's Ecodesign Directive (2009/125/EC) is to reduce the en-vironmental impacts of products and improve energy efficiency in particular. The directive promotes sustainable development and the level of protection of the environment, and it increases the security of the energy supply. By virtue of the Ecodesign directive, the environmental requirements for product design are specified for different groups of products that consume electricity. In conjunction with this, an energy label which helps in selecting the correct product is introduced for products. This energy label is already used for domestic refriger-ation equipment and televisions, among others.

For the HVAC industry, ecode-sign requirements already exist for air conditioners and comfort fans, space heaters, combina-tion heaters, water heaters and storage tanks. The requirements for boilers, central heating and cooling systems and air condition-ing and ventilation systems are under preparation. The ecodesign requirements for air conditioning and ventilation systems will enter into force at the beginning of January 2016.

The ecodesign requirements will clarify the design and imple-mentation of energy-efficient ventilation systems and also make it easier to compare different solutions.


If necessary, the heat transfer of a rotating heat exchanger can be controlled steplessly by adjusting the motor speed or stopping the motor completely (complete or partial bypass of heat recovery). This means that cool, completely free outdoor air can be utilized in cooling. The possibility of utilizing cool outdoor air for cooling at night is es-pecially important in passive and zero-energy houses. It contributes to keeping cooling energy costs under control, thus making the entire building more energy efficient and environmentally friendly.

A rotating heat exchanger can also be utilized in cooling recovery when the outdoor air temperature is higher than the temperature of the extract air from the cooled space. Since this solution recovers cooling energy and moisture, it also improves the total energy efficiency in summer when the ventilation system is used for cooling. Therefore, this should always be taken into account when calculating the annual efficiency. For example, the German Passive House Institute takes the unit’s input power/m3 and mois-ture transfer Pel <0.45 Wh/m3 into account. The recovery of heat and cold can be further improved with heat pumps.

In a glycol heat exchanger, heat is recovered with a fluid-based coil located between the extract and supply air flows. At its best, the annual efficiency of glycol heat exchang-er systems is at the same level as traditional plate heat exchangers (about 50...60%). The fluid-based heat recovery system works best when the air volumes are high. This technology is available as an option to enable the Enervent Pallas ventilation unit to be used in sites where a rotating heat exchanger cannot be used.


CCeerrttiiffiiccaatteeCertified Passive House Component For cool, temperate climates, valid until 31 December 2014

www.passivehouse.com 0252vs03

Category: Heat recovery unit

Manufacturer: Ensto Enervent Oy

06150 PORVOO, FINLAND

Product name: Pelican eco ED(DP), Pelican eco EDE(DP),

Pelican eco EDW(DP), Pelican eco

EDX(DP)

This certificate was awarded based on the following

criteria:

Thermal comfort θsupply air ≥ 16.5 °C 1)

at θoutdoor air = -10 °C

Effective heat recovery rate

ηHR,eff ≥ 75%

Electric power consumption

Pel ≤ 0.45 Wh/m³

Moisture recovery Moisture recovery rate < 0.6 yes

Adjustment of air flow by means of

moisture control required: no

Air Tightness Interior and exterior air leakage rates

less than 3% of nominal air flow rate

Balancing and adjustability Air flow balancing possible: yes

Automated air flow balancing: yes2)

Sound insulation Sound level Lw ≤ 35 dB(A) not met

Here Lw = 47.2 dB(A)

Unit must be installed in a separate

building services room.

Indoor air quality Outdoor air filter F7

Extract air filter G4

Frost protection Frost protection for the heat

exchanger with continuous fresh air

supply down to

θoutdoor air = -15 °C

1) Only with additional heater coil in the supply air stream

2) Available as optional equipment

Further information can be found in the appendix of this certificate.

Passive House Institute Dr. Wolfgang Feist 64283 Darmstadt GERMANY

Certified for air flow rates of

214 – 306 m³/h

ηHR,eff

85%

Average moisture recovery ηX=0.47

Electric power consumption

0.44 Wh/m³

In its definition of passive house, the German Passive House Institute takes the unit’s input power/m3 and moisture transfer Pel <0.45 Wh/m3 into account.


Annual energy consumption with different ventilation solu-tions

HEAT RECOVERY METHOD ANNUAL ENERGY CONSUMPTION

Roof ventilator (no heat recovery) 16,600 kWh

Cross-flow plate heat exchanger 8,500 kWh

Counter flow plate heat exchanger 7,000 kWh

Rotating heat exchanger 4,700 kWh

A rotating heat exchanger will pay for itself quickly through the heating energy saved.

3.2 Heating and coolingEvery building needs some kind of heating system. For decades, there have been just a few viable main heating systems, but now builders have a myriad of options to select from.

Air heating, which was used in single-family houses from the 1960s until the beginning of the 1980s, has made a comeback as a respectable and useful heating system in con-nection with the increased focus on energy-efficient construction.

Because traditional massive heating systems are not necessary in highly energy-efficient buildings, a heating system integrated in the ventilation system is a functional and cost-effective option.

An additional benefit of air heating is that it does not require a separate heat distribu-tion system, which usually also requires quite a lot of space. Radiators can be problem-atic in terms of interior design, or impossible to install in front of large continuous glass surfaces. However, underfloor heating and/or a towel radiator is required in wet rooms for comfort and drying the space.

In the best and simplest form, the entire heating system – and, if necessary, the cool-ing system – is installed right next to the mechanical ventilation unit or even inside it.

Ventilation ducts distribute heat and cold through the system. An efficient heat recov-ery system takes the heat from the extract air and uses the energy to heat the outdoor air taken in. The heat recovery capacity can be increased by integrating an extract-air-source heat pump into the system. The system can also include a heat pump and outdoor unit to take heat energy from outdoor air. If desired, heat energy can be stored into an energy tank and then used for heating, for example, domestic hot water.

Any additional heat required can be covered with electricity. The system can also be part of a hybrid system, especially on sites where the demand for domestic hot water is high. In that case, a water-bearing fireplace, air/water heat pump or a low-power ground-source heat pump, among other things, can be connected to the energy tank.

Returning moisture back to room air in the wintertime

Rotating heat exchangers can transfer moisture from extract air into supply air in the wintertime, thus saving energy and heating costs. Moisture contains a large amount of energy, the utilization of which is often ignored. And air is never completely dry. The warmer the air is, the better it is at containing energy.

Under a normal heat recovery situation, a rotating heat exchang-er only transfers heat from the extract air to the supply air. If the outdoor air temperature is low, the temperature of the extract air decreases to dew point in the heat exchanger. The moisture present in extract air condenses on the heat exchanger surface and is transferred to the dry supply air when the exchanger rotates. This way, the rotating heat exchang-er helps to keep the indoor air humidity at a comfortable level in the wintertime by returning moisture back to the indoor air.

The indoor air humidity level must not rise excessively, even in the wintertime, and such a risk can be eliminated by proper dimension-ing of the ventilation unit. Ensto Enervent’s MD models come with the humidity boost feature as standard, and it is available as an option for EC models. This feature can take care of high moisture loads experienced temporarily due to laundry drying or having a sauna, for example.

In an energy-efficient building, the internal heat load can become so high that even if solar protection is in order, indoor air cooling is required during warm seasons to ensure comfort. The best way to tackle this problem is to do it with ventilation, in which case indoor air dehumidification can also be included in the system.

3.3 Humidity control“The building shall be designed and constructed in such a way that the humidity of indoor air will remain within the values specified for the intended use of the building. The humidity of indoor air must not continuously remain harmfully high, nor may humidity condensate in structures or on their surfaces or in the ventilation system in such a way that it will cause moisture damage, growth of microbes or micro-organisms, or any other health hazard.” Section D2, 2.3.2

“If the indoor air humidity exceeds the value of 7 g H2O/kg of dry air, the room air may be humidified for strictly demanding reasons only, such as when required by a production process or storage conditions. The value of 7 g H2O/kg of dry air corresponds to a room air condition where the relative humidity is 45% at a room temperature of +21 °C and where there is air pressure of 101.3 kPa. In order to minimize any harmful effects caused by low relative humidity of the indoor air, unnecessarily high room temperatures are avoided during the heating season.” 2.3.2.1

Good indoor air has a suitable humidity level for people, pets, interior materials and house structures. Indoor air that is too dry feels uncomfortable for everyone, not just those who suffer from respiratory organ diseases or atopy. It can even make you sick. Dry air slows down the movement of the cilia and impairs the removal of mucus from the respiratory tract. It impairs the ability of mucous membranes to resist inflammation. Low humidity levels also increase the generation of static electricity. Indoor air that is too dry can cause sparks to jump from a cat’s fur.

All-wood interior materials, such as parquet, wall paneling and furniture, do not respond well to an environment that is too dry.

Indoor air that is too humid is stuffy and thick to breathe. It is especially troublesome for those suffering from respiratory organ diseases.

On the other hand, dust mites thrive in humid conditions. Moisture condensing on surfaces and in structures also increases the risk of microbial growth.

Increased humidity levels experienced temporarily after having a sauna or doing laun-dry do not usually cause any harm. Windows may fog up because cold and smooth sur-faces are most prone to condensing moisture. Therefore, a curtain of water droplets may form on the cold inside surface of energy-efficient windows. A good ventilation unit has an automated humidity boost feature that takes care of temporary moisture loads.



This feature is standard in Ensto Enervent’s MD control system. If the relative humidity of extract air exceeds the set level, the unit automatically boosts the air flow rate to obtain the desired humidity level in the winter.

The relative humidity of indoor air should be between 20 and 60%. Getting into that range is not always easy in the varying Finnish conditions. Therefore, the ventilation system must be designed by competent designers.

During the heating season, indoor air is drier, RH about 25...45%, but on hot and humid summer days the relative humidity of indoor air can sometimes exceed 60%.

The need for cooling indoor air due to external heat load can vary a lot by year in Fin-land. In 2013, there were 26 hot days (temperature exceeding 25 °C), whereas in 2014, the all-time record was almost reached, with 38 days.

The need for dehumidifying indoor air due to air humidity level varies both by year and by season. Normally, the need for dehumidification is highest between late summer and early winter, especially in the south coast region of Finland. It is expected that cli-mate change will make heavy rains more likely, which will increase the need for further dehumidification.

About 33% less cooling power is required at +25 °C/50% (a) compared with +21 °C/40% (b)

1. Outdoor air; 2. After dehumidification (cooling coil); 3. After after-heating; 4. Indoor air

Mollier diagram for humid air

0,000 0,005 0,010 0,015 0,020 0,025

Vesisisältö, x, (kg/kg)

Entalpia, i, (kJ/kg)

-20

-10

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20

30

40

50

60

70

0,1 0,2 0,3 0,40,5

0,6

0,7

0,80,91,0

8090

100110

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140

Kuiv

an lä

mpö

mitt

arin

läm

pötil

a, T

, (°C

)

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30

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10

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0

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-15

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Water content, x, (kg/kg)

Enthalpy, i, (kJ/kg)

Tem

pera

ture

mea

sure

d w

ith d

ry th

erm

omet

er, T

, (°C

)


The effects of climate change on the energy consumption of buildings were simulated in the FRAME project in 2011. According to the simulations that used the data provided by the Finnish Meteorological Institute, the need for cooling buildings will increase by 10 to 30% by 2050, and by up to 20 to 75% by 2100.

If indoor air humidity levels vary significantly, it will have an effect not only on human comfort but also on the durability of wood materials in interior applications. Being a natural material, wood shrinks and swells with humidity. Parquet manufacturers rec-ommend that to avoid cracks or excessive swelling, the relative humidity of indoor air should be kept at 40...60% and room temperature should stay between +18...24 °C.

In air conditioned spaces, conditions including indoor air humidity can be maintained at an optimal level, regardless of external conditions and use.

The dehumidification of indoor air can be implemented in the ventilation system by uti-lizing ground-source heating or an air/water heat pump system, or the ventilation unit’s heat pump. It cools the supply air down – the minimum temperature is +7 °C – causing the air to dry. Then the supply air is heated to a comfortable temperature. The ventila-tion unit’s dehumidification function is used when there is no temperature-related need for dehumidification but the air is too humid. The system supplies comfortable, dry air which is at the correct temperature.

3.4 Indoor air superheroVentilation design requires specialized skills and competence. Mastering the basics and being familiar with the regulations is not enough. Each building is different and the needs and wishes of its residents are unique. Therefore, no single solution can be copied identically at another site. The HVAC designer must be an experienced professional in his or her field.

A good HVAC designer starts from the needs of the building’s end users – workers or residents – and can identify the issues and information required for specifying the in-door air quality level, even when the residents or other end users cannot provide them directly. The HVAC designer must be a good interviewer and judge of character.

When designing the ventilation system for a commercial building, a good HVAC designer is familiar with the future use of the building, to the extent that he or she can take account of and predict the challenges posed by the use to ventilation, even under changing conditions. The designer must also be aware of any special challenges when designing cleanrooms or spaces with precisely-controlled air conditioning systems for museums, art galleries, pharmaceutical and food factories and laboratories, for example. The HVAC designer must be something of a specialist of all fields.

A good HVAC designer is also sufficiently familiar with structural physics, the moisture behavior of different structures and construction materials, and other properties that have an effect on indoor air quality. The HVAC designer should also have a slight inclina-tion towards being a structural designer and construction manager.


A good HVAC designer is a real indoor air superhero!

A good HVAC designer is familiar with the requirements of energy efficiency but can also understand human behavior. The completed system must also operate well when the end user does not quite understand the operation of the system and had no desire to learn it. The HVAC designer must be an energy specialist and behavioral scientist.

When designing the ventilation system for a residential building, a good HVAC designer is first and foremost a resident as well. The designer takes changing life situations, extended families, suddenly increasing moisture loads due to sports activities (or teen-agers), pets, aquariums and excessive amounts of houseplants into account. The HVAC designer must be a specialist on how people live their lives.

People get used to a lot of things. If someone has lived in a home with poor indoor air quality, they may not be aware that something better is available. Then it is the HVAC designer’s duty to let him know what each and every resident and worker is entitled to: good indoor air. A good HVAC designer is a real indoor air superhero!

NEEDS ASSESSMENT HELPS IN DETERMINING THE DESIGN LEVEL

4.1 Interacting decisions when selecting a ventilation system for a single-family house

Anyone who is planning to build a detached house or renovate an old home faces a huge number of difficult decisions. Most of the decisions made at a relatively early stage of planning have far-reaching consequences that a novice builder may not be able to anticipate.

Individual decisions that seem reasonable at first can later rule out options that would have been utilized. For example, selecting a prefabricated house kit which has a nice floor plan and façade may also set the available building services engineering solutions for good. Some of the desired changes may prove impossible to implement or may increase the price of the kit excessively. Each building, along with its building services engineering solutions, must be designed as an entity.

From the very beginning of the project, the most trusted people for a homebuilder or renovator are the main designer specialized in single-family houses, and the HVAC designer who can go through the choices with the customer and point out what each decision can lead to and what it might rule out at a later stage.

The main designer should familiarize him or herself carefully with the customer fami-ly’s lifestyle, hobbies and wishes. The pros and cons of their current home are discussed. Any issues that should be avoided or are unacceptable in the new home are also considered at this stage.

The list of wishes and needs are then compared with the available resources. The aim is to fulfill all of them in a cost-effective manner, taking the different options into account and comparing their cost impacts – both at the purchasing stage and when the resi-dent is in situ. Ultimately, the budget has the final say on what is possible and what can be left out.

It is critical to have the HVAC designer participate in the planning process at an early stage as possible in both new construction and renovation projects. This way, it can be ensured that implementing the desired solutions will not be impossible or difficult due to choices made at an earlier stage.

A ventilation system requires a lot of space. Therefore, the system components and duct routing should already be set before interior and furnishing design takes place.

The better the architectural and building services engineering solutions are matched at an early stage of planning, the better the house works.



4.2 Finding out the site details and the customer’s needs

The first steps in designing the indoor climate and ventilation system for a new project are the assessment of the customer’s needs and wishes and recording the basic infor-mation of the project. The needs assessment makes the designer’s work a lot easier. It provides explicit starting points for design and also speeds up the actual design work and review of different system options in particular.

It is easier to start from scratch than to modify a pre-set model – which may have been in use for a long time – to meet the customer’s needs.

When compared with designing the ventilation system for a shopping center or apart-ment building, designing the ventilation system for a detached house is somewhat easi-er by nature, because at least the end users in the near future can be interviewed easily. A newborn baby or a dog may not be able to express their views about the matter but in any case they can be taken into account.

In the needs assessment, an experienced designer can also identify issues relating to the customer’s life and needs that the customer themselves may have considered irrelevant.

Based on the wishes and needs of the end users/residents, a functional diagram can be prepared for the building. The diagram shows at a glance what functions each space serves and what building services engineering solutions they require – and not only for ventilation. The system plan can be called “Functional house”.

4.2.1 Key factors related to the plot and building

» The plot and construction location with cardinal directions and terrain informa-tion. Information on whether the plot is in the countryside or in an urban setting, the location of any busy traffic routes and water bodies nearby, and relevant infor-mation about trees and topography.

» The position of the building in the plot/cardinal directions. The sun’s path, geographical obstacles, wind conditions.

» The size of the building as well as its shape, residential floors, area/floor, volume.

» Building type/architecture: the size of windows and the directions they face, the overhang of the eaves, passive solar protection, floors, spaciousness of indoor spaces.

» The number of wet rooms

» The targeted energy class: air permeability of the building, thermal resistance, energy rating of windows.

» Heating/cooling energy demand


» Other factors affecting indoor air quality, such as the need for humidity control, cooling.

» Heat distribution system

» Main heating source, additional heating sources

» Acoustic conditions

4.2.2 Residents’ needs: optimal conditions for sports enthusiasts and cat lovers

» Number of residents A good designer does not just record that there will be two adults and two children. The number of pillows in the architectural drawings is not the absolute truth. The plans must also prepare for changes in family conditions. New children can be born and older ones may move away. In extended families, the number of children can vary even on a daily basis. The family may hire an au pair or have grandma come to stay in the guest room.

» Pets A small dog or a couple of cats will not have an impact on the ventilation design, but the situation is different if the residents start to breed Bernese mountain dogs who spend all day indoors, or the pair of cats results in a clowder. An efficient central vacuum cleaning system might be a good idea, and the laundry room should be equipped with a wash station for those muddy paws. The constant washing of paws increases the moisture load several times a day during muddy periods.

» Physical activities Gym workouts and other indoor exercises have an effect on the required ventila-tion capacity. Drying sports clothes require space and they also have an impact on ventilation.

» Dehumidification need Frequent saunas, teenagers’ long shower sessions and the use of a whirlpool bath increase the moisture load, as do aquariums, terrariums and an excessive amount of houseplants.

» High internal heat load The internal heat load is increased by consumer electronics, terrariums, grow lights and large pets.

» Changes in the use of the building A building’s purpose of use may change temporarily: a single-family house may take on day care activities for children or the elderly, or a small-scale catering business can be started.

» Hobbies that impair indoor air quality Not all hobbies are equal in terms of their impact on indoor air quality. In addition to breeding animals or growing plants, activities that should be taken into account include woodworking, painting, and tinkering with cars or motorcycles.


4.2.3 Discovering hidden wishes

The majority of people share similar wishes for indoor air quality. It should be constant, ideally warm, fresh, unnoticeable, quiet and easily adjusted.

Discussing the obvious issues is usually easy. On the other hand, indoor air cooling and similar features may be something that people do not know to bring up. Indoor air cooling must be discussed in connection with the needs assessment in any case.

People’s ability to withstand unpleasant conditions and hot indoor air varies a lot. Those who feel especially uncomfortable if the indoor air is too hot include the elderly, babies, pregnant women and those suffering from heart or respiratory organ diseases.

Nobody benefits if one or more air-source heat pumps have to be fitted in a new house after the first summer to tackle unpredictable cooling needs.

4.2.4. Conveniently controlled or fully automatedThose who are used to natural ventilation may think that ventilation control means the same thing as opening a window if the air is stuffy.It is advisable to allow plenty of time for discussing the control options and methods of the system during the needs assessment.

Because people experience indoor air differently, room-specific control is an important feature for many people in providing increased comfort.

Some people are more technically inclined than others. They like to monitor and record the realized consumption values and to adjust the system. Others value systems that adjust automatically as needed, without any human intervention. A single family can in-clude both technologically-oriented geeks and other members who are more carefree. In any case, most of us think that a control system must first and foremost be so clear and easy to use that anyone can use it in everyday situations without a manual.

A system that people cannot use is totally useless.

That is why ease of use was the starting point for developing Ensto Enervent’s new intelligent eAir touchscreen controller. eAir’s logic is based on operating modes which can be controlled with a visually clear and simple touchscreen. The operating modes cover all ventilation needs and are activated simply by pressing the desired symbol on the screen.


Step 2: My wishes

Fresh air

Heat

recovery

ControlHeating with

air heat pump

Cooling with

air heat pump

Domestic

hot water

I am interested in the following solutions:

Better ventilation

Heating via ventilation

Cooling via ventilation

Reduce radon concentration

Smaller energy consumption

Replacing old ventilation unit with new

Domestic hot water

Complete solution, incl. ventilation and heating

My contact information:

Name

Street address

Zip code and town

Phone number

E-mail address

2

Step 1: My house today

Heating source:Additional heating:

Electrical heating

FireplaceExtract air heat pump

Water mantled fire placeGround-source heat pump

Air-air heat pump Air bourne heating

OtherDistrict heating

Ventilation:Natural ventilation

Supply and extract air ventilation with heat recoveryExtract fan

No ventilationExtract via heat pump

OtherOther information:For installer:

Living area m²

x 0,5 l/s =Number of residents

x 4 l/s =Where do you live?

Dimension temoerature =Year of constructionAnnual energy consumption kWhOther

1

4.2.5 An example of a needs assessment for designing a ventilation system for a single-family house

Here is an example of a proper needs assessment. A suitable ventilation unit model is found when the resident and designer go through the assess-ment together. Moreover, the assessment makes it easy to select the correct ventilation solution that is suitable for the main heating source, for example.


4.3 Sustainable solutions A significant proportion of the professional customers of HVAC designers emphasize sustainable solutions in their choices, but these issues are becoming more and more important for homebuilders and renovators as well. The actual topic under discussion may not be sustainable development or even environmental friendliness, but at least saving energy and the long service life of the selected solutions are equally important issues for all types of customers.

A long-lasting solution is one of high-quality and made of high-quality materials, it is easy to maintain, repair and replace, and it is also modifiable/scalable if necessary. This way, the solution and the entire building can operate in an energy-efficient way for the entire life of the building.

An energy-efficient solution means that the requirements set for ventilation are met by using the minimum amount of energy possible. Properly designed and used ventilation that utilizes the latest equipment and solutions is very energy efficient and consumes only a small amount of heating energy and electricity. Moreover, a properly designed ventilation consumes only a small amount of electricity. For more information on the Specific Fan Power (SFP), see page 14.

We must also remember that the ventilation system can have features that both in-crease the comfort of living and contribute to saving energy. For example, the supply-air cooling feature makes portable air conditioners and air-source heat pumps redundant. Thanks to the room-specific control, those who feel the cold do not need additional heaters. Storing recovered heat into an energy tank also provides heat for domestic hot water.

Simplicity and versatility of the building services engineering solutions are key contrib-utors to sustainable development. Technological development accompanied by the improved energy efficiency of construction have enabled the introduction of modern air heating systems. These versatile and energy-efficient systems are associated with mechanical ventilation and utilize the EnergyBUS. They can be used in all types of build-ings, from detached houses to stores and industrial buildings.

4.4 Modifiability and adaptability to changing conditions

In commercial projects, it is expected and obvious that the end users come and go and the premises must be as modifiable as possible in order to maintain their usability. The ventilation design should also be able to accommodate foreseeable changing needs – at least to the extent that the selected solution does not become prematurely outdated or is too rigid to be modified.


When possible, similar flexibility should also be taken into account when designing the ventilation system for a detached house.

The energy efficiency requirements for new buildings will become tighter in the near future. Even though most new detached houses cannot reach the nearly zero-energy target of 2020, the E-value and the indoor air quality level will largely determine the market value of old houses in the future. High-quality indoor air appeals to buyers.

Even though most families who build their own home do so with the idea that it will be theirs for life, it is likely that the house will be sold at some point in the future. At a minimum, the building services engineering solutions should be such that they do not prevent the sale but rather be valuable selling points. In this respect, it is a definite asset if the ventilation system is flexible, versatile, energy-efficient, long-lasting and easy to modify and upgrade.

It is assumed that in Finland, climate change will result in more frequent warmer sum-mers with increased rainfall, and snowy or rainy winters. The ventilation system must also be able to cope with these conditions.

4.5 The challenges of commercial projectsThe progress of design processes is quite similar, whether the building is a single-family detached house, an apartment building, a serviced office or shopping center. Naturally, the scale is completely different and the number of variables is usually multiplied. The main objective in each project is to provide the customer/end user with the best possi-ble indoor conditions in the most energy-efficient and cost-effective manner possible.

If the end user is already known at the beginning of the project, the needs assessment is easy to do. The situation is more problematic if the end user is not yet known or the number of end users is high. In such cases, a professional developer who aims for a good quality indoor climate is a valuable partner for the HVAC designer.

In modern serviced office projects, only the main tenants are usually known at the initial stage of the project. The project proceeds on the basis of their needs and wishes but in a way that enables different options for future parties whenever possible. Changes in indoor conditions in particular can be impossible or very expensive to implement dur-ing the construction stage. Therefore, rental premises and the conditions therein should be designed to the highest quality possible, but they should also be as modifiable as possible.

Special projects, such as exhibition premises and museums, health care facilities, research centers or laboratories and pharmaceutical factories that require cleanrooms, are built to provide specific, predetermined indoor conditions. The designers’ task is to fulfill these requirements within the budget and in such a way that the building entity


operates as designed in an energy-efficient and environmentally friendly way for its long service life.

This task can be facilitated by environmental classification systems, for example, which provide good guidelines for implementing a high-quality building and indoor condi-tions that are both energy-efficient and environmentally friendly, on top of fulfilling needs.

4.5.1 Green constructionGreen Building Council Finland defines green construction as a way to construct and use methods that are ecologically responsible and efficient in terms of the use of resources for the entire life of the building. Green sustainable construction improves the quality of construction in all public, commercial and residential buildings.

At the moment, construction accounts for 30% of global carbon dioxide emissions and for 40% of the global consumption of natural resources. The main objective of green construction is to optimize the environmental impacts of buildings by utilizing life cycle thinking, in which the materials and products used in a building are assessed by using the best possible level of construction as the starting point.

The design of green buildings is based on three general principles: » Energy efficiency – the buildings consume as little energy as possible.

» Conservation of natural resources – natural resources are limited.

» Indoor environmental quality – green buildings are designed to be healthy.

Green Building Council Finland strives to make sustainable development a natural part of the real estate and construction industry. The association provides its members with training in sustainability, information services and development.The members include professional real estate owners, developers, residents/occupants, providers of facilities and user services, planners, designers, contractors, and commercial and industrial enterprises. The association has 29 founding member organizations.

In addition to promoting green construction and communication, one of Green Build-ing Council Finland’s key tasks is to promote the use of environmental certifications for buildings.

4.5.2 Environmental classification systems help in designEnvironmental classification systems are developed to make the comparison of different buildings easier. This information is used by investors, authorities and users alike. A building with a high rating is more valuable as an investment and attracts higher rent levels than a neighboring lower-rated or uncertified building.

There is no single superior environmental classification system. At the moment, one


Finnish system – PromisE – and two international systems are used in Finland. The American LEED and European BREEAM systems are rather similar and focus on similar issues. The number of certified buildings around the world is already in the hundreds of thousands.

The EU finances a number of environmental classification projects. These include, for example, Green Public Procurement, Open House and Super Buildings. Green Public Procurement focuses on public premises and public procurement projects.

As Finland is a country of extensive environmental classification systems, we also have other tools in which some aspects of building’s environmental impacts are assessed, such as the Energy certificate for buildings, indoor air classification and condition certifi-cates for housing companies.

LEED

In the LEED (Leadership in Energy and Environmental Design) certification system, a con-struction project is assessed by using the following six criteria: sustainable sites, water efficiency, energy and atmosphere, materials and resources, indoor environmental quality and innovation in design. The highest level of certification, platinum, requires 80 points or above, gold 60, silver 50, and a minimum of 40 points is required to qualify for the ‘certified’ level.

BREEAM

BREEAM (Building Research Establishment’s Environmental Assessment Method) controls the building design, construction and operation. It assesses the environmental impacts related to management, energy and water use, materials, land use and transport, for example. Each section is scored and the building is rated based on the scoring. Existing buildings can also be rated. BREEAM Europe covers office, retail and industrial buildings, but it can also be tailored to other building types.

PromisE

The Finnish PromisE system is an example of a national classification system. Local conditions and needs are taken into account in the development of this practical and easy-to-understand classification system. The basic idea of the system is to assess the key environmental impacts of the building by using simple and reliable indicators. The results are scored and the building is rated on a scale of A to E, indicating the envi-ronmental performance of the building. An environmental classification system may initially be time-consuming, but it will become a good tool for designing high-quality indoor climate. In more demanding projects, design work is carried out by a team, along with the help of a consultant who is familiar with requirements of the environmental classification system.

Environmental classification systems require that all elements of construction are as-sessed during the design stage. Achieving the desired class or rating may require careful research into various combinations of structural and building services engineering solutions, and the selected classification system and its requirements must be known. The designers and suppliers of ventilation cooling systems should know what require-ments the selected classification system sets for the ventilation cooling systems and its components. The requirements of the selected classification system can be fulfilled with a number of different solutions. In this respect, the designer is given the freedom to be creative.


4.6 Enervent solutions for ventilation needsAdmittedly, it is difficult to present various ventilation solutions to customers using the names of units that are often accompanied with somewhat cryptic combinations of letters and numbers. Enervent ventilation solutions are classified into easily understand-able groups based on their features. Selecting the correct system is easy after needs and wishes have been assessed.

The factors that must be taken into account include the indoor air carbon dioxide content, humidity control, noise level, filtration level of the supply air, system control properties, need for cooling/air conditioning, production of domestic hot water, and so on. There are five design levels, from Standard up to the comfort provided by the Superior level.

Even the basic mechanical ventilation level includes the following properties and systems: a ventilation system that ensures a sufficient supply of fresh air, a heat recovery system that increases the energy efficiency of both the system and the entire building, and a control system. The higher the selected design level is, the more accurate control of the indoor climate the ventilation system enables.

4.6.1 StandardThe Standard level solution ensures fresh air and heat recovery and control systems. Enervent options: MD and eco EC.

4.6.2 ClassicThe Classic level also includes supply-air heating. Supply-air heating is a very important feature in the northern climate because it adds a tremendous amount of comfort by

Standard

Fresh air Heat recovery

Control system

Units:• MD• eco EC

Classic

Fresh air Heat recovery Supply-air heating

Control system

Units:• MDE• MDW• eco ECE

Dynamic

Fresh air Heat recovery Supply-air cooling

Supply-air heating

Control system

Units:• MDE-CG• MDW-CG

Premium


Cooling with an air-source heat pump

Heating with an air-source heat pump

Control system

Units:• HP eAir• MDX

Superior




Control system

Warm-water supply

Units:• HP Aqua

Dehumidifi-cation

EnergyBUS


eliminating cold drafts. There is no need to fear energy loss, because this function is switched on only when needed. Enervent options: MDE, MDW and eco ECE.

4.6.3 DynamicThe ventilation system at the Dynamic level includes supply-air cooling with ground cir-cuit fluid. This increases comfort levels significantly during summer, but cooling is often needed in the early spring when things begin to warm up. In airtight passive houses on sunny and open plots, and if the indoor heat load is high, there can be a need for supply-air cooling as early in the year as March. Enervent options: MDE-CG and MDW-CG.

4.6.4 PremiumWhen an air-source heat pump is included in the ventilation system, the system enables both heating and cooling of the indoor air with the heat pump. In HP eAir models, the extract-air-source heat pump is integrated into the ventilation unit. The MDX mod-els have a separate outdoor unit. The heated/cooled supply air is evenly distributed throughout the building through the ventilation ducts. Enervent options: HP eAir and MDX.

4.6.5 SuperiorThe Superior level solutions include all the properties of the Premium level, as well as enabling the storage of heat into an energy tank to be used for heating the supply air, heating domestic hot water, and for a water-based heating system. Enervent option: HP Aqua.

4.7 EnergyBUSIn an energy-efficient building, energy that has already been gained is recovered and reused as efficiently as possible, whether this energy was purchased or free. Free energy includes, for example, thermal radiation from the sun and the heat energy generated by the use of the building by people, pets and equipment. This free energy contributes to the heat load, and this energy was exhausted to outdoors as waste heat in the past.

For the time being, the energy lost down the drain with greywater is still waste energy, but by utilizing the EnergyBUS all other heating and cooling energy can be recovered and reused in the most efficient and economical way in terms of the building and its use.


The heat load and heating need in a building is not necessarily distributed evenly. For example, heating need is high during the night in winter, and excess heat is generated in office buildings during the afternoon in particular when all workers are at work and all computers and other equipment are switched on. One side of a building may require more heat and the other may have excess heat. Energy is purchased for one side and wasted on the other.

Let us consider, for example, a normal detached house. A heated sauna may have excess heat, but the bedroom at the rearmost corner of the house requires heating. An industrial building may have machines generating so much heat that they require cooling, while the workers in the office rooms feel cold.

Ensto Enervent’s EnergyBus enables the excess energy to be transferred to where it is needed. The internal heat load of the building is utilized first, and energy is purchased from outside only when it is really needed.

The EnergyBUS transfers the recovered energy at the right time to where it is needed. The recovered heat (and cold) energy is stored in an energy bank (energy tank) from where it can be used to heat or cool the building via ventilation when needed. The energy can also be used for a water-based heating system or for heating domestic hot water. The recovered energy is automatically transferred to where it is needed or stored in the energy tank for later use.

4.8 Complete ventilation solution with the EnergyBUS

By utilizing the EnergyBUS, control of the building’s heat loads and energy consumption can be performed with one system. For example, the Enervent Pallas HP Aqua cir-culation air unit is designed to take complete care and control of the building’s indoor climate, heat recovery, production of domestic hot water, and water cooling. It fulfills the dream of many designers and builders to have a comprehensive solution that is both simple and reliable.

EnergyBUS can be installed and implemented in any building size. Example cases of an industrial building (new building), grocery store (renovation) and a new detached house can be found in Chapter 13. A flexible system can be tailored to need. In a detached house, the need for heating and cooling depends on the energy efficiency of the building, but the demand for hot water is higher than in, say, a grocery store.

The need for indoor air dehumidification and cooling will also continue to increase in residential buildings. In grocery stores, energy efficiency requirements state that doors must be retrofitted to existing refrigeration equipment, which in turn results in excessively high relative humidity of indoor air, especially in summer. Open refrigeration equipment have contributed to the dehumidification of indoor air, but if the equipment


is fitted with doors, dehumidification must be performed entirely by the ventilation system.

Moisture is also generated in many production facilities in normal operations.

The need for cooling in energy-efficient buildings can be reduced by architectural and structural (passive) means, but also by ensuring the correct moisture balance of indoor air. The higher the relative humidity is, the more hot and uncomfortable it feels. By maintaining the indoor air humidity at the optimum level, the indoor temperature can be kept a few degrees higher without it feeling uncomfortable. Proper air humidity con-trol is also good for interior materials, furniture and the operation of house structures.

4.8.1 Example: apartment building

A good example of utilizing the EnergyBUS in ventilation, heating and cooling is an apartment building with a grocery store at street level.

Normally, the ventilation and refrigeration systems for the store are designed and imple-mented as a separate entity, and the systems required by the apartments above form another entity. The building may be connected to a district heating network, and the heating costs are divided between the residents in proportion to floor area.

If the systems for the same building are designed and implemented to be as energy efficient and environmentally friendly as possible, ideal indoor environmental quality can be created for all spaces in the most energy-efficient and economical way and with the lowest emissions possible.

The need for heating, cooling and indoor air dehumidification vary between different spaces, even during the same season. The sunny side may require cooling in early spring, while the heating season is still far from ending on the shady side of the build-ing. The need for cooling and dehumidification is increased heavily in the store towards the summer. When the recovered heating and cooling energy is stored in the energy tanks, it can be utilized in a flexible manner for different energy needs in different sec-tions of the same building: for cooling, heating or domestic hot water. See page 120.

4.8.2 Ensto Enervent Pallas HP Aqua circulation air unitEnsto Enervent Pallas HP Aqua circulation air unit is the most advanced and versatile solution by Ensto Enervent for a building’s ventilation, heat recovery, control, heating, cooling and dehumidification needs, and for the provision of hot and cold water. It is a ventilation unit equipped with an integrated extract-air-source heat pump (air flow 720...2520 m³/h, 300 Pa). It is an all-in-one unit: no separate indoor or outdoor units are needed, and no separate refrigeration installation is required on-site. The entire system is controlled by the Enervent MD control system.

Especially when the building is cooled down in the hot summer days, energy is usually


wasted due to the heat pump process, but the Enervent Pallas HP Aqua circulation air unit utilizes this energy for heating domestic hot water and/or indoor air cooling because it can provide its energy tanks with both hot and cold water. The stored energy can be used for heating and cooling the spaces as necessary either via a water-based distribution system or with circulation air, for example.

The air recirculation function circulates the indoor air through the heating coil in case heating is required but ventilation is not necessary.

The operation of the unit equipped with the recirculation function is switched from a circulation air unit into a normal ventilation unit by a CO

2 sensor if the sensor’s set value

is exceeded; that is, if people enter the building. The indoor air humidity is controlled by using the value of the absolute moisture content of the supply air (g/kg). After-heating – to avoid cold draft – is conducted by utilizing the heat provided by the unit itself to the energy tank.

The excellent annual efficiency of the unit is based on the combination of efficient heat recovery and heat pump. The annual efficiency of the units of this product family can exceed 90% if equipped with a rotating heat exchanger, or it can be at about 45...65% if the heat recovery is conducted by a fluid-based glycol heat exchanger.

The Enervent Pallas HP Aqua circulation air unit can be used as a supporting heating system, and, in some cases, as the main heating source, especially in low-energy and passive houses. It is an especially excellent solution in areas where heat pump outdoor units are not allowed on façades.

The Enervent Pallas HP Aqua circulation air unit complies with the requirements of the RES directive.

In the apartment building example above, the system included two energy tanks and an Enervent Pallas HP Aqua circulation air unit on each floor.

When designing a system with an Enervent Pallas HP Aqua circulation air unit, modeling is necessary in order to be able to utilize its versatile possibilities in full and in the best possible way. The traditional “manual” modeling of buildings and cooling is no longer reasonable. Dynamic calculation that examines and models the operation of the build-ing moment by moment is required in order to have total control. Modeling can be used to examine how cooling, EnergyBUS, energy bank and the energy balance of the building behave in different external and internal conditions, for example. The modeling process for including the Enervent Pallas HP Aqua circulation air unit system in the popular IDA-ICE modeling software is under way.

The secret for designing a high indoor air quality in a simple, functional and energy-efficient way: Check first what can be done with just the ventilation system and use other means only after that!

Ventilation unit temperatures Energy report for zone “Ventilation unit”

Month Q_HEAT Q_COOL Q_REHEAT Q_RECOOL Q_HUM Q_FANS1 1017.0 0.0 2018.0 0.0 0.0 123.8.2 919.6 0.0 1881.0 0.0 0.0 111.73 719.4 0.0 1810.0 0.0. 0.0 124.24 174.3 0.7 1285.0 0.0 0.0 121.05 30.3 80.5 773.7 0.1 0.0 126.06 0.0 172.6 383.4 0.6 0.0 122.67 0.0 376.0 208.8 7.6 0.0 127.08 0.0 286.9 313.6 .3.0 0.0 126.89 12.4 36.5 721.9 0.1 0.0 122.0

10 301.4 0.6 1288.0 0.0 0.0 125.111 815.4 0.0 1697.0 0.0 0.0 120.312 935.7 0.0 1887.0 0.0 0.0 124.0

Total 4925.5 953.8 14267.4 11.5 0.0 1474.5

kWh (sensible and latent)

THE ELEMENTS OF A GOOD VENTILATION SYSTEM


5.1 Air flow dimensioningNormally, an HVAC designer designs the building’s ventilation system by applying the room-specific air flow guideline values specified in Section D2 of the National Building Code of Finland. Often the design ventilation rate is determined by the outdoor air flow rates, but in small houses, the room-specific extract air flow rates can be decisive. The design air flow rates are indicated in the ventilation drawings.

When the ventilation air flow rates for a single-family house are designed in accordance with the indicative non-boosted air flows of the occupancy period specified in Section D2, the resulting air flow rate is about 0.5 l/s/m2 on average. The average air flow rate varies slightly according to the size and type of the building. However, this air flow rate corresponds only to a satisfactory indoor air quality level in normal use. The basic level specified in Section D2 meets only about 60% of the requirements set for good indoor air. Section D2’s requirements are outdated with respect to new ener-gy-efficient buildings.

The old rules are no longer validDuring the last decade, the importance of ventilation has been recognized by those involved in commercial construction and industrial processes, for example. This progress has not quite reached the residential building sector. This may be explained by recent history: the breakthrough of mechanical supply and extract air ventilation was experi-enced only in the 2000s, and for detached houses in the 1990s.

The first comprehensive Finnish manual for HVAC design and dimensioning air flow rates was published as early as in 1959. In the manual, titled “Lämpö- ja vesijohto sekä tuuletustekniikan käsikirja”, the European ‘m3/h’ was used as the air flow rate unit – ‘l/s’ was only adopted later. A fascinating detail is that the air flow rates recommended in the manual for residential buildings were higher than the corresponding values of Section D2, published in 2003. For example, the bathroom air flow rate was 12% higher than the current minimum level.

A century or even 50 years ago, the use of water in buildings was completely different from the current situation. In pre-WWII Helsinki, it was common to ask others whether they already had a public water supply installed in their building. Wasteful use of water was not a common problem in houses without plumbing facilities, but the situation is different now. In the past, saunas were located in outbuildings. Today, people can have a home spa with a steam room and whirlpool tub in their own home.

These home spas are great for bringing some luxury to everyday life, but they should be taken into account in ventilation design. Unfortunately it is common that even the im-pact of a second shower head is not included in the design. At worst, the minimum air flow rate specified in Section D2 – 15 l/s – is used. Our recommended rule of thumb for bathrooms is 15 l/s per shower head, and if the room has a bathtub fitted, the minimum air flow rate is 30 l/s.


Only a few years ago, when mechanical extract air ventilation was the prevailing ven-tilation method, the design work was started by determining the extract air flow rates. This habit continued, and the same formula was used for designing supply and extract air ventilation systems. Therefore, the supply air flow rate was 90% of the extract air flow rate (0.9 x extract). It is definitely a better way to start the design work to assess the needs and determine the desired quality level and the supply air flow rates required for reaching the desired level. It must also be noted that in an extremely airtight house, the ratio between the supply and extract air flow rates cannot be 0.9. The underpressure prevailing in the house would be too high. The rule used in today’s building industry is that the supply air flow is 95...97% of the extract air flow.

Better if doubledAccording to Section D2, the air change rate is 0.5 l/s/m2. We recommend that a higher rate, 0.6...1.0 l/s/m2, is used for basic ventilation. The rate can be closer to 1.0 in smaller homes, and close to 0.6 in larger homes. Boosting must be possible so that a rate of 0.9...1.2 l/s/m2 can be achieved.

For example, in a 100-m2 home with four bedrooms, the air change rate should be closer to 1.0 l/s/m2, whereas an air change rate of 0.6 l/s/m2 is suitable for a basic-level house of 200 m2 and five bedrooms.

A person living in an old house may have gotten used to stuffy bedroom air over the years. However, the standard requirement of 6 l/s/person for a bedroom is not sufficient – the air flow should be doubled. The minimum fresh supply air flow rate, even for a small bedroom, is 8 l/s. The required air flow rate is further increased by dehumidifica-tion, cooling and heating.

The outdoor air flow rate is usually dimensioned by the expected number of occupants in each space or by surface area. The number of pillows in the architectural drawings cannot be used as a reliable indicator because the number of occupants can vary in both directions. When boosting is required, the minimum amount of boosting is +30%, but it would be safer if the rate could be doubled.

Therefore, the design should prepare for the maximum required. Experts recommend that the ventilation systems for detached houses should be dimensioned for air flow rates that are 1.5 to 2 times higher than the design air flow rates to cover a sufficient boosting requirement. If the system is dimensioned for air flow rates that are too low, it will be noisy and will consume a lot of electricity during boosting. The system can be adapted to the changing conditions by optimized control.

A smaller dwelling needs lower air flow capacity. However, it should be noted that a studio apartment contains all the same functions that increase the heat and moisture load as a larger dwelling. The dimensioning is higher in a smaller dwelling because the extract air flow rate is determined by the bathroom/wet rooms. The supply air flow must then be in the correct proportion to the extract air flow rate.

The air flow rates for the periods of non-occupancy may not be lower than 60% of the rates during occupancy.

After dimensioning the room-specific air flow rates, the HVAC designer ensures that the air flows are sufficiently balanced and that there is slight underpressure compared with outdoors.


5.2 Selecting the air distribution methodThe purpose of ventilation ductwork is to take the fresh air into proper spaces and con-vey the extract air to the heat recovery unit and then convey the exhaust air out of the building. It should perform these tasks quietly and in a controllable and energy-efficient manner in all conditions.

The selected air distribution method has a significant effect on how well the ventilation system is valued. Mixed flow is the most common air distribution method (the other methods being displacement, zone and piston). It is based on a high-speed supply air stream that takes the room air along, and as a result, the room air is mixed efficiently. Impurities present in the room air are diluted and the room air quality is relatively con-sistent throughout the room. Mixed flow also works well for cooling the room air.

If the ventilation system is designed in accordance with the appropriate regulations, fresh supply air is delivered to occupied spaces and the used air is extracted through the bathroom and similar, less pure wet rooms. The most secure way to ensure high-quality indoor climate is to design a system with room-specific control. It requires room-specific supply and extract air ventilation.

Transfer air routes are typically needed from dwelling spaces to corridors and further to spaces from where air is extracted. The designed pressure difference of transfer air routes must be at such a low level that it has only a small impact on air flow and room pressure levels.

5.3 Ductwork and dimensioning of ducts“When dimensioning the air ducts, the improved air flows during the periods of occu-pancy have to be taken into account in accordance with the regulations.” The National Building Code of Finland, Section D2, Appendix 1

The aim is to design the ducts to provide the best possible functionality. In addition, they should be easy to install and clean, and they should be as cost-effective to obtain and install as possible.

The air velocities in ducts for non-boosted air flows of the occupancy period are 1...2 m/s. The air velocity must not exceed 3 m/s in short ducts outbound from the ventila-tion unit.

The material is largely a matter of taste, although steel ducts remain the most popular choice. The preferences for the selected contractor may be the decisive factor.

In any case, sizing the ducts must never be affected by anyone’s preferences because it is of crucial importance for the operation and energy efficiency of the system and comfort levels.

Air change efficiency

Air change efficiency is the ratio between the lowest possible mean age of air and the mean age of air in the room at the same air flow. Mean age of air is the time for air to travel from a terminal de-vice to the monitoring point. In a mixed flow system, the efficiency is 50% when the supply air and room air are completely mixed.


In addition to the purchase cost of the ducts, the costs related to the fan energy and basic control must be taken into account when selecting the most economical solution. A larger duct is more expensive and requires less fan power. On the other hand, it enables cooling and dehumidification via ventilation. The velocity of air is also lower in a larger duct, which helps to avoid irritating noise. The noise level is something that must be discussed with the customer. Light sleepers suffer from any noise in the bedroom. In accordance with Section D2, the maximum sound level in dwelling spaces is 28 dB.

The exhaust air must be conveyed out of the building so that it does not causemoisture load to structures or unpleasant odor emissions at the exhaust. If conveyed on the roof, it may not cause snow to melt in winter.

It is advisable to use design software for the design work and dimensioning. It is impor-tant to ensure that the values entered in the software are correct. A good result can be easily obtained by following a few rules of thumb:

» Pressure loss/friction loss is below 1 Pa/m.

» The ductwork must be as simple as possible and symmetrical in terms of pressure loss (for self-regulatory operation).

» The main ducts must be as large as possible (they act as manifolds and provide a sort of reserve).

» The authority of terminal devices must be sufficient for control.

The table below presents the air flow rates and duct sizes that ensure quiet ventilation and a good SFP value.

Duct size, Ø; mm

Max. qv , l/s dwellings, radio

stations

Max. qv , l/s offices, stores

100 25 (often in dwellings 125) 35

125 40 60

160 65 100

200 120 180

250 190 280

315 320 480

400 520 800

500 850 1,400

Acoustic considerations must also be met when designing and constructing the ductwork. T-pieces must be used for connecting the terminal devices to control noise.

Large main duct

= air flow= noise


Fire compartmentation is an important consideration. A garage attached to the house is a separate fire compartment to the residential space. Apartment buildings have dozens of fire compartments because each apartment is a separate fire compartment. Therefore, we recommend room-, section- or apartment-specific ventilation because it is the best way to ensure efficient fire compartmentation. It eliminates the need for fire dampers, which are expensive and require maintenance, and insulation is easier as well. If the devices and ducts are room- and section-specific, improved controllability of the system is an added bonus.

5.3.1 Quiet as a mouse – ventilation without making a soundWith proper dimensioning of flows and efficient noise control, the ventilation system can be designed to be virtually silent.

The sound level permitted in Section D2 is often higher than the noise level experi-enced to be disturbing by occupants. Therefore, special attention must be paid to noise control at the design stage. A ventilation system that is quieter than the background noise is implemented with a ventilation rate of about 0.5.

It is advisable to utilize a silencer module for noise control whenever possible. This module is connected to the ventilation unit and its noise-damping properties on the ducts are known. Noise control can also be implemented with separate duct silencers in the supply and extract air ducts. If a silencer module is fitted, the outdoor and exhaust air ducts do not normally require duct silencers. Space must be reserved for silencers in the design.

In terms of noise control, the optimal location for the ventilation unit and silencer module is the mechanical room where the noise coming through the envelope of the ventilation unit and silencer module does not disturb living. This location also ensures easy maintenance. In a detached house, the ventilation unit may have to be located in the laundry room, for example. In any case, locating the unit on a wall adjacent to a bedroom should be avoided. When installing the unit in a laundry room, the risk of

The main duct must be as large as possible and act as a manifold.

Lämpö-, vesi- ja ilmanvaihtoverkos-to on mitoitettava niin, että johto on väljä ja venttiili ahdas.

Tällöin venttiili yksin määrittää virtaaman suuruuden, riippumatta muiden venttiilien asennosta.

Every heat, water and ventilation network must be dimensioned so that the line is large and the valve is small.

This ensures that only the valve determines the flow rate at each location, regardless of the position of other valves.


condensation must be taken into account, and anti-condensation insulation and con-densate drain facilities must be taken care of.

Noise transfer must also be taken into account. If the ventilation unit is located in the laundry room and the bedroom supply air is conveyed to the laundry room through an opening in the door sill and removed via an extract duct, the noise can disturb those sleeping in the bedroom. Because such applications require the use of an acoustic door in accordance with the requirements specified in Section C1 of the National Building Code of Finland, the bedrooms must be equipped with both supply and extract air vents. (The maximum permissible sound levels in internal spaces resulting from build-ing services equipment.)

Elegant silencer modules are available for the Enervent Pelican and Pegasos ventilation units. Modular silencers are a quick, easy and neat way to take care of the noise control of a ventilation unit. The ready-to-mount silencer module just needs to be lifted on top of the ventilation unit and the work is done. The benefits of the ready-to-mount mod-ules include the neat and uniform finish, easy installation and optimal noise control.

5.3.2 Duct insulationDuct heat losses decrease the efficiency of the heat recovery and thus contribute to the need for additional heating and cooling.

Duct heat losses can be minimized by suitable building layout and locating the ventila-tion unit and ductwork indoors so that the length of the ductwork is minimized and the ducts can be insulated easily. Ducts can also be installed in cold spaces or in the attic, for example. In that case, sufficient anti-condensation and thermal insulation of such ducts must be ensured.


It is recommended that the supply and extract air ducts are not installed in the attic space outside the vapor barrier so as to prevent moisture damage and mold growth on the ducts.

The supply and extract air ducts are located so that they are in warm spaces. They should not be located in cold attic spaces because this increases the risk of air and condensate leaks as well as unnecessary heat loss.

The importance of careful insulation of the ducts cannot be emphasized enough. Unin-sulated or improperly insulated ductwork reduces the efficiency of the entire system if the generated or recovered heat or cold energy is lost during transfer. In the worst case, it can also cause significant moisture damage if the temperature conditions of the ducts cause condensation to form on the ducts and wet the surrounding structures.

To prevent heat and cold losses, the supply air ducts routed in warm spaces must be insulated with vapor-proof insulation material, especially if the supply air is used for cooling or heating.

The insulation of the supply air duct from the ventilation unit to the terminal device must be designed and implemented so that the temperature of the air flowing in the duct does not change by more than 1 °C.

The insulation of the extract air duct from the terminal device to the ventilation unit must be designed and implemented so that the temperature of the air flowing in the duct does not change by more than 1 °C.

The outdoor air duct must be insulated. In addition, the exhaust air duct must be insulated because the temperature in the duct is below zero in the winter. Even if the extract ducts of a single-family house are routed in warm spaces, the temperature in-side the duct enclosures can be significantly lower than the room temperature. In case of any doubt, the ducts must be insulated.

The separate exhaust air duct from the kitchen must be fireproofed.

It may be necessary to lead ventilation ducts through the vapor barrier of the building envelope. The airtightness of the lead-through locations must be ensured using suitable seal components, for example, to prevent moisture present in the indoor air from enter-ing through the leaks into the insulation.

For the purpose of thermal insulation of ventilation ducts, various net and lamella mats as well as half-section and mat insulation products covered with laminated aluminum are developed. When attached with tape, these products protect the ducts from exter-nal moisture. Alternatively, pre-insulated ducts can also be used.

The choice of insulation type is affected by a number of reasons, from insulation ca-pacity to price. Ease of installation is naturally an important consideration for detached houses’ ventilation duct insulation. However, the cost of insulation of an average detached house is not large, and this is also not the right place to make savings.

Particularly in a house equipped with air conditioning (cooling and heating via ventilation), careful anti-condensation and thermal insulation of ducts is a low-cost way of ensuring the flawless operation of the building and a healthy indoor environment.


5.4 Selecting and locating the terminal devicesThe proper location of terminal devices has a significant impact on the comfort of living and use of the space.

Locating the terminal device in the central section of the building improves the air change efficiency of the space. The location and blow direction of the supply air termi-nals form a flow field in the space. The flow field is also affected by windows, heaters and extract air terminals. The terminal devices located on the external walls work well for both heating and cooling, and they provide equal flow for the entire room. However,

Ductdiameter Ø mm

Minimum insulation thickness mm. *)

∆t °C Insulation thickness mm.

5 10 20 30 40 50

63 - - 20 30 50 50

80 - - 20 30 50 50

100 - - 20 50 50 75

125 - - 20 50 50 75

160 - - 30 50 50 75

200 - - 30 50 75 75

250 - - 30 50 75 100

315 - - 30 50 100 100

400 - - 30 50 100 100

500 - - 50 50 100 100

630 - - 50 75 100 100

800 - - 50 75 100 100

1000 - - 50 75 100 100

1250 - - 50 100 100 100

Thermal insulation of round ducts

Ohje:Paloeristys on huomioitava erik -seen*) Taulukon arvot soveltuvat

ULTRA luokituksen mukaisille tuotteille keskilämpötilassa (λ 10°C < 33 mW/m°C)

Jos eriste on muuta kuin ULTRA- luokkaa, niin minimi eristepak -suus korjataan paksuuskertoimel -la (2.3).

Huom.• Paksuus määräytyy taloudelli -

sin perustein• Tilakustannusta ei ole huo -

mioitu!

Ehto:Eristyspaksuudet perustuvat:• Ilman nopeus kanavassa 1...5

m/s• Kanavan pituus enintään

30 m

• Ilman lämpötila. +20 °C• Ympäröivän tilan ilman liike -

nopeus 0 m/s• Ympäröivän tilan lämpötila

+15, +10, + 0, -10, -20,-30 °C

Huom.Paksuudet tulee AINA mitoittaa laitoskohtaisesti.

Thermal insulation of round ducts

ConditionsThe indicated insulation thicknesses are based on the following conditions:

» Air velocity in the duct: 1...5 m/s

» Maximum length of the duct: 30 m

» Air temperature: +20 °C

» Air velocity in the sur-rounding space: 0 m/s

» Air temperature in the surrounding space: +15, +10, +0, –10, –20, –30 °C

NoteThe thicknesses must ALWAYS be dimensioned separately for each appli-cation.

Instructions:Fireproofing must be consid-ered separately*) The values indicated in the table are suitable for products with the ULTRA rating at an average temperature of (λ +10 °C < 33 mW/m °C)

If the insulation is other than of the ULTRA rating, the specified minimum thick-ness must be corrected with the appropriate thickness correction factor (2.3).

Note » The decision on final

thickness is based on economic issues

» Facility costs are not taken into account!

Source: Isover


Supply air

Extract air 1

Extract air 2

Extract air 1 » Closed when bathing, otherwise

open

Extract air 2 » Open when bathing, otherwise

“closed” --> the vent is not closed but in practice all air flows through the Extract air 1 vent

A good sauna

We Finns love our saunas and think that anybody can design their own sauna – regardless of whether they have any expertise. Based on the principles of good ventilation for the sauna room, we know that the supply air inlet must be located on the wall or ceiling above the stove, and the extract air outlet is located below the benches.

the throw of the terminal device must be sufficient to reach the opposite wall to ensure efficient mixing in the heating mode. Blow from the corridor wall may cause problems with draft. Ceiling-mounted terminal devices can also be used.

The required air flow has an impact on both the number and type of terminal devic-es. The terminal devices must also be able to convey the increased air flows during boosting without generating any whistling sounds. The recommended pressure behind terminal devices is about 10...20 Pa. Terminal grilles with appropriate flow capacity must be used in higher-volume applications.


A single terminal device is not necessarily sufficient in large open spaces, even if it is ideally located. Two or more terminals must then be used to ensure optimal mixing of air.

The actual terminal devices should be carefully selected. Unfortunately a large share of the benefits and advanced properties of a high-quality ventilation system are lost if in-sufficient terminal devices are selected. It is not just comfort that is at stake. If the warm supply air is stratified in the upper section of the room without properly mixing into the room air, it impairs the air change efficiency. As a result, it also impairs the energy efficiency of the entire system and therefore increases the related costs.

A good terminal device that is suitable for the application in question has a suitable mixing performance and throw pattern, is easy to adjust and clean, and is quiet. Suffi-cient pressure difference ensures good mixing performance. The correct throw/diffu-sion pattern for the space ensures that the warm air does not remain close to the ceiling or cool air does not drop too quickly onto the occupants.

A modifiable terminal device developed for air heating and large spaces is slightly more expensive than the traditional disc valve but it offers a number of advantages: modifia-bility, excellent technical properties, and a long and narrow diffusion pattern. The price difference between a more affordable but insufficient terminal device and the terminal that provides the best possible results is usually negligible, considering the total cost of the system.

The sound level of the terminal device is an important factor, especially in bedrooms and other dwelling spaces.

The design of terminal devices matters as well. In terms of interior design, actual atten-tion has only been paid to the design of HVAC equipment in the last few years. There are terminal device options available that fit quite nicely with both antique furniture and minimalistic interiors.

The ease of ventilation duct installation must also be taken into account when selecting the terminal devices.

5.5. Fireplaces, kitchens and central vacuum cleaners

Air is also removed from a building through fireplace flues and cooker hoods. This re-moved air must naturally be replaced. In the past, make-up air for extract air ventilation and combustion air for fireplaces infiltrated through gaps in the leaky building envelope without causing any significant pressure difference. This is not possible in modern build-ings designed to be airtight. The pressure differences will become too high. Lighting a fire in the fireplace may be difficult and smoke comes in. Therefore, the supply of make-


up and combustion air must be designed and arranged separately. A competent HVAC designer can do it – guesswork will cause more problems.

The ventilation unit can supply a fair amount of make-up air for a short period of time when lighting a fire in the fireplace or using the cooker hood or central vacuum cleaner. However, make-up air should not be taken through the ventilation unit for an extended period of time because there is a risk of excessively low supply air temperatures.

To be able to control the pressure differences of the envelope of an energy-efficient and airtight single-family house, mechanical supply of make-up air for separate exhaust air flows is required. This ensures a sufficient balance of air flows at all times. Separate make-up air solutions can decrease the pressure difference of the envelope slightly, but arranging filtration and pre-heating for the supply air taken from outside is difficult. The make-up air system must be designed to meet the flow rates of the separate exhaust air and it must allow airtight closure or it must close automatically. The make-up air solution must not impair the sound insulation properties of the building envelope.

The make-up air system must be designed so that it is automated and does not require any user input.

Extraction of cooking smells quietly and without wasting energyEven in new energy-efficient buildings, the extraction of cooking smells above the kitchen range is almost without exception implemented with a cooker hood containing a fan or with a hood connected to a roof ventilator. Due to the poor smell-capturing capacity of these hoods, the extract air flow rates are high – approximately at the same level as the total extract air flow of the remaining ventilation system in a single-family house. These separate exhaust air flows can generate a high pressure difference over the building envelope. The extract air flow rate of a typical cooker hood is about 30...80 dm³/s, and the flow rate can be higher when a hood connected to a roof ventilator is used.

Cooker hoods are also quite noisy. A quieter solution is a hood connected to a roof ventilator equipped with a silencer.

The extract air flow rate generated by a typical roof ventilator is 30...100 dm³/s but it can be even higher. The higher air flow rate improves the smell-capturing capacity slightly. To avoid problems related to condensation, a damper can be fitted in the duct or the extract fan can be kept on at a low setting.

Dust removalThe extract air flow rate generated by a typical central vacuum cleaner is about 50 dm³/s. The best solution would be if the central vacuum cleaning system took care of the make-up air control. If sufficient filtration is arranged for the exhaust air of the central vacuum cleaning system, this air can be returned indoors, as is the case with the regular vacuum cleaners.


Functional fireplace

Fireplaces work properly when there is a draft in the flue and the supply of combustion air is sufficient. The building’s ventilation system and separate exhaust air flows must be implemented so that they do not impede the operation of the fireplace. Air or impu-rities from the fireplace combustion chamber must not travel into the indoor air, even when the fireplace is cold. The overpressure function of the ventilation system helps to ensure a draft in the fireplace flue. The overpressure function generates a temporary (typically 15 minutes) overpressure condition indoors, ensuring outward draft in the flue.

Combustion air supply to the fireplace must be independent of the ventilation system. This means that the combustion air is not taken from inside the house. Chimneys designed especially for energy-efficient buildings are available on the market. These chimneys are connected to sealed-unit fireplaces and they take the combustion air from outside and convey it directly into the combustion chamber. These chimneys include, for example, Rondo Air by Schiedel Savuhormistot and Iki Air by Härmä Air.

In an extremely airtight house, ventilation devices that generate high underpressure should not be used when wood is burned in a fireplace. Such devices include, for exam-ple, cooker hoods, hoods connected to a roof ventilator, and central vacuum cleaners.

5.6. Selecting and locating the ventilation unitA ventilation unit is a versatile and rather complicated piece of equipment. It contains the supply and extract air fans, extract air heat (and cold) recovery unit, air filters, possi-ble additional heaters and the required automatic control. It is responsible for distribut-ing air into every space, performing the necessary heating and cooling, and controlling the indoor air humidity and carbon dioxide levels.

Normally, only one ventilation unit is used for detached houses but often a decentral-ized system with more than one ventilation unit provides better results: the controllabil-ity of ventilation remains at a high level and the ductwork can be kept at a reasonable size. The needs in, say, a two-story home, may vary a lot: the sauna is located on the first floor and the bedrooms are on the second floor.

In commercial projects, the number of ventilation units is determined by the size of the building/number of floors, but it is also affected by the desired level of control in terms of different spaces, the desired level of preparedness for potential ventilation renova-tions, and changes in the intended use in the future.

When selecting the location for the ventilation unit, the noise emitted by the unit in the immediate vicinity must be taken into account. The unit should not be installed on a lightweight wall that amplifies the sound, or on a wall adjacent to a bedroom. Good locations include sturdy masonry walls in the laundry room or mechanical room. The necessary external water, electricity and condensate water connections should also be borne in mind when determining the location. Moreover, sufficient space must be reserved around the unit to ensure easy maintenance.


Standard


Control system

Units:• MD• eco EC

Classic

Fresh air Heat recovery Supply-air heating

Control system

Units:• MDE• MDW• eco ECE

Dynamic

Fresh air Heat recovery Supply-air cooling

Supply-air heating

Control system

Units:• MDE-CG• MDW-CG

Premium




Control system

Units:• HP eAir• MDX

Superior




Control system

Warm-water supply

Units:• HP Aqua

Dehumidifi-cation

EnergyBUS

Enervent ventilation solution is selected for the features you need


PRE- AND AFTER-HEATING SOLUTIONS


6.1 Electric and water-based pre-heatingThe pre-heater levels out the impact of the very lowest temperatures in winter and pre-vents the heat exchanger from freezing in conditions where the amount of moisture in the extract air would cause the risk of freezing when the temperature is below zero. The risk of ventilation unit freezing is increased when the fan capacity is not sufficient for removing a sufficient amount of moisture out of the building. This can be the case if the unit is run at an excessively low setting (the humidity boost feature included in the MD control system is an excellent feature to prevent this scenario) or if the unit’s capacity is not sufficient (dimensioned or installed incorrectly) for the prevailing humidity level. Let’s consider, for example, a semi-detached house with two identical homes: in one home, a retired couple manages well with a small ventilation unit, but the large family next door requires air flow rates that are threefold those of the retired couple.

» A sufficient amount of air must be supplied and extracted to be able to control the moisture load: 0.6...1.0 l/s/m2 (at a high load 1.0 l/s).

» The moisture content of indoor air should not exceed 7 g per 1 kg of air (1 kg of air = 1,000 liters).

» For the plate heat exchangers, the risk of freezing starts at a temperature of zero degrees Celsius, and for rotating heat exchangers the corresponding value is about –10...–15 °C, depending on the moisture content of the indoor air.

The electric pre-heating coil is located in the ventilation unit, upstream of the heat recovery unit. If dimensioned properly, a ventilation unit equipped with a rotating heat exchanger does not need electric pre-heating. Correct dimensioning ensures that freezing is not possible.

Fluid-based pre-heating coils also enable pre-heating and pre-cooling via ventilation for older buildings, provided that the building has mechanical supply and extract air ventilation and the possibility to utilize an existing ground circuit or install a new circuit. For more information, see Chapter 8.

6.2 Electric and water-based after-heatingFresh air must never mean the same as air that feels cold – unless the purpose is to cool the indoor air down on a hot summer’s day. In order to avoid draft discomfort, the supply air must often be heated to a comfortable temperature after dehumidification. During the heating season, heat recovered from the extract air is primarily used for heating the supply air. The more recovered heat energy can be used for this purpose, the more energy efficient the ventilation system and the entire building is.

If the recovered heat is not sufficient for heating the supply air to the desired tem-perature, the required additional heat is generated with an electric or water-based after-heating coil.


For the major part of the year, the modern, highly efficient ventilation units can heat the supply air to over +17 °C with the energy recovered from the extract air. Especially in southern Finland, after-heating is only seldom required in normal winters.

Along with the development of ventilation units (that is, improved efficiency), the ener-gy consumption of after-heating coils has decreased as well. Despite this, the after-heat-ing function in the ventilation system is not intended for heating the building, unless the ventilation system is designed to be a heat distribution system. A proper setting for the after-heater is 2 to 5 degrees lower than the room temperature, that is, +15...+19 °C.

The selection of the best possible after-heating method for a project is affected by a number of factors, such as the size and geographical location of the building, required output, heat distribution method and the selected source of heat energy.

The electric after-heating coil can be located in a duct or integrated in the ventilation unit.

When compared with the water-based after-heating coils, the electric after-heating coils are more affordable to purchase and install. Electric heating coils are also very reliable. The electric coil itself will not get damaged in case of a mains failure or circulation pump failure in the wintertime, for example.

In southern Finland, the number of days when after-heating is required is low or moder-ate at the highest. Therefore, an electric coil is a good solution, especially for single-fam-ily houses and when the required output and air flow rates are on the low side. The further north the house is located, the more days when after-heating is required can be expected. The economic efficiency of water-based after-heating is also increased as the size of the building and required output increases.

As a general rule of thumb, it can be said that electric heating coils are best for systems designed for air flow rates below 720 m³/h. For higher rates, the profitability of wa-ter-based coils should be examined.

The water-based after-heating coil can be located in a duct or will be integrated in the ventilation unit. The warm water for the water-based after-heating coil is usually taken from either the underfloor or radiator heating circuit.

A water-based heat distribution system enables the cost-effective use of water-based after-heating coils. This is especially true when the heating energy used is something other than electricity. For example, district heating can also be used for heating the supply air instead of electricity in houses connected to a district heating network.

Water-based coils are a natural solution in connection with ground-source or air/water heat pump systems and the hybrid systems of energy-efficient buildings, which enable the connection of solar collectors or water-bearing fireplaces, for example. The recov-ered heat energy generated in the building can be stored in an energy tank, from where the energy can be utilized in the building’s heating system and also in the domestic water system.

The selection between an electric and water-filled after-heater should always be con-firmed with project-specific calculations.

NOTE:

A water-filled after-heating coil must always be protected with a damper that is closed automati-cally in case of a mains failure.


Correct settings

According to Section D5 of the National Building Code of Finland (Calculation of power and energy needs for heating of buildings), the temperature for supply air can be assumed to be +18 °C if more accurate data is not available.

We recommend that +15 °C is used as the set value for the sup-ply air after-heating temperature. The supply air temperature will very seldom decrease below this value in a ventilation unit with efficient heat recovery. For the purposes of cooling in summer, the supply air demand temper-ature must be as low as possible to enable efficient use of the free cold in the outside air during the nighttime, for example.

E-value and electric after-heating

Because the energy factor for electric heating is 1.7 for the purpose of calculating the E-value, electric after-heating has an impact on the E-value. After-heat-ing coils consume only a small amount of energy at low air flow rates. If not required otherwise by the E-value, it is advisable to use electric after-heating coils for such air flow rates.

Ventilation systemVentilation system description

Pandion MDX click

Air flow supply/extract

SFP of the system

Heat recovery tempera-ture ratio

Frost protec-tion

[m3/s] / [m3/s] kW/[m3/s] – C

Main ventilation units 0.056/0.056 1.65 > 77.0 – 10.00

Separate exhaust air flows

–

Ventilation system 0.056/0.056 1.65

Annual efficiency of the heat recovery of the building’s ventilation system: 77.0%

Heating systemHeating system descrip-tion

Electric, electric underfloor heating + MDX

Production supply/extract

Distribu-tion and emission efficiency

Coefficient of perfor-mance (1)

Electricity consumption

of auxiliary devices (2)

Space and ventilation heating

85% 2.80 0.50

DHW production 1.00 92% 0.00(1) annual average coefficient of performance for the heat pump

(2) can be included in the annual average coefficient of performance for the heat pump in heat pump systems

Amount, pcs Production, kWh

Heat-storing fireplace 1 2,000

Air-source heat pump


6.3 Enervent MDX: Air-source heat pump integrated into ventilation after-heating and after-cooling

MDX is an air-source heat pump integrated into ventilation after-heating and after-cool-ing. Because it is integrated into an Enervent ventilation unit, it acts as an energy-effi-cient source of energy. The system is suitable for both new buildings and renovation projects. For more information on the MDX solution, see sections 8.7.2 and 9.1.

6.4 Enervent CHG: Ground circuit for pre-heating and pre-cooling

The CHG coil (Cooling/Heating Geo) is a lamella coil that is installed into the ventilation unit’s fresh air duct. It is connected either directly to a separate ground circuit, or to the ground circuit of a ground-source heat pump through a fluid heat exchanger. Depending on its use, it can act both as a pre-cooling and pre-heating coil in the ven-tilation system. The CHG coil helps in saving energy because it significantly reduces the consumption of heating and cooling energy in the ventilation system by utilizing free energy instead of purchased energy. For more information on the solution, see sections 8.7.1 and 11.

CHGMDX

CONTROL SYSTEMS GUARANTEE HIGH-QUALITY INDOOR AIR


The separating factor between a moderate and excellent indoor climate quality can be the ventilation system’s control system. The control system takes care of the ventila-tion system’s automatic control and adaptation to changing conditions. It enables the operation of the system to be programmed in advance and changed as necessary. At best, it enables the indoor conditions to be adjusted in accordance with the personal preferences of each user/resident. Today, ventilation control should often be included as part of other building automation, or remote control with a smartphone, for example, should be possible.

The more detailed control of the indoor climate by the ventilation unit is desired, the more complicated the control system will be. However, this should not be visible to the user.

Even the best control system does not serve its purpose if the user does not understand the system or cannot use it in the hectic pace of everyday life. Even the most detailed instruction manual does not help if the user does not bother to read it – as is often the case. If the control system appears to be complicated and jam-packed with different menus, the more likely it is that the user will not want to familiarize him or herself with it.

On the other hand, it does not matter how complicated the control system itself is if its use is so easy and simple that anyone from a young child to an elderly person can use it.

Topics for discussionIt is important to talk with the residents about what they expect from the control sys-tem of the ventilation/air conditioning system, especially when designing a ventilation system for a detached house.

» Do they want a fully automated system that does not require user input – do they want a system that can be ignored?

» Do they want the ventilation control to be as simple as possible, performed through basic functions?

» Does the group of residents include a technically-inclined person who is keen on gaining savings, measuring everything possible and keeping records?

» Is there a need for remote control of the system and if yes, in what way?

» To what building automation system should the system be connected?

» Do they want to prepare for when they are elderly?

An easy-to-use and versatile control system increases the resale value of the building.

Guidance on the use of the ventilation system should not be forgotten, and it should not be expected that going through the instructions with the assumed main user is sufficient. The control system should be talked through with every user, whether the system is installed in an office or a private home.


7.1 ECC controlThe ECC control system is a basic automatic control system designed for the Enervent ventilation units to control the key features of the unit. The ECC control panel is visually clear, simple and easy to understand. There are four fan speeds. The heat recovery can be switched on and off, and the after-heating function can be switched on, provided that the unit is equipped with an electric coil. The electric after-heating can be con-trolled in four steps. The panel also contains an indicator light for maintenance and fault status indication.

The overpressure control is in the internal controller card. The overpressure function is controlled with a separate push button.

The ECC control system has four fan speed settings on the control panel. The actual speed setting is performed on the DCC circuit board located in the unit’s electrical box. Each of the four speeds can be trimmed manually so that the fan speed is 20...100%. The pressure rates can be set with a separate control that adjusts the supply fan speed in relation to the extract fan speed.

15

1020

LTO

TEM

P

Control panel(s) are connected here(in either one).

Exte

rnal

con

trol

cco

nnec

tions

FAN

SPE

ED C

TRL

0 %

TF DIF

F

-20

%+1

0 %

S1 20 %

30 %

40 %

S2 40 %

50 %

60 %

S3 60 %

80 %

70 %

S4 80 %

90 %

100

%

TFCTRL

PFCTRL

ECC control system’s control panels ECC05E and ECC05

DCC motherboard


Fan speeds

The fan speed is indicated by the number of LED indicator lights lit on the control panel. The fan speed is selected with the button below the indicator lights. An LED indicator light flashes when in overpressure mode.

Additional heatingThe control panel for ECE units has a button for the after-heating/supply air temper-ature setting. The highest setting temperatures are not necessarily achieved with the highest fan speed settings. In normal conditions, the set value for additional heating is set to be 5 degrees lower than room temperature.

Heat recoveryThe panel has a button and an LED indicator light for the heat recovery function. It is possible to switch the recovery function off, for example, in summer when the outdoor temperature is the same as the indoor temperature, or if the purpose is to cool the in-door air by using the cool outdoor air at night. If the recovery function is kept on during a hot summer’s day, it recovers the cold from the indoor air. The recovery function can be switched off only when the outdoor temperature is higher than +15 °C. The recovery function is automatically switched on when the outdoor temperature drops below the set value.

Maintenance/fault statusThe red maintenance/fault status LED stays on constantly when the filters need to be replaced. The filter reminder is given every three months. The red LED flashes if the sup-ply air temperature downstream of the heat recovery unit is below +5 °C, the overheat-ing protector for additional heating has tripped, the emergency stop is activated, or an external contact signal has triggered an alarm.

External controlThe devices can be controlled in a versatile manner from a control subsystem or other building automation system, for example. External commands are updated to all control panels connected to the ventilation unit. Commands can be issued from the control panels or externally so that the last command remains valid.

Overpressure functionAn external potential-free spring-return push button for switching on the overpres-sure function can be connected to the terminal block of the ventilation unit’s internal controller card. During the overpressure mode, the supply fan runs at speed 4 and the extract fan at speed 2. The overpressure duration is 15 minutes.

External speed controlExternal potential-free contacts can be used to activate any available fan speed setting or to stop the fans. After stopping, the ventilation unit can be started either from the fan button on the control panel or by an external contact signal.


Emergency stop

The terminal block of the controller card has a connection for a potential-free emergen-cy stop switch for stopping the ventilation unit.

Cooling recoveryA rotating heat exchanger can be turned on and off with an external differential ther-mostat or a control subsystem, for example. The indicator light for the heat recovery function flashes when in cooling recovery mode. The heat recovery function cannot be stopped manually from the control panel when in cooling recovery mode.

External fault signalAn external fault signal can be brought to the controller card regarding, for example, a fire hazard or from the water coil frost protection. The external fault signal stops the functioning of the ventilation unit. It can be restarted by acknowledging the external fault and switching the supply voltage of the ventilation unit off and on again.

7.2 MD control systemBased on the MD control system and designed for a more demanding indoor climate control, the Enervent eAir controller is developed with ease of use in mind. It enables the residents – or, for example, the workers/users in an office – to use the ventilation system correctly: Indoor air is always fresh and healthy, and the building is a safe place to live and work.

eAir web user interface


The basic control functions are really simple to use. The ventilation system is controlled with a visually clear touchscreen controller, using operating modes. These modes include Home and Away modes. The controller also has an Eco energy-saving mode. It helps the user to reduce energy consumption by allowing the ventilation system to react more slowly to temperature changes, for example.

The controller also offers a wide range of timer functions to program the operating modes in accordance with the user’s own schedule. The timer functions enable pro-gramming on a weekly and annual basis.

Comprehensive data availableThose who are interested in technology and the state of the environment are keen on monitoring energy consumption and other measurables in their home. The measure-ments performed by the ventilation system are shown in the Measurements menu of the Enervent eAir controller. The measured data can be viewed as numbers or graphs, and the data can also be downloaded to a computer.

Easy remote controlThe ventilation unit can also be controlled remotely with eAir web, a web-based inter-face that is as clear and simple as the control panel. An access license for the eAir web service is included in the delivery. Bus control is created either via Ethernet or Modbus RTU bus.

Benefits for the technicianThe controller also features a Setup wizard function, which was developed to help the technician. The Setup wizard guides the technician through the settings of the supply and extract air flow rates for different operating modes and all other settings required for commissioning the ventilation system, and ensures a successful installation.

Operation of the MD control systemThe ventilation unit’s operating environments are Home, Office, VAK1, VAK2 and VAK3.In Home mode, the unit runs constantly by default. In Office mode, the unit runs ac-cording to a time program or an external control system. Office mode can be activated from the control panel.

VAK1, VAK2, and VAK3 operating modes are designed for large properties where the unit is running under an external control subsystem; that is, only as prompted by the external system. The VAK modes are pre-set at the factory as necessary.

FansThe fans operate at specific speed based on the prevailing mode. During commission-ing, the fan speeds (or duct pressures) are assigned for each mode. The supply and extract fans have a specific speed for each mode.

Ethernet cabling is necessary

Ethernet cabling is required for the eAir/MD remote control. If the designer includes an eAir/MD de-vice in the design, he or she must ensure that the electrical designer includes Ethernet cabling near the device. This is especially important if the device is not located in the mechanical room. Mechanical rooms are usually equipped with a modem and cross connection panel, so routing an Ethernet ca-ble to the ventilation unit is easy.


Modes affecting the fans

» Home

» Office (RH%, CO2 or temperature boosting)

» Away

» Summer night cooling

» Manual boosting

» Overpressure, cooker hood and central vacuum cleaner

» Alarm modes A and B

A supply and extract fan speed is assigned to each of these modes, not including the alarm modes in which the supply fan is always stopped and the extract fan is either stopped or runs at the minimum speed.

Constant duct pressure controlThe constant duct pressure control is an alternative to the set fan speeds. In this control system, a set pressure difference is assigned to each mode instead of a set fan speed, and the automatic control system tries to maintain this difference. Two pressure differ-ence transmitters (0...10 V / 24 V, optional accessories) can be connected to the ventila-tion unit’s motherboard. The transmitters measure the difference in pressure between the supply duct (extract duct) and surrounding air. The pressure differences are kept at the target values by controlling the fan speeds. If the pressure difference is measured over an iris damper, the method used is constant air volume control.

Carbon dioxide, humidity and temperature boosting of fansThe speed of the ventilation unit’s fans is controlled by data received from humidity and/or carbon dioxide sensors. The objective is to keep the carbon dioxide and/or humidity level in the space below the limit set in the control panel. The humidity-based control commands the fans using data from the ventilation unit’s internal humidity transmitter and possible external transmitters. One built-in humidity sensor is included in the standard ventilation unit delivery.

The ventilation unit enables the connection of three carbon dioxide transmitters and three humidity transmitters. The transmitters are optional accessories.

The carbon dioxide, humidity and temperature boost functions can be activated in the Home mode, and the humidity boosting also in the Away mode.

Returning moisture back to the room air in the wintertime is an excellent function, but overly high humidity levels should be avoided. The humidity boost function ensures the removal of excessive moisture. When humidity boosting is active, %RH boosting is activated automatically if the outdoor temperature is below 0 °C and this function is activated in the Settings menu. This function slows the heat exchanger rotation down to enable more efficient removal of moisture.

If necessary, fan speed is increased to extract excessive moisture.


Dehumidification

Dehumidification enables comfortable and healthy indoor air when the outdoor air humidity level is too high. The dehumidification function ensures that the indoor air humidity remains at the set level.

In Helsinki, for example, the climate is such that dehumidification is needed for 40% of the year. Humidity is measured as absolute humidity (grams of water/kg of air). This means that if the outdoor temperature is +15 °C and it rains (absolute humidity = 10.5 g/kg), the indoor air must be dehumidified (for example, to a level of 7 g/kg) to prevent the indoor air humidity from increasing to an uncomfortable level. When the air is dehu-midified, it is blown in at a comfortable temperature (for example, +18 °C).

1 year = 8,784 h 5 g/kg % 7 g/kg % 10 g/kg %

Helsinki 3,495 40 1,946 22 290 3

London 6,309 72 3,525 40 477 5

Ostend 6,456 73 4,046 46 1,024 12

Marseille 6,899 79 4,345 49 2,277 26

Abu Dhabi 8,719 99 8,339 95 6,463 74

comfortable

uncomfortable

still comfortable

uncomfortable

100

90

80

70

60

50

40

30

20

10

0

10 g/kg

7 g/kg

5 g/kg

14 16 18 20 22 24 26 28 30 32 [°C]57 61 64 68 72 75 79 82 86 90 [°F]

Temperature

Relative humidity [%

]

Temperature is not the only factor when it comes to comfortable indoor air. Warm and dry air feels as comfortable as cooler but humid air. The design solution is aimed at the green area of the diagram.


Extra time (Office mode)A ventilation unit operating in Office mode does not run unless a time program tells the unit to run or the extra time setting is active.

The duration of the extra time is set in the control panel, and the function can be acti-vated from the control panel or with a separate button (optional accessory). The extra time control can be aborted from the control panel. It can also be activated via Modbus.

Overpressure functionThe ventilation unit’s overpressure control can be activated directly from the control panel or with a separate button (optional accessory). It helps light a fire in the fireplace. The overpressure control decreases the extract air fan speed and increases the supply air fan speed for a duration of 10 minutes. The overpressure duration and the supply and extract fan speeds can be set in the control panel. The overpressure control can be aborted from the control panel.

The overpressure function should be kept on only for the duration of the lighting opera-tion. Other means must be used for delivering the actual make-up air for combustion. For more information on ventilation design, see section 5.5.

Manual boostingThe boosting and airing function is activated directly from the control panel. Boosting increases the speed of both fans for the desired period of time (the default setting is 30 minutes). The boosting function can be aborted from the control panel.

Cooker hood and central vacuum cleaner modes Switching on the cooker hood or central vacuum cleaner mode is possible only through an external control system (potential-free contact). The purpose of these modes is to keep the indoor pressure level the same, regardless of a running cooker hood or central vacuum cleaner.

Summer night coolingIt is advisable to utilize the cool summer nights for reducing the indoor temperature. During the summer night cooling function, the heat recovery and heating functions are switched off. The fan speeds are controlled according to the selected mode. The summer night cooling function is activated from the control panel, and it switches on and off automatically.

Weekly and annual programsTime programming enables setting a certain mode to activate at a specific time on spe-cific days of the week or between specified days. For example, the speed of the fans can be decreased by setting up a time program that sets the ventilation unit to the Away mode for the time the premises are unoccupied.

The diagram indicates the absolute humid-ity of the outdoor air in Helsinki (Finland) and Ostend (Belgium) over a period of one year. The diagram shows that if the desired absolute humidity level is below 7 g/kg, dehumidification is needed for about 40% of the year in Helsinki. On the other hand, cooling is needed only for about 20% of the average year.


Weekly and annual program settings are made in the Timer program menu. There are 20 different time program rows for the weekly program, in which the user can enter the start and end times for the program as well as the time program event according to which the ventilation unit will operate during the set period.

For the annual program, there are five time program rows in which the user can enter the start and end dates and times for the program as well as the time program event according to which the ventilation unit will operate during the set period.

Heat recoveryHeat recovery is restricted during summer if the outdoor temperature exceeds the set temperature limit of +8 °C. During this time, the heat recovery unit is at standstill unless a heating request is issued.

When the temperature is below +8 °C, the heat recovery unit operates at its full capac-ity. This may lead to contradicting situations, especially during spring when the sun heats the indoor air but the outdoor temperature is still below +8 °C. Fortunately, the temperature limit can be easily changed in the control panel.

Cooling recoveryThe cooling recovery works at the same efficiency rate as the heat recovery. The colder the indoor air is, the more efficient the rotating heat exchanger is in transferring energy. Because the rotating heat exchanger also returns some of the moisture back to the exhaust air, it helps in reducing the amount of energy required for dehumidification and cooling.

The heat exchanger rotates at full speed when the outdoor air temperature is over 1 °C higher than the extract air temperature. The heat exchanger stops when cooling is com-pleted. The cooling recovery efficiency is the same as that of the heat recovery, 75%.

Moisture recoveryMoisture recovery is one of the key features of the rotating heat exchanger. By nature, the unit tries to keep the moisture on the correct side of the structure in terms of indoor air quality. Some of the moisture in the indoor air is returned back to the dry indoor air in the wintertime, and moisture from the humid supply air is returned to outdoors with the exhaust air in summer. The higher the prevailing moisture and temperature differences are, the more efficiently moisture recovery works.

Heat recovery frost protectionThe MD control system phases the running of the supply fan based on temperature data to prevent the heat exchanger from freezing. After the risk of freezing is over, the supply fan operation returns to normal. The automatic frost protection function is enabled in the control panel. In the new passive house defrosting function, the harmful frost build-up in the ventilation unit is prevented by controlling the speed of


the rotating heat exchanger. Because the supply fan is not stopped, the ratio between the supply and extract air flow rates remains unchanged during defrosting.

Heat recovery efficiencyThe efficiency of the supply and extract air heat recovery is reported in the Measure-ments menu of the control panel.

Supply-air, extract-air and room temperature controllersThe supply air temperature is controlled by the supply air controller. If running in supply-air controlled mode, the ventilation unit tries to keep the supply air temperature at the level set in the control panel. In extract- or room-air controlled mode, the unit tries to keep the extract or room air temperature at the level set in the control panel by controlling the supply air controller set point.

The supply air controller ensures that the temperature does not drop below or rise above the limit values set in the panel.

Constant extract or room air temperature control is used when the purpose is to affect the temperature of the entire premises by heating or cooling the ventilation unit’s supply air. All units equipped with a cooling function are controlled with the extract air control method.

Room temperature control requires that the unit must be equipped with either a temperature sensor connected to the control panel (optional accessory) or a room temperature sensor connected to the MD card (optional accessory). The measurements for the room temperature control method are enabled separately from the settings.

Heating is activated when the control system sends a heating request. Cooling is on only when the control system requests cooling. They are never on simultaneously, except during dehumidification.

In the MDW units, the monitoring function for the water coil return water activates the heating function if the return water temperature drops below a set limit.

The Max. heating / Max. cooling options in the control panel quick menu activate a temporary, efficient heating/cooling function. This function forces the supply air con-troller into its maximum setting and sets the fan speeds to the Manual boosting level. Maximum heating or cooling is continued until the temperature setting in the control panel main view is reached.

AlarmsIn the alarm modes, the ventilation unit either stops completely (A alarms, such as fire alarm) or remains running in a fault state, in which the extract fan runs at the minimum speed (AB alarms when the supply air is cold). It is also possible to configure the unit so that the extract fan also stops when an AB alarm occurs.

MD motherboard


FI01EHC

ChangeNo RvDate Appr

Drawn byMW/MK

Part

EC(E)

CONTROL CHART

Part name

Check by

Pcs

Appr by

Drawing no

Name

File

Weight kg

RevA

25.10.2011Date

Product

Sheet

Ratio

ADJUSTINGCONTROL

ALARM

MEASURINGSTATUS

FI03

+

TZ+ TZA+

HRC

M1

= PHYSICAL CONNECTION= PROGRAM FUNCTION

= CABLING AND CONNECTING ON SITE (EC)

ADJUSTINGCONTROL

ALARM

MEASURINGSTATUS

TE01TE02TE10

OP HS

INTERNAL ELECTRICAL AND CONTROL CONNECTIONS

OP

TRIAC

= EXTRA EQUIPMENT

HS = OVERPRESSURE FUNCTIONOP = CONTROL PANEL (MAX 4 pcs)

eco ECEsäätökaavio

HZS

SILENCER

SILENCER

HZ = EMERGENCY STOP

S = SPEED1-4

ALARM LTOC

LTOC = COOLING RECOVERYALARM = EXTERNAL FAULT SIGNAL

RJ11

SF

10

EF

M

30M

ESESES

SWITCHSAFETY

SUPPLY

PINGVIN MODELSUNIT CENTRAL

ECE MODELS

VIKA

VIKA = ALARM OUTPUT

ES

Ensto Enervent OyKipinätie 1 | FIN-06150 PORVOOTel +358 207 528 800 | [email protected]

TE30

30FI

UNIT CENTRAL

SUPPLY

SAFETYSWITCH

FG1

M1

FG39

M39

MDX

0109.09.2014MK

1B

MD

ES

1FI

Drawn by Check by Appr by File Date PAGE

Name

Rev SheetNo Change Date Rev Appr

Weight kg

11 12 13 14 15 16 17 18 19

CONTROL CHART

ALARM

STATUS

MEASURING

CONTROL

ADJUSTING

= CABLING AND CONNECTION ON SITE (EC)

= PHYSICAL CONNECTION = PROGRAM FUNCTION

HRC75

+

SC

M

75

75

-

ES

EF

10

SF

TE32

TE05

TE01

30%RH

M

30M

OP

TE20

MD REV_C

SC10

ES

SC30

ES

MD ControlECO fans

TE10

CONTROL CENTEReAir web

TE07

BUILT-IN DEPENDING ON MODEL

CX/EV

(PE)

OUTSIDE UNIT

CONTROLTH5

TH1

TH2

SWITCHSAFETY

SUPPLY

-+

TE62

BUILT-IN CX/EV COIL PANDION, PELICAN, LTR-6,LTR-7 AND PEGASOS UNITS

CX/EV

BUILT-IN CX/EV COILPINGVIN, LTR-3, LTR-7 XL, PEGASOS XLUNITS

(PU)

OUTSIDE UNITSWITCHSAFETY

SUPPLY

CONTROL

-+

TH1

TH5TH2

+

45TZA+

45TZ+

EHCSWITCHSAFETY

SUPPLY

TE62

TE10

PDE10

PDE30

PDE10

PDE30

TE07



MD CONTROLPALLAS HP

1FI

30EF

30SC

M30

+

-

HRC75

SC

M

75

75

ES

30FI

UNIT CENTRAL

SUPPLY

SAFETYSWITCH

ALARM

MEASURING

ADJUSTING

CONTROL

STATUS

0109.09.2014JP

1-

CONTROL CHART

HZ = EXTERNAL STOP

10SF

10

10

SC

M

Drawn by Check by Appr by File Date PAGE

Name

Drawing no Rev SheetNo Change Date Rev Check

Weight kg

11 12 13 14 15 16 17 18 19

ES ES

PALLAS

HZ20

FG1

FG39

ES

PS51

EC3-D73

PDE50

TE50

COMP1

TE60

EX5

MV60

+-

+-

TE30

30%RH

TE32

TE31

10RHT

TE05

30PDE

10PDE

TZ

3x20A

+

TE07

TE10

+

ES

45TZA+

45TZ+

TE50

= CABLING AND CONNECTION ON SITE (EC)

= PHYSICAL CONNECTION = PROGRAM FUNCTION

MODBUS-RTUeAir web

OPTIONAL: AQUA FUNCTION

TE80

TL80

DHW TANK


SUPPLY-AIR COOLING/AIR CONDITIONING


8.1 Air conditioning at work and home

Today, only a few Finns would be prepared to buy a new car without air conditioning. We are also used to indoor air that is controlled in terms of temperature and relative humidity in stores and many workplaces. Still, we are expected to happily suffer in our homes during heatwave periods at +30 °C in humid air that feels thick to breathe.

The sales of air-source heat pumps, portable air conditioners and fans intended primari-ly for cooling purposes increase every warm summer, and these devices also usually sell out in the course of time. Air-source heat pumps are jointly purchased and installed in apartment buildings connected to a district heating network solely for summer use – if they were used for heating, the customer would pay for the saved energy via his or her own electricity bill.

Indoor air cooling/air conditioning must be arranged in some way in extremely airtight and very energy-efficient buildings. All heat energy provided by the sun cannot be kept outside the building with passive solar protection, and internal heat loads must be tackled in any case.

8.2 The feeling is rightRoom temperature is a measurable quantity. Operative temperature that consists of the room temperature and radiant temperature from the surfaces in the room describes more effectively what humans experience thermally. On a hot summer’s day, large window surfaces increase the operative temperature of a space much more than the actual room temperature.

A comfortable indoor temperature is always a personal experience. The generally accepted comfortable temperature of +22 °C can be a good starting point. However, people now want more freedom of choice in terms of indoor temperature.

Humidity levels also have a significant effect on how comfortable the indoor air is. A hot and humid summer’s day is uncomfortable just because of the humidity. Even if the in-door temperature remains almost the same, decreasing the relative humidity of indoor air makes the temperature feel several degrees lower than what it really is.


8.3 More problems aheadEven in low-energy houses, the indoor temperature rises notably during the periods of occupancy. Heat is generated by people, pets and active electrical equipment. The higher the internal heat load is, the earlier the cooling season starts in spring.

In Finland people are used to thinking that the heating season continues until the outdoor temperature exceeds +12 °C. In the industrial building example in section 13, cooling has been required on some sunny days in spring, even when the outdoor temperature has been as low as –8 °C. In addition, observations made in new energy-ef-ficient residential buildings show that the cooling season starts as early as sunny days in March.

By the bookThe building regulations on thermal comfort in summer require that the building must be designed and constructed so that adverse heating of spaces is eliminated. There is very little room for interpretation: The room temperature in summer must not exceed the cooling limit of +25 °C specified for the building type for over 150 degree hours in summer. (The National Building Code of Finland, Section D2 (2012), page 6 and Section D3 (2012), page 9).

comfortable

uncomfortable

still comfortable

uncomfortable

100

90

80

70

60

50

40

30

20

10

0

10 g/kg

7 g/kg

5 g/kg

14 16 18 20 22 24 26 28 30 32 [°C]57 61 64 68 72 75 79 82 86 90 [°F]

Temperature

Relative humidity [%

]

Temperature is not the only factor when it comes to comfortable indoor air. Warm and dry air feels as comfortable as cooler but humid air. The design solution is aimed at the green area of the diagram.


8.4 A variety of methods

The cooling requirement of an energy-efficient, modern single-family house must be minimized by using passive methods. The most important methods are solutions that offer protection from the sun. Direct sunshine through windows can be restricted by using windows of reasonable size, solar control glazing and structural solar protection. The primary methods include broad overhang of the eaves and balconies that provide shade, external louver structures, awnings and Venetian blinds on windows. Structur-al methods also include the improvement of thermal insulation and air tightness of the building envelope to prevent the heat stored in the structures from entering the building.

The more efficient the solar protection is, the easier it is to cool the indoor air to a com-fortable level with a mechanical ventilation system.

Delivering the cooler outdoor air indoors is usually enough to keep the indoor tempera-ture at a comfortable level. When the indoor air is cooler than the outdoor air, the access of hot outdoor air through ventilation is prevented by using the ventilation system’s heat recovery unit for cold recovery.

In spaces where the heat loads are especially high, constant air volume ventilation may have to be supplemented by room-specific cooling equipment: chilled beams, fan coil units or – especially on renovation projects – air-source heat pumps.

8.5 Determining the demand for cooling energyWhen a customer wishes to have indoor air cooling/air conditioning or a constant room temperature in all seasons, they are usually not interested in how this can be fulfilled. Terms like comfort cooling, cooling and air conditioning do not necessarily say anything to the customer – not even if the end user is represented by a developer.

But the designer must understand what the goal is and how and at what cost it can be achieved.

Determining the cooling energy demand of a building with the traditional “manual” methods is very challenging in the current building industry. Previously, the basic rule was that the cooling season starts when the indoor temperature exceeds +25 °C and the heating season starts when the indoor temperature drops below +21 °C, but this cannot be applied anymore. The best way to calculate the cooling energy demand is to model the building in an efficient calculation and design software that calculates the cooling energy demand dynamically, moment by moment.

In practice, the current regulations on energy performance require that dynamic modeling is used for all buildings other than single-family houses. The cooling energy demand of a detached house can be estimated without modeling, provided that the internal loads – people, equipment and lighting – and the heat load through windows are taken into account.

The structural and passive methods (energy-efficient windows with solar control, broad overhang of the eaves, awnings, etc.) are the primary methods that must be used first to


Comfort cooling 1 l/s/m2

Cooling 2 l/s/m2

Air conditioning 3 l/s/m2

reduce the heat load from the sun.

But these methods are not sufficient in all conditions and for all residents. When the structural methods are utilized and thus cooling energy demand is minimized, cooling integrated into the ventilation system is the simplest, the easiest to implement and in most cases also the most cost-effective method for cooling indoor air.

It is advisable to include dehumidification and cooling in the design as early as at the beginning, because adding these properties afterwards requires that the duct sizes are increased or a second ductwork with appropriate anti-condensation and thermal insulation is routed alongside the first ductwork.

If indoor air cooling is ramped up to air conditioning, the air flow rate must be tripled (1 to 3 l/s/m2). In a 100-m2 house this equals 300 l/s.

Cooling via supply air is more comfortable than cooling implemented with separate fan coil units. It also distributes the coolness into all rooms more efficiently and does not increase the amount of technology in dwelling spaces or the number of maintenance items in general.

When determining the cooling energy demand, the external and internal heat loads must naturally be taken into account but the designer must also consider the sources of internal heat loads and how these loads are generated. An estimation of these factors is not sufficient. A single-family house may be empty in the daytime every weekday. Another home may be used as place for providing day care for a number of other parents’ children. Large families may have bedrooms that accommodate more than one child. Or the family can breed big dogs who spend all day indoors. The use of electrical equipment can also vary a lot.

Therefore, the dimensioning must always be based on the peak demand. Only then can the designer optimize the system so that it also operates in a cost-effective manner.

Especially in larger buildings, such as offices and hotels, the best comprehensive cool-ing solution is to use both the ventilation system and local equipment, such as fan coil units and ceiling panels. This may also be the best solution for the use of space. The air flow rates and therefore the duct sizes remain at a reasonable level if the entire cooling energy demand is not covered by the use of flowing air. The supply air will also be cool and dry in this case. The final cooling is carried out by a ceiling panel, for example. The building’s cooling system operates in the best possible way because the local cooling equipment can operate more efficiently when the air to be cooled is already dry (lower dew point).

Let’s look more closely at the transfer of energy to a flow – air or water. The amount of sensible energy flow is calculated using the following equation:

Q = ρi x cpi x qv x ∆Tρi = air density, 1 kg/m3

Cpi = specific heat capacity of air, 1.2 kJ/kgCqv = air flow, l/s∆T = temperature difference (22 °C – 13 °C)

Ventilation unit temperatures Energy report for zone “Ventilation unit”

Month Q_HEAT Q_COOL Q_REHEAT Q_RECOOL Q_HUM Q_FANS1 1017.0 0.0 2018.0 0.0 0.0 123.8.2 919.6 0.0 1881.0 0.0 0.0 111.73 719.4 0.0 1810.0 0.0. 0.0 124.24 174.3 0.7 1285.0 0.0 0.0 121.05 30.3 80.5 773.7 0.1 0.0 126.06 0.0 172.6 383.4 0.6 0.0 122.67 0.0 376.0 208.8 7.6 0.0 127.08 0.0 286.9 313.6 .3.0 0.0 126.89 12.4 36.5 721.9 0.1 0.0 122.0

10 301.4 0.6 1288.0 0.0 0.0 125.111 815.4 0.0 1697.0 0.0 0.0 120.312 935.7 0.0 1887.0 0.0 0.0 124.0

Total 4925.5 953.8 14267.4 11.5 0.0 1474.5

kWh (sensible and latent)


The total cooling power is calculated with the change in enthalpy, because in a cooling situation the air is dehumidified due to condensation and therefore the amount of energy the air contains is changed:

Q = ρi x Cpi x qv x ∆Hρi = air density, 1 kg/m3

Cpi = specific heat capacity of air, 1.2 kJ/kgCqv = air flow, l/s∆H = change in enthalpy (55 –33) kJ/kg

In this equation, we can affect two variables. The density and specific heat capacity are constant values. Only a little can be done to the temperature difference (dT). For exam-ple, if the outdoor design condition of +27 °C/50% RH prevails, our minimum supply air temperature is +13 °C, and if the desired indoor temperature is +22 °C, the temperature difference is +9 °C. On the other hand, we can affect more on the air flow rate delivered to the space through the capacity of fans and ductwork. The table below shows the impact of air flow rate on the capacity:

Air flow

(liters)

liters/m2

Sensible capacity

(W)

Total capacity (sensible +

dehumidifica-tion) W

Feel Comments

100 1 1,080 2,640 Comfort cooling

Helps to reduce the impact of the highest

heat load peaks; requires additional

cooling at high loads (for example, a sep-arate air-source heat

pump)

200 2 2,160 5,280 Cooling Cools down the indoor air and keeps it comfortable; if the

internal loads increase notably, additional

capacity is required.

300 3 3,240 7,920 Air condi-tioning

Can maintain the desired temperature

(+22 °C) at the design condition in summer

(design condition: +27 °C/50% RH)


8.6 Controlled humidity

When determining the cooling/air conditioning energy demand, the impact of the relative humidity level must also be taken into account. If the relative humidity of air can be brought down to a comfortable level, its temperature feels a degree or two lower – even if the actual temperature remains the same. Thanks to dehumidification, less cooling is required and the air flow rates can be lower. Therefore, dehumidification is a low-cost way of making the indoor air feel cooler: decreasing the temperature to +21 °C is not necessary when dry air at a temperature of +25 °C feels pleasant. The dehumidifi-cation function integrated into the ventilation unit also supports separate/local cooling equipment. If dehumidification is carried out by the ventilation unit, the local cooling equipment does not need to dehumidify the air – its capacity can be used entirely for cooling.

About 33% less cooling power is required at +25 °C/50% (a) compared with +21 °C/40% (b)

1. Outdoor air; 2. After dehumidification (cooling coil); 3. After after-heating; 4. Indoor air

Mollier diagram for humid air

0,000 0,005 0,010 0,015 0,020 0,025

Vesisisältö, x, (kg/kg)

Entalpia, i, (kJ/kg)

-20

-10

0

10

20

30

40

50

60

70

0,1 0,2 0,3 0,40,5

0,6

0,7

0,80,91,0

8090

100110

120

130

140

Kuiv

an lä

mpö

mitt

arin

läm

pötil

a, T

, (°C

)

50

45

40

35

30

25

20

15

10

5

0

-5

-10

-15

-20

4a

2a

2b

3b

4b 3b

1

Water content, x, (kg/kg)

Enthalpy, i, (kJ/kg)

Tem

pera

ture

mea

sure

d w

ith d

ry th

erm

omet

er, T

, (°C

)

Moreover, sufficiently dry indoor air helps keep the surface materials, furniture and building structures in good condition. Dehumidification can remove moisture from the indoor air at a rate of up to 5 l/h.

In a ventilation system, dehumidification is implemented so that the supply air is first cooled down (the minimum temperature being +7 °C), causing the moisture to condense. The resulting condensate is removed to the sewer system. Then the air is


Tip for the customer

An overly frugal customer may try to save money in the wrong places. The Away mode of the ventilation system must not be set so that the system and its cooling function are almost stopped. Let’s think, for example, of a small refrigerator that is switched off. Despite its small size, it takes quite a long time before it cools down to a temperature of +5...+6 °C after it is switched on. Naturally, a large space the size of a detached house cools down even more slowly. It is more reasonable to keep the cooling/air condition-ing function on at all times – the indoor temperature remains constant.

heated with an after-heating coil, for example, to a temperature of about +18 °C. In the Enervent Aqua series units, the heat energy generated during cooling is recovered and stored in an energy bank from where it is used to heat the after-heating coils. The CG-W unit enables the temperature to be increased in a cost-effective way with a water coil, the heat source of which is a ground-source heat pump.

The system must be dimensioned carefully. If the system is undersized, all cooling pow-er goes for dehumidification and no capacity is left for cooling. A good rule of thumb is to increase the power rating by 3 kW. The unit takes 1 kW, duct loss amounts to 1 kW, and the final 1 kW is left for the purpose of cooling the indoor air.

The selection of the terminal devices must also be taken seriously because they must operate well for both heating and cooling purposes. The cooled air must be blown along the ceiling (Coanda effect) as far as possible so that it is mixed with the warm air in the room and cools the room air in a comfortable way.

The insulation of ducts must be sufficient to prevent any problems with condensation.

8.7 Enervent solutions for indoor air cooling/air conditioning

8.7.1 CG – ground-source cooling coil CG (Cooling Geo) is a ground-source cooling coil to be installed downstream of the heat recovery unit in the ventilation system.

The cool fluid in a ground-source heat pump system installed for heating the building and domestic hot water can be used to cool down the supply air in summer. The best cooling efficiency is gained if the working fluid is circulated in a drilled energy well.

Ground-source cooling is a highly energy-efficient method of cooling. It also improves the efficiency of the ground-source heat pump because it transfers heat energy into the well in summer.

CG control automation can be used in all Enervent MD ventilation units. There are three alternative configurations.

The output of the cooling coil can be regulated by controlling the fluid flow. The heat pump system’s suitability for this must be checked with the heat pump manufacturer. The automatic control system includes the relay needed for starting the fluid pump of the ground-source heat pump and the 3-way valve and actuator needed for cooling.

SOLUTION TO THE GROUND

P1 SOLUTION PUMPCG COOLING COIL

AB

3x1.5s

P1

UNINSTALLEDDELIVERED

FUSE BOX

3x1.

5s

A

TL50SV50

2x2x

0.5

ON/OFF CONTROL

(POTENTIAL FREE

CG CONTROL

OF THE CIRCULATION PUMP

CONTACT)24/0-10VDCINPUT/CONTROL

P2

SOLUTION FROM THE GROUND

CONDENSE WATER DRAIN

B (BELIMO TR24-SR)

SV50, 3-WAY VALVE(BELIMO R3...)

TL50, ACTUATOR

SUPPLY AIR TO THE ROOMS

VENTILATION UNIT DELIVERY

SHUTTER VALVE

ONE WAY VALVE

THERMOMETER

CIRCULATION PUMPP2


Temperature regulation is performed by the ventilation unit’s automatic control system. The 3-way valve and actuator are installed on the incoming ground circuit pipe. They direct the fluid flow to the cooling coil as necessary.

In the second alternative, the automatic control system includes the relay needed for starting the circulation pump of the ventilation unit’s cooling coil and the 3-way valve and actuator needed for cooling. Temperature regulation is performed by the ventila-tion unit’s automatic control system. The fluid pump is not started during cooling. A separate pump group is constructed in the vicinity of the ventilation unit’s cooling coil to circulate the cool working fluid.

In the third alternative, the output of the cooling coil is regulated by controlling the fluid temperature. The return pipe of the ventilation unit’s cooling coil is connected to the return pipe of the ground circuit. The automatic control system includes the relay needed for starting the circulation pump of the ventilation unit’s cooling coil and the 3-way valve and actuator needed for cooling. Temperature regulation is performed by the ventilation unit’s automatic control system. The fluid pump is not started during cooling. A separate pump group is constructed in the vicinity of the cooling coil to circulate the cool working fluid.

8.7.2 Enervent CHGThe CHG coil (Cooling/Heating Geo) is a lamella coil that is installed into the ventilation unit’s fresh air duct. It is connected either directly to a separate ground circuit, or to the

SHUTOFF VALVE

LINE-ADJUSTMENT VALVE

P1

P2

TL50

B

AB

SV50 A

CHG COIL

AIR TO THE VENTILATION UNIT

CONSTANT INLET TEMPERATURE / VARIABLE FLUID FLOW


CHG DELIVERY

DELIVEREDUNINSTALLED

3x1.5s

CHG-CONTROL

2x2x0.5

ON/OFF CONTROL OF FLUID PUMP (POTENTIAL-FREE CONTACT)

24/0-10VDCSUPPLY/CONTROL

ELECTRICITY DISTRIBUTION BOARD ELECTRICITY DISTRIBUTION BOARD/HAND PUMP

CIRCULATIONWATER PUMP

P1

P2 FILLING PUMP

THERMOMETER

SV50, 3-WAY VALVE(BELIMO R3...)

TL50, ACTUATOR(BELIMO TR24-SR)

SAFETY VALVE

PRESSURE GAUGE

EXPANSION TANK

GROUND CIRCUIT

Basic diagram of the CG system

Basic diagram of the CHG system


ground circuit of a ground-source heat pump through a fluid heat exchanger. Depend-ing on its use, it can act both as a pre-cooling and pre-heating coil in the ventilation system. It is an excellent choice as a support system for any heating system. For more information on this system, see Chapter 10.

8.7.3 Enervent MDXMDX is an air-source heat pump integrated into ventilation after-heating and after-cool-ing. Because it is integrated into an Enervent ventilation unit, it acts as an energy-effi-cient source of energy. The system is suitable for both new buildings and renovation projects. For more information, see section 9.1.

AIR TO THE

HEAT PUMP

OUTSIDE UNIT


SAFETY SWITCH

EVAPORATOR COIL

4x1.5s6x0.5

AIR GOING TO THE ROOMS

VEABELECTRICAL DUCT HEATER

ELECTRICAL DUCT HEATER

POWER SUPPLY

HEAT PUMP

CONTROLLER

AIR FROM THE HRW

2x0.

5

2x0.

5

2x0.

52x0.5

PAC-IF011/12B-E

2x0.5

POWER SUPPLY

SAFETY SWITCH

= CABLING ANDCONNECTIONS SAFETY SWITCH

3x1.5s

POWER SUPPLY

10A, 230VAC, 50Hz

3x1.5s

SEE TABLEFUSE BOX

VENTILATION UNIT

ON SITE (EI)FOR CONNECTIONS SEESEPARATE WIRING DIAGRAMS

Enervent eAir

CONTROL PANEL

RJ4P4Ccable

SEE TABLE

ELECTRICAL BOX

TH1The sensor afterthe supply air coil (evaporator coil).

ELECTRICAL DUCT HEATERCV 16-09-1MQXL (900W) 1x10 A, 230 VAC, 3x1.5sCV 16-12-1MQXL (1200W)CV 20-15-1MQXL (1500W)

1x10 A, 230 VAC, 3x1.5s1x10 A, 230 VAC, 3x1.5s

SUPPLY

CV 20-18-1MQXL (1800W) 1x10 A, 230 VAC, 3x1.5sCV 25-30-1MQXL (3000W) 1x16 A, 230 VAC, 3x2.5sCV 25-50-2MQXL (5000W) 2x16 A, 400 VAC, 4x2.5s

TH2The sensor forthe lowest pointof the �uid pipe

TH5Temperature sensor for coil pipe(Installed at 2/3 height of the coil)

TE10Supply airsensor(to the MD

The sensors TH1, TH2 and TH5 arepreinstalled into the unit at the factory.

HEAT PUMPCOMP 1 - PUHZ-RP35 1x16 A, 230 VAC, 3x2.5s

SUPPLY

COMP 2 - PUHZ-RP50 1x16 A, 230 VAC, 3x2.5sCOMP 3 - PUHZ-RP60 1x20 A, 230 VAC, 3x4sCOMP 4 - PUHZ-RP71 1x20 A, 230 VAC, 3x4s

moder board)

TH1

TH2

TH5

TE10

8.7.4 HP eAir for cooling Extract-air-source heat pump HP is integrated in the ventilation unit, and it takes energy from the extract air, just as the name suggests. Combined with a rotating heat exchang-er, the extract-air-source heat pump can recover almost all the heat energy present in the exhaust air and return it for heating. Its annual efficiency of heat recovery can be as high as 95%. For more information, see section 9.2.

Basic diagram of the MDX system


8.8 Drain connection for the ventilation unitA condensate drain connection must be provided for all ventilation units equipped with a cooling coil. This connection is recommended for ventilation units in general. Con-densate is generated when the air cools down, such as in winter, when humid indoor air comes into contact with the heat exchanger cooled by outdoor air.

The condensate pipe must not be directly connected to a sewer system! Condensate should be led to a floor drain using a declined pipe with a minimum diameter of 15 mm and equipped with a water seal. The entire pipe must run below the bottom of the ventilation unit, and it must not have any long horizontal sections or more than one water seal. If the unit is equipped with more than one condensate drain outlets, each outlet pipe must have a dedicated water seal.

Because there is a vacuum inside the ventilation unit, the difference in height (A) between the condensate drain level and the water seal drain level should be at least 75 mm, but in any case no less than the vacuum in millimeters divided by 10 (for example, a vacuum of 500 Pa -> 50 mm).

The recommended minimum height of the water seal water column (B) is 50 mm, but in any case no less than the vacuum in millimeters divided by 20 (for example, a vacu-um of 500 Pa -> water column height 25 mm).

In duct coils, overpressure will prevail, and therefore the recommended height between the condensate drain level and the water seal level is 25 mm for duct coil condensate drains. The recommended height of the water seal water column is 75 mm, but in any case no less than the pressure in millimeters divided by 10 (for example, an overpressure of 500 Pa -> water column height 50 mm).

The water seal must be filled with water before the ventilation unit is put into use. The water seal may also dry up if water is not accumulated in it. In this case, air may start to flow in the pipe and prevent water from entering the water seal, which may cause a disturbing bubbling sound.

A

B

HEAT PUMPS

The integration of heat pumps into a ventilation system enables the energy-efficient heating of indoor air. Combined with a rotating heat exchanger, the heat pump solution improves the annual efficiency of heat recovery further. This combination can act as the main heating system for most of the year in buildings that are especially energy-ef-ficient. In this case, no separate heat distribution system is required in addition to the ventilation system. However, underfloor heating or towel radiators are required in wet rooms, and a comfort heating system should be considered for tiled floors. For more information on air heating, see Chapter 10.

9.1 Enervent MDX – Air-source heat pump integrated into ventilation after-heating and after-cooling for heating and cooling

Enervent MDX is an air-source heat pump integrated into ventilation after-heating and after-cooling. Because it is integrated into an Enervent ventilation unit, it acts as an energy-efficient source of energy. The system is suitable for both new buildings and renovation projects.

During the heating season, the rotating heat exchanger recovers up to 75%* of the heat energy present in the extract air. This energy is transferred back via the ventilation ducts to heat the indoor air. In addition to the purpose of after-heating the supply air in winter, the heat pump can also be used for covering some of the building’s addi-tional heating energy demand in an energy-efficient way. Moreover, the rotating heat exchanger recovers moisture from the extract air in the wintertime, thus keeping the indoor air humidity at a healthier level.

The most energy-efficient solution is to use this system in a low-energy or passive house. Apart from the passive and zero-energy houses, other heating sources are also required. The heat pump integrated into ventilation after-heating works well with all heating sources and heating systems.

The heat pump integrated into ventilation after-heating and after-cooling can cool the indoor air efficiently in summer – similarly to a separate air-source heat pump – but it does not require separate indoor units. Cool air can be delivered to rooms through the ventilation system’s terminal devices evenly and comfortably, without any draft discom-fort or noise generated by indoor units.

The unit’s rotating heat exchanger recovers the cold energy and can utilize the cool outdoor air for cooling during the nighttime.

A combination unit saves on installation costs. The air is distributed evenly because no separate supply air units are required.

HEAT PUMPS

* The efficiency of heat recovery is highly dependent on the calculation method used. In the weather conditions prevailing in southern Finland, the annual efficiency of heat recovery of the Enervent units is 75%. On the other hand, the corresponding efficiency result is 85% if the methods by the German Passive House Institute, the leading certification center on energy efficiency in Europe, are applied.

HEAT PUMPS

A heat pump integrated into ventilation after-heating and after-cooling can be fitted to most Enervent’s ventilation unit frames. An evaporator coil is installed inside the ventila-tion unit or in the supply air duct, and an outdoor air unit is installed outside the building.

All MDX systems feature a compressor driven by a permanent-magnet synchronous motor, and they use R410A refrigerant for maximum efficiency.

Because the heat pump integrated into ventilation after-heating and after-cooling requires an outdoor unit, it cannot be used in projects where such a unit is not allowed on façades or restrictions are set on sound levels.

Issues to be noted in design and installationThe ventilation unit is dimensioned and selected so that sufficient heating and cooling power is ensured. Particularly for the purpose of cooling, this means that the ventilation air flow rate must be higher than the minimum level specified in Section D2. The capac-ity and ducts must be dimensioned on the basis of cooling purposes.

The selection of the unit must always be based on the project-specific dimensioning and requirements, but also on the personal preferences of the residents.

The system is designed and implemented so that its operation is well-balanced and quiet in both basic ventilation and boosted ventilation for cooling.

When dimensioning the system, it must be noted that basic ventilation must be achieved at a fan speed of 50...60%, and cooling boosting at a fan speed of 70...100%. The ductwork is designed so that in cooling mode, the boosting air volume used can be delivered at a high velocity but without the related noise disturbance. For a table showing the sizing the ducts, see page 41.

The selected terminal devices must also work in cooling mode.

The ducts must be properly insulated. The role of insulation is even more important when the ventilation unit is equipped with cooling.

Pelican MDX qv = 160 l/s Design conditions: Summer, +24 °C, RH 60%, AH 11 g/kg

+22 °C

+23.5 °C+24 °C

+13 °CEXTRACT

OUTDOOR

EXH

AU

ST

SUP-PLY

+22.5 °C

Separate outdoor unit

Hot air out

Refrigerant pipes

Electric heating coil

Rotating heat exchanger

Filter

Evaporator coil

Fan

HEAT PUMPS

9.2 Enervent HP eAir – Integrated extract-air-source heat pump for heating and cooling

Extract-air-source heat pump HP is integrated in the ventilation unit, and it takes energy from the extract air, just as the name suggests. Combined with a rotating heat exchang-er, the extract-air-source heat pump can recover almost all the heat energy present in the exhaust air and return it for heating. Its annual efficiency of heat recovery can be as high as 95%.

Because the integrated extract-air-source heat pump does not require a separate out-door unit, it is also suitable for sites where the installation of outdoor units is restricted by regulations on façades. The system is suitable for both new buildings and renovation projects.

In cooling mode, it cools down the supply air and transfers the excess heat to the waste air removed from the premises. It also removes moisture from the supply air in cooling mode, causing the room air to feel more comfortable even if the actual decrease in the indoor air temperature is just a few degrees.

In cooling mode, the valve in the unit’s refrigerant circuit is automatically switched to the opposite position than when in heating mode. This reverses the direction of the process and the supply air coil acts as an evaporator.

The system utilizes heat in two stages. Heating the outdoor air starts in the rotating heat exchanger unit, after which the air is delivered to the house via the extract-air-source heat pump. Both the extract-air-source heat pump and the heat exchanger unit recover heat energy from the extract air and transfer it to the supply air.

Thanks to the combined effect of the rotating heat exchanger and heat pump, the exhaust air temperature can be as low as –20 °C. Because the air the heat pump uses for heating is already warm, the unit’s efficiency is excellent.

Due to the rotating heat exchanger, frost build-up is not a problem, and separate additional heating is not usually needed for comfort, even if the outdoor temperature is as low as –15 °C.

Pegasos HP qv = 290 l/s Design conditions: Winter, –10 °C

+3 °C

+22 °C

–7 °C

–10 °C

+29 °CEXTRACT

OUT-DOOR

EXH

AU

ST

SUP-PLY

+/– 0 °C

+23 °C

+29 °C

Fan


Filter

Evaporator coil

Compressor

NOTE:

The extract air temperature in the building must be at least +20 °C in order for the heat pump to op-erate efficiently. If it appears that the extract air temperature will be below +20 °C, a heating coil that is available as an option must be installed in the extract air duct.

HEAT PUMPS

Issues to be noted in design and installation

The ventilation unit is dimensioned and selected so that sufficient heating and cooling power is ensured. Particularly for the purpose of cooling, this means that the ventilation air flow rate must be higher than the minimum level specified in Section D2. The capac-ity and ducts must be dimensioned on the basis of cooling purposes.

The system is designed and implemented so that its operation is well-balanced and quiet in both basic ventilation and boosted ventilation for cooling.

When dimensioning the system, it must be noted that basic ventilation must be achieved at a fan speed of 50...60%, and cooling boosting at a fan speed of 70...100%. The ductwork is designed so that in cooling mode, the boosting air volume used can be delivered at a high velocity but without the related noise disturbance.

The selected terminal devices must also work in cooling mode.

The ducts must be properly insulated. The role of insulation is even more important when the ventilation unit is equipped with cooling.

9.3 Enervent HP Aqua – Integrated extract-air-source heat pump heats water

Especially when the indoor air is cooled down in summer, the heat pump process gen-erates waste energy that cannot be used and therefore is removed with the exhaust air. HP Aqua utilizes this energy, which would be otherwise wasted, by transferring it using a heat exchanger to an energy bank (energy tank). From there, the stored energy can be used in a water-based heating or cooling system or for heating domestic hot water.

The extract-air-source heat pump also utilizes the energy recovered from the processing of moisture loads. The energy contained in the moisture load generated by showering and saunas – or by production processes in commercial projects – is stored in an energy tank. Therefore, this solution is an excellent choice not only for residential buildings but also for industrial buildings and stores where the need for dehumidification and cooling of indoor air can be high at times. An example of both cases can be found in Chapter 13.

Pallas HP Aqua KI W qv = 450 l/s Design conditions: Fall, winter, spring, air recirculation function

Warm water

Cold water

+20 °C +28 °CEXTRACT SUPPLY

FanFilter

Dampers closed

Aqua


Evaporator coil

Water coil

Circulation air damper

open

Compressor

HEAT PUMPS

By utilizing the EnergyBUS, control of the building’s heat loads and energy consumption can be performed with one system. For example, the Enervent Pallas HP Aqua circu-lation air unit is designed to take complete care and control of the building’s indoor climate, heat recovery, production of domestic hot water, and water cooling. Ensto Enervent’s EnergyBUS fulfills the dream shared by every designer and builder to have a comprehensive solution that is both simple and reliable.

EnergyBUS can be installed and implemented in any building size. Example cases of an industrial building (new building), grocery store (renovation) and a new detached house can be found in Chapter 13. A flexible system can be tailored to need. In a detached house, the need for heating and cooling depends on the energy efficiency of the building, but the demand for hot water is higher than in, say, a grocery store.

The need for indoor air dehumidification and cooling will also continue to increase in residential buildings. In grocery stores, energy efficiency requirements state that doors must be retrofitted to existing refrigeration equipment, which in turn results in excessively high relative humidity of indoor air, especially in summer. Open refrigeration equipment have contributed to the dehumidification of indoor air, but if the equipment is fitted with doors, dehumidification must be performed entirely by the ventilation system.

Moisture is also generated in many production facilities in normal operations.

The need for cooling in energy-efficient buildings can be reduced by architectural and structural (passive) means, but also by ensuring the correct moisture balance of indoor air. The higher the relative humidity is, the more hot and uncomfortable it feels. By maintaining the indoor air humidity at the optimum level, the indoor temperature can be kept a few degrees higher without it feeling uncomfortable. Proper air humidity con-trol is also good for interior materials, furniture and the operation of house structures.

HEAT PUMPS

In an energy-efficient building, energy that has already been gained is recovered and reused as efficiently as possible, whether this energy was purchased or free. Free energy includes thermal radiation from the sun and the heat energy generated by the use of the building by people, pets and equipment, for example. This free energy contributes to the heat load, and this energy was exhausted to outdoors as waste heat in the past.

For the time being, the energy lost down the drain along with greywater is still waste energy, but by utilizing the EnergyBUS all other heating and cooling energy can be recovered and reused in the most efficient and economical way in terms of the building and its use.

The heat load and heating need in a building is not necessarily distributed evenly. For example, heating need is high during the night in winter, and excess heat is generated in office buildings during the afternoon in particular when all workers are at work and all computers and other equipment are switched on. One side of a building may require more heat and the other may have excess heat. Energy is purchased for one side and wasted on the other.

Let us consider, for example, a normal detached house. A heated sauna may have excess heat, but the bedroom at the rearmost corner of the house requires heating. An industrial building may have machines generating so much heat that they require cooling, while the workers in the office rooms feel cold.

Ensto Enervent’s EnergyBus enables the excess energy to be transferred to where it is needed. The internal heat load of the building is utilized first, and energy is purchased from outside only when it is really needed.

The EnergyBUS transfers the recovered energy at the right time to where it is needed. The recovered heat (and cold) energy is stored in an energy bank (energy tank) from where it can be used to heat or cool the building via ventilation when needed. The energy can also be used for a water-based heating system or for heating domestic hot water. The recovered energy is automatically transferred to where it is needed or stored in the energy tank for later use.

COMFORTABLE AND ENERGY-EFFICIENT AIR HEATING

Air heating has made a comeback, along with the increased focus on energy efficiency in construction. Constructing a water-based heat distribution system is a much too ex-pensive investment in passive and zero-energy houses, when all or at least the majority of the heating energy can be distributed throughout the building with the supply air.

Heating the supply air is controlled with a room thermostat, and the typical supply air temperature in the winter is +25...+35 °C. Because the temperature control system can react quickly to varying heat loads, the efficiency of the heat distribution system is very high.

Although the air heating system does not necessarily require an underfloor heating system or water-based radiators, underfloor heating and/or a towel radiator is required in wet rooms. Moreover, a comfort underfloor heating system is recommended for rooms with tile floors.

10.1 Enervent Pingvin Kotilämpö unitAs detached houses were becoming more airtight due to the 1970s energy crisis, a functional and simple ventilation system was also needed. Air heating that provided both ventilation and heating in one package was an excellent solution. As the name suggests, the air heating system heats the building with warm air that is distributed to different rooms through air ducts. From the air ducts that run in the base or other structures of the building, the warm air is transferred to the rooms through air grilles that are located in or near the floor. This method works well: the floor is kept warm and the warm air rises according to the principles of physics.

The original air heating units were combinations of ventilation and circulation air units.The Enervent Pingvin Kotilämpö unit was designed to replace the Valmet Kotilämpö unit, which was the most popular air heating unit of its time. It can naturally be used for replacing other old air heating units as well. The modern version also includes a more efficient heat recovery unit, which makes the system much more energy efficient. Comfort levels are also improved when the ventilation system is more efficient and can be controlled in a versatile manner.

The old Valmet Kotilämpö unit is replaced by a Pingvin Kotilämpö unit of the same size. Because connecting the cooker hood to a ventilation/air heating unit is no longer a rec-ommended solution, the cooker hood is replaced and a dedicated duct is run through the ceiling and roof.

The Pingvin Kotilämpö unit is of the same size as the old Valmet air heating unit. It has energy-efficient direct current fans and an efficient heat recovery unit. Instead of a cross-flow heat exchanger used in the old units, Pingvin Kotilämpö features a rotating heat exchanger similar to those used in the Enervent ventilation units, providing an annual efficiency of over 70%.

The Pingvin Kotilämpö unit is equipped with the MD control system – again, the tech-nology used in the Enervent ventilation units. For more information about the control system, see section 7.2.



10.2 Partial heating with the Enervent MDX systemMDX is an air-source heat pump integrated into ventilation after-heating and after-cool-ing. The Enervent units’ integrated heat pump acts as an energy-efficient heating source. During the heating season, the rotating heat exchanger recovers up to 80% of the heat energy present in the extract air. This energy is transferred back via the ventila-tion ducts to heat the indoor air.

The MDX system is a combination of a rotating heat exchanger, the most efficient me-chanical heat-recovery method, and a heat pump with a DC-powered compressor. The need for additional heating in the wintertime is covered with an efficient heat pump. In normal buildings, other heating sources are also required. MDX works well with all heating sources and heating systems.

When the temperature is below freezing, the MDX system recovers moisture from the extract air with its rotating heat exchanger. The system is suitable for both new build-ings and renovation projects. The most energy-efficient solution is to use this system in a low-energy or passive house.

All MDX systems feature DC- compressors, and they use R410A refrigerant for maximum efficiency. MDX can be fitted to most Enervent’s ventilation unit frames. An evaporator coil is installed inside the ventilation unit or in the supply air duct, and an outdoor air unit is installed outside the building.

10.3 Partial heating with Enervent HP eAirThe Enervent HP eAir unit has an integrated extract-air-source heat pump. Combined with a rotating heat exchanger, the extract-air-source heat pump can recover all heat energy present in the exhaust air and return it for space heating.

The Enervent HP system is suitable for both new buildings and renovation projects. Because the system does not have a separate outdoor unit, it is also suitable for sites where the installation of outdoor units is restricted by regulations on façades.

A combination unit saves on installation costs. The air is distributed evenly because no separate supply air units are required. The system features two separate systems for heat recovery. It can be used with all heating systems.

The best level of energy efficiency can be ensured by including a room-specific ther-mostatic temperature control in the system design. The ventilation unit pre-heats the supply air and the room-specific temperature control is provided by a terminal device equipped with a heating element. A supply air terminal with heating can increase the temperature of the pre-heated supply air from +35...+38 °C up to a maximum of +45 °C at an air flow rate of 10 l/s, according to the heat demand of the room.


10.4 Dimensioning and selecting the unit for air heating

The process of designing an air heating system is started by determining the supply and extract air flow rates required for normal ventilation for each room.

If air heating is the main heating system, a supply air terminal device should be located in each room to be heated (excluding wet rooms and toilets).

If supply air is to be delivered to wet rooms, its flow rate must be notably lower than the extract air flow rate. This ensures that air is not transferred from the wet rooms to oc-cupied spaces. A supply air vent can also be located in the laundry room, provided that its air flow rate is lower than the extract air flow rate. This rate can include the extract air flow rates of adjacent spaces equipped with extract air vents only.

The dwelling should be designed so that there is slight underpressure. A suitable under-pressure level is achieved if the extract air flow rate is 3 to 5% higher than the supply air flow rate. The more airtight the house is, the lower the level of underpressure is needed. In the renovation projects of leaky houses, the extract air flow rate can be 10% higher.

An example of air heating dimensioningRoom-specific heating energy demands (conduction + infiltration + make-up air + ven-tilation) are calculated according to Section D5. The total demand must also include the output of the after-heating coil. It is calculated on the basis of the supply air flow rate in normal ventilation, and the supply air temperature value to be used in the calculation is the value downstream from the rotating heat exchanger.

An example of calculating the design energy demandThe design energy demand in the example is about 2.0 kW. In other words, this is the amount of heat energy this passive house consumes when the outdoor temperature is –10 °C. The design outdoor temperature is –10 °C because at that temperature the heat pump can still cover the majority of the house’s energy demand. In Helsinki, tempera-tures below –10 °C prevail on only about 5% of the days of the year, which is about 18 days. The surface area of the example house is about 100 m2. The ventilation unit is an outdoor-air-source heat pump (MDX).

Full or partial load?At this stage a decision can be made on whether the heating power of the air heating system is designed for a full or partial load. An air heating system covers 75% of the annual heating energy demand (Section D5), provided that the nominal power of an air heating system equipped with an outdoor-air-source heat pump is 50% of the heating energy demand of the heating system for the space in question. Preliminary air flow rates can be selected on the basis of the energy demand, and the ventilation unit on the basis of its output curve.


When designing systems that are connected to an outdoor-air-source heat pump, it must be noted that the outdoor unit is switched off at temperatures below –20 °C. The units have an additional electric heater as standard for extremely low temperatures.

In this example, the calculated total heating energy demand at a temperature of –10 °C is 2.0 kW. Because air heating heats only the spaces air is delivered to, it is reasonable to study the heating energy demand of these spaces. In this example, the heating energy demand of the spaces equipped with a supply air terminal device is 1.75 kW. The required output for ventilation after-heating is taken into account.

The power value of 1.75 kW is used for selecting the unit, if the system is to be dimen-sioned for a full load. In this example, the system will be dimensioned for a partial load, which is 50% of the design energy demand. Therefore, the resulting nominal power is 2.0 kW * 0.5 = 1.0 kW.

In this example, the required part-load power is 1.0 kW and the supply air flow for heating is 1...3 l/s/m2; the dimensioning process is started on the basis of these precon-ditions. The Enervent Energy Optimizer dimensioning software is used for selecting a suitable unit. The desired temperature for nominal power (in this case, –10 °C) is entered in the Optimizer’s extra input values section, and the estimated air flow rate for deliv-ering additional heat in the building is entered in the air flow field. The results section shows how much the unit generates heat at each value specified above.

The Pandion MDX-E has good performance values at the air flow rate of 100 l/s, and the heat pump generates 2.3 kW of heat at a temperature of –20 °C (downstream of heat recovery compared with the supply air temperature). The unit generates excess heat that heats the spaces as follows

Øi = ρi x Cpi x qiv x ΔT = 1 x 1.2 x 100 x (31.4 – 21) = 1.25 kW

The total air flow rates in the example house during heating are 1.5 times higher than the normal air flow rates.

According to the Energy Optimizer software, the supply air temperature is +31.4 °C when the outdoor temperature is –10 °C and the indoor temperature is +21 °C.

Then, the temperature difference (ΔT) is 31.4 – 21 °C = 10.4 °C.

Based on the temperature difference, the heating power (excess heat) delivered into the rooms is calculated using the following equation:

Øi = ρi x Cpi x qiv x ΔT

Q = ρi x Cpi x qv x ∆Tρi = air density, 1 kg/m3

Cpi = specific heat capacity of air, 1.2 kJ/kgCqv = air flow, l/s∆T = temperature difference (22 °C – 13 °C)

Calculation of heat pump’s nominal power

The nominal power of a heat pump is specified at the outdoor temperature of +7 °C.

The temperature immediately downstream of the heat recov-ery unit is about +18 °C, and immediately downstream of the heat pump’s evaporator coil about +33 °C. Exact temperature values can be calculated with the Energy Optimizer software.


The air flow rates are determined for the rooms based on the energy demand so that the required minimum air flow rates are met in every room. The air flow rates can be determined on the basis of the room energy demands, for example, so that the total air flow rate is multiplied by the ratio of the room energy demand and total energy demand.

Example:Bedroom energy demand: 350 WThe required air flow rate is

qv= Q/ρi x Cpi x ΔTð 350 W / 1.2 x 1 x 10.4 = 28 l/s

In some cases, the calculated air flow rate may be lower than the required minimum air flow rate. If this is the case, the flow rates of such rooms must be increased to the minimum level, and the flow rates of other rooms must be decreased when designing the final air flow rates, so that the desired total air flow rate is achieved.

If necessary, the energy demand calculations can be updated when the design air flow rates are decided. Increasing the air flow rates will always have some impact on the energy demand and therefore also on the E-value. The design energy demand with the updated air flow rates (supply +100 l/s and extract –103 l/s) is 2.0 kW.

At this stage, the total air flow rate or flow rates of some spaces can be decreased or increased, provided that the minimum requirements set for the outdoor air flow specified in Section D2 are met. Similarly, room-specific heating energy demand can be decreased, for example, by structural modifications. The choices are revised when the desired modifications are made.

Even though the heating power rates for some spaces were slightly higher than the corresponding energy demands, it can be assumed that the heat will transfer to other spaces with air.

Impact on the E-valueThe heating energy demand of the building is calculated normally. The required after-heating output must also be included in the heating energy demand if the unit is used also for heating the supply air. According to Section D3 of the National Building Code of Finland, the heating energy generated by air-air heat pumps that are working permanently as part of a ventilation or heating system can be taken into account in full.

According to Section D5 of the National Building Code of Finland (later referred to as Section D5), the share of heating energy generated by an air-air heat pump of the heat-ing energy demand of spaces (QHP/Q heating, spaces, DHW) is calculated as a function of relative heat output (ØHPn / Øspace) in different weather zones. The heat pump’s nominal power (ØHPn) is given at operating point T

outdoor/T

indoor +7/20 °C. The SPF value

is 2.8, unless otherwise specified.

0,0

0,5

1,0

1,5

2,0

2,5

3,0

3,5

4,0

30 40 50 60 70 80 90 100 110 120 130 140 150

10°C

15°C

20°C

Pandion MDX heating


The heat pump’s nominal power can be determined from the pump’s output curve at the outdoor temperature point of +7 °C, or it can be calculated with the Energy Optim-izer software. The relative heat energy shares for air-air heat pumps are provided in Table 6.10 in Section D5.

Selecting the terminal devicesWhen designing an air heating/cooling system, special attention must be paid to the selection of the supply air terminal devices. Throw patterns, noise and potential draft discomfort in both cooling and heating modes must be taken into account when se-lecting the supply air terminal devices. It is recommended to select a supply air terminal device with good mixing performance. Mixing terminal devices ensure constant room temperature and reduce the risk of draft discomfort. If the terminal device mixes the supply air efficiently into the room air, the supply air can be blown to the room from the top section of the wall or from the ceiling.

The extract and circulation air terminal devices should be such that fouling does not have a notable impact on the air flow rates. They should also be easy to clean.

The operation of terminal devices must be ensured in the entire air flow range (heating, cooling and normal ventilation). The maximum air flow rates and terminal devices must be selected so that noise and flow problems are also avoided in cooling mode. When the air flow rate is doubled, the pressure difference is quadrupled and the sound level is increased.

Ductwork designThe selection of ducts and duct components must always be based on the maximum air flow rates, which are determined by the heating or cooling energy demand.

The ductwork should be as short as possible and easy to maintain. The air velocity should not exceed 3 m/s in order to avoid excessive pressure loss and high sound levels.

Silencers must always be fitted to the supply and extract air ducts. The silencers should be selected carefully, taking account of the fan noise in the ductwork and the maximum permissible sound levels in rooms. The sound levels must also be taken into account in dimensioning the ductwork and selecting the terminal devices. The requirements concerning sound insulation between rooms must also be considered in design. A door undercut impairs the sound insulation properties of the door. A sound insulation level that corresponds to a closed door can be achieved with a transfer air device equipped with a silencer.

Duct insulationThe ventilation ducts must be insulated so that condensation cannot form on the inte-rior or exterior surfaces of the duct in any circumstances. Moreover, excessive heating or cooling of air must not take place in the ductwork. Insulation is dimensioned case by case based on the ductwork location and temperatures. When dimensioning the


insulation, it must be noted that the air temperature in the exhaust air duct may be well below zero. The exhaust air temperature at different outdoor temperature conditions can be calculated with the Enervent Optimizer dimensioning software. The insulation manufacturers’ software can also be used for determining insulation thickness levels.

The insulation of the supply air duct from the ventilation unit to the terminal device must be designed and implemented so that the temperature of the air flowing in the duct does not change by more than 1 °C.

The insulation of the extract air duct from the terminal device to the ventilation unit to terminal device must be designed and implemented so that the temperature of the air flowing in the duct does not change by more than 1 °C.

Examples of ventilation duct insulationOutdoor air duct (fresh air duct)

Cold space: 100-mm board, mat or half-section insulation (in addition to these, possible blown-in insulation).

Warm/half-warm space*):

Alternative 1: 80-mm insulation with vapor-proof outer layer

Alternative 2: 20-mm foam rubber insulation on the duct and 50-mm insulation with vapor-proof outer layer. The insulation must prevent condensation of vapor on the exterior surface of the duct and excessive heating of air in summer.

Exhaust air duct

Cold space: 100-mm board, mat or half-section insulation

Warm/half-warm space:

Alternative 1: 80-mm insulation with vapor-proof outer layer

Alternative 2: 20-mm foam rubber insulation on the duct and 50-mm insulation with vapor-proof outer layer.

The insulation must prevent condensation of vapor on the exterior and interior surfaces of the duct.

* A half-warm space means, for example, a false ceiling, intermediate floor or channel.


ENERVENT CHG – VENTILATION PRE-HEATING AND PRE-COOLING


The CHG coil (Cooling/Heating Geo) is a lamella coil that is installed into the ventilation unit’s fresh air duct. It is connected either directly to a separate ground circuit, or to the ground circuit of a ground-source heat pump through a fluid heat exchanger. Depend-ing on its use, it can act both as a pre-cooling and pre-heating coil in the ventilation system. It is an excellent choice as a support system for any heating system.

The ground circuit fluid heats the coil in winter and cools it in summer. The CHG circuit fluid is usually a water-glycol mix (such as Dowcal 10) or an ethanol solution.

The CHG coil helps in saving energy because it significantly reduces the consumption of heating and cooling energy in the ventilation system by utilizing free energy instead of purchased energy. It evens out the extremes in outdoor temperatures during winter and summer, thus enabling lower heating and cooling power ratings for the ventila-tion unit. Thanks to the CHG coil, there is no need to design the ventilation unit for the extreme temperatures, which saves on both energy and investment costs.

The CHG coil improves the reliability of the ventilation system by reducing the risk of malfunction in extreme temperatures when there is extremely cold or hot weather. Moreover, it significantly reduces the need to defrost the ventilation unit and therefore also the demand for defrosting energy.

If the ventilation unit does not have any other cooling equipment, the CHG coil enables some kind of cooling of the supply air in summer.

The CHG coil has an air filter (class G3 coarse filter) that extends the life of the unit’s fresh air filter to some extent.

Issues to be noted in design and installationVentilation pre-cooling can be implemented on all sites that have a mechanical supply and extract air ventilation system and where installing a ground circuit is possible. The type of heating system used in the house is of no consequence. Therefore, the system can be installed in an older building too.

The designer is responsible for dimensioning a suitable collection circuit and the necessary system components, such as a circulation pump, shutoff valves, pressure vessels, etc., on the basis of system data (pressure levels and flows). For houses with a ground-source heating system, the designer also selects a suitable fluid heat exchanger between a ground circuit and a coil circuit.

The CHG coil can be connected to a dedicated collection circuit that is usually made of plastic piping with a diameter of 40 mm. The collection circuit is dug in the ground at a depth of about 1 m and installed in loops such that the distance between the pipes is at least 1.5 m. The total length of the collection circuit should be 150 to 200 m. The local ground frost depth must be verified to determine the proper installation depth for the collection circuit.

It is useful to perform the installation of the collection circuit simultaneously with a garden renovation, since soil needs to be dug from a large area. The more moisture the ground contains, the higher the pre-heating efficiency is. Ground with a high water


Technical informationCoil range and delivery contents

CHG package CHG 200 CHG 250 CHG 400

Coil type VEAB CWK 200-3-2.5-L/R VEAB CWK 250-3-2.5-L/R VEAB CWK 400-3-2.5-L/R

Product code for CHG package L: K930040501V (left-handed)R: K930040501 (right-handed)

L: K930040502V (left-handed)R: K930040502 (right-handed)

L: K930040503V (left-handed)R: K930040503 (right-handed)

Suitable for Enervent units (NOTE: Larger coils can be used also for smaller units)

Plaza, Pingvin, Pingvin XL , Pandion, LTR-2, LTR-3

Pelican, LTR-6 Pegasos, LTR-7

Coil's duct connection size Ø 200 mm Ø 250 mm Ø 400 mm

Coil's outer dimensions and weight when dry/fluid-filled

L 395 x H 330 x D 415 mm, 10/11 kg

L 395 x H 405 x D 491 mm, 12/13.5 kg

L 450 x H 529 x D 715 mm, 22/24.7 kg

Filter (plain filter) 1 filter, filtering class G3, 379 x 296 x 13 mmA spare filter set includes 6 filter pieces (no grate)

1 filter, filtering class G3, 454 x 372 x 13 mmA spare filter set includes 6 filter pieces (no grate)

1 filter, filtering class G3, 679 x 472 x 13 mmA spare filter set includes 6 filter pieces (no grate)

Fluid pipe connectionsCondensate water connection (vacuum)

22 mm½ ”, must be equipped with a water seal



Valve and actuator Belimo R313 (R3015-4-S1), 3-way, Kvs 4, DN 15TR24-SR, 0-10V

Belimo R317 (R3020-4-S2), 3-way, Kvs 4, DN 20HRYD24-SR, 0-10V

Belimo R322 (R3025-6P3-S2), 3-way, Kvs 6.3, DN 25HRYD24-SR, 0-10V

Additional outdoor air temper-ature sensor for Enervent MD devices

1 sensor, 5 m 1 sensor, 5 m 1 sensor, 5 m

content retains heat more efficiently, which makes moist, clayey soil the best soil type for energy efficiency, while dry, sandy soil is the most inefficient.

The CHG coil can also be connected to the ground circuit of a ground-source heat pump. The coil needs to have a dedicated fluid circuit, which is separated from the fluid circuit of the energy well with a fluid heat exchanger. Therefore, a different fluid circulates in the ground circuit from that in the coil circuit. The coil circuit fluid is usually a water-glycol mix (such as Dowcal 10) or an ethanol solution. The antifreeze content of the fluid circuit fluid is determined on the basis of the lowest anticipated temperatures for the site. The minimum glycol content in southern Finland is 35...40%, and in northern Finland 45...50%. The CHG coil must always be equipped with a separate pump. The pump must be dimensioned so that it can circulate the fluid properly. The dimensioning of the pump is affected by the length of the piping and the pressure losses of the coil and valves.

The dimensioning is best done with calculation and dimensioning software. In case rules of thumb are desired, the following can be used: The pressure loss for a 40-mm collector piping is 0.05 kPa/m, and the pressure loss of the coil and valve is 25 kPa. For example, with a 200-meter collector piping, the pressure loss used for dimensioning the pump is 200 m x 0.05 kPa/m = 10 kPa + 25 kPa = 35 kPa: the lift height of the pump is dimensioned so that the optimal point is achieved when h = 3.5 meters.

The CHG coil and related piping must always be insulated, including the outdoor air duct section between the pre-cooling coil and ventilation unit. Also, the supply air ducts of the ventilation system must be insulated.

Because the cooling coil removes a lot of moisture from the air in summer, a drain con-nection and water seal are mandatory. The water seal must be located in a warm space.

The coil must be installed in a horizontal position, and it should be tilted slightly for con-densate removal. The coils are manufactured in both left- and right-handed models. The maintenance door must open to the side. Easy access to the coil must also be ensured for filter replacement and maintenance tasks.

Automated controlThe CHG coil is controlled using the MD control system. The function is activated with the eAir control panel. The CHG coil function has its own setup parameters in the eAir control panel. The CHG function requires the installation of an additional temperature sensor in the outdoor aid duct upstream of the CHG coil.

The control system starts the CHG circuit circulation pump and controls the coil’s 3-way valve to its full capacity if the outdoor temperature is lower than the pre-set value (facto-ry setting +5 °C). The control system stops the function when the outdoor temperature exceeds the pre-set limit value (factory setting 1 °C).

From a horizontal ground circuit or energy well

The majority of new ground-source heat pump systems take their energy from an energy well. The energy well is more expen-sive but often more functional solution for the energy demand of the CHG coil, especially for old buildings. The energy well can be drilled in a yard without causing a significant damage. However, a horizontal ground circuit is a good solution, especially if the yard is likely to undergo a major renovation.

The collection circuit is usually made of a 40-mm collector pipe in which non-freezing fluid, usually an ethanol solution, circulates. The circuit is dug in the ground and in-stalled as deep as possible, but at least to a depth of 1 to 2 meters. A total of 150 to 200 meters of pipe is needed for the collection circuit. The pipe is installed in loops so that the distance between the pipes is at least 1.5 m. Because ground with a high water content retains heat more efficiently, moist, clayey ground is the best soil type for this purpose.

Page 1 of 1

8.9.2014http://www.gtk.fi/export/sites/fi/geologia/kuvat/geoenergia_1.jpg

Ground surface temperatures in Finland. Figure: Geological Survey of Finland (GTK).Source: GTK, Niina Leppäharju


Air temperature Ground surface temperature


PITFALLS OF DESIGN

After getting this far in reading this manual, every reader must have noticed that designing the optimal indoor climate is far from a simple task – although this may have been obvious to most of you beforehand. But this does not mean that the task is impossible. A professional designer can achieve excellent results every time by focusing on the project thoroughly and carefully.

However, people make mistakes and sometimes problems emerge. In this section we discuss some problems that should be taken seriously.

12.1 Make-up air

Problem: I cannot light a fire in the fireplace. The ventilation unit freezes during frosty weather.Suitable make-up air solutions must be arranged for cooker hoods, wood-burning sauna stoves and other fireplaces. Especially in energy-efficient houses, a chimney equipped with a make-up air channel should be used. They provide the fireplace with a sufficient amount of combustion air directly from outside at all times. This solution ensures that the use of the fireplace does not disturb the operation of the ventilation unit, and the energy efficiency of the building is also improved.

If the fireplace does not have a dedicated make-up air channel, it draws the air from the easiest available source. In an airtight building, the make-up air is taken through the ventilation ducts and ventilation unit. A rotating heat exchanger requires a sufficient amount of warm extract air in relation to the cold outdoor air coming to the unit in order to operate properly during frosty weather. Otherwise, the ventilation unit may freeze.

12.2 Sound levels in the occupied space

Problem: The noise generated by the ventilation system is annoying and keeps us awake.Section D2 provides the guideline values for maximum sound levels resulting from the ventilation system. These guideline values may not be exceeded, even during boosting.

Sound travels through door undercuts from one room to another unless this is prevent-ed, for example, with acoustic doors. Disturbing noise levels can also be experienced due to structural-borne noise. The transmission of this noise must be prevented by careful mounting of the ventilation unit and ductwork.

The ventilation unit should not be installed in the vicinity of a bedroom.

PITFALLS OF DESIGN

PITFALLS OF DESIGN

12.3 Reserve for higher flow rates

Problem: Suddenly there is not enough air when the grandparents moved in downstairs.When designing the ventilation system, the changes in the purpose of use and in the number of residents during the entire life span of the building must be taken into ac-count. The ducts must be sized to provide a reserve for increasing the air flow rates. This will avoid a situation where the air flow rates should be increased but it is practically impossible to implement due to, for example, overly high sound levels at the higher velocity levels.

12.4 Humidity control

Problem: Water runs down windows after having a sauna. All steam is extracted immediately from the sauna room.The temporary changes in the indoor air humidity level are not sufficiently taken into account in the guideline values for air flow rates provided in the National Building Code of Finland. Having a sauna, showering and bathing generate temporary but extremely high moisture loads that the ventilation system should be able to remove in a controlled manner. A system designed to the guideline values may not be sufficient to cope with the situation. The best way is to design the ventilation system so that it automatically boosts the air flow rate to control the moisture load.

If the ventilation unit must be installed into a room with high humidity, condensate wa-ter management must be carefully considered. If water condenses on a tile wall, it will surely condensate on the metal housing of the ventilation unit as well. The unit should never be placed inside or above a cabinet or shelving that has poor moisture tolerance. Installation in a false ceiling in a bathroom or laundry room, for example, should be avoided.

Designing a ventilation system for a sauna is an art itself. A fixed extract air vent must always be located below the benches. If an extract air vent is desired in the ceiling of the sauna room, it must be closable. If the extract air vent in the ceiling is kept closed during bathing, the moist steam rising from the stove does not go directly to the ven-tilation duct and further to the ventilation unit. This keeps the steam inside the sauna room longer and the ventilation system is provided with better conditions to cope with the high temporary moisture loads. Moreover, the flowing air extracted below the benches keeps the lower bench and the lower section of the wall paneling dryer.

PITFALLS OF DESIGN

12.5 Space for ventilation unit maintenance

Problem: Performing maintenance tasks on the unit is difficult. I tend to postpone the replacement of the filter.The best location for the ventilation unit is usually a separate mechanical room. The ventilation unit filters must be replaced regularly, and the room must allow adequate space for performing any required maintenance task as easily as possible. It must be ensured already at the design stage that there is easy access to the ventilation unit and that its maintenance door can be fully opened.

12.6 Impact of filter fouling on the air flow rates

Problem: The indoor air quality declines towards the end of the filter life.According to the National Building Code of Finland, the building shall be designed and constructed as an entity in such a way that a healthy, safe and comfortable indoor climate can be achieved in the occupied zone under all normal weather conditions and operational situations. These requirements must also be met at the end of the filter life. Therefore, it is not sufficient that the guideline values for air flow rates are met only with new, clean filters. The designed air flow rates must have sufficient margin beyond the guideline values to ensure that the healthy, safe and comfortable indoor climate is also achieved with somewhat dirty filters.

12.7 Condensate water drain from inside the unit

Problem: Where does that water come from?

The smaller ventilation units must always be equipped with a condensate water drain and water seal.

The Piccolo On ventilation unit can be mounted above the kitchen range. The condi-tions are quite optimal for the formation of condensation, and a suitable, hidden route must be designed for the installation of the condensate pipe and water seal.

PITFALLS OF DESIGN

12.8 Avoiding overpressure

Problem: There is not enough air for everybody, I cannot light a fire in the fireplace and my mother-in-law cannot open the doors. Excessive pressure difference is one of the main reasons for problems associated with an incorrectly designed, implemented or used mechanical ventilation system.

A normal Finnish one-story detached house is a good candidate for pressure problems. Typically, the house is rectangular and the wet rooms and kitchen are located at one end of the house and the bedrooms at the other end. This means that the extract air ducts are at one end and the supply air ducts at the other. The air in the middle does not move.

In order to avoid overpressure, the supply and extract air flow rates should be designed to be sufficiently balanced at both ends of the house.

In multi-story buildings, the bedrooms are typically located on the second floor and a toilet (and sometimes a walk-in closet) is located in the immediate vicinity. This creates a risk of having a notably higher amount of supply air than extract air in the second floor, resulting in overpressure. This overpressure is increased further by the tendency for air to rise.

In ventilation design, it must be ensured that the upper floors are designed to have negative pressure. This can be done by adding an extract air duct in the second floor hallway or by including both supply and extract air ducts in all or some of the second floor bedrooms, for example. This will also ensure sufficient bedroom sound insulation when the need for door undercut is eliminated.

12.9 Last-minute changes

Problem: Cooling is included in the system but it does not work.

Sometimes a busy design schedule leads to unfortunate mistakes. Let’s image a scenar-io in which the customer has made a clear statement that he does not want cooling in his dwelling. However, cooling is included in the ventilation system next door. When the installation is about to begin or has started, the customer changes his mind. Now cooling is absolutely necessary. Dimensioning of the air flow rates and ducts for the new specifications is forgotten due to the busy schedule or some other reason.

PITFALLS OF DESIGN

12.10 Cooperation with other designers

Problem: The system just does not work like it should.

At best, designing the building services engineering solutions for a house is a joint effort between a number of skilled professionals, resulting in an accurate modeling that will help installation.

The plans for the ventilation unit’s external connections must be drawn up in coop-eration with the relevant designers responsible for each special plan (for example, electrical, automation, water and sewer system designers).

Smooth interaction of external sensors, actuators, pumps, dampers and pipes is essen-tial for the operation and easy installation of the ventilation system.

PITFALLS OF DESIGN

EXAMPLE CASES – ENERVENT VENTILATION SOLUTIONS IN VARIOUS PROJECTS


13.1 Wood-framed, brick-lined detached house with plastered exterior wall, Helsinki

Residents The Kuusinens, a family of four

Year of construction 2006

Ventilation renovation 2013

Floor area 170 m2

Living area 145 m2

Heating system direct electric heating, air-source heat pump

Original ventilation unit

ventilation unit with a cross-flow heat exchanger, efficiency of heat recovery about 40%

New solution Enervent Pingvin MDE with the eAir control panel

Quieter and more efficient with a new ventilation unitReplacing the old ventilation unit with a new one improved both energy efficiency and comfort.

The father of the family is a sales manager who has lived in Eastern Helsinki for almost his entire life. His wife, born and bred in the center of Helsinki, was tempted to move to Vartiokylä due to the peaceful living environment and the possibility to run the family’s everyday life smoothly.

This wood-framed, brick-lined detached house with plastered exterior walls by Finndo-mo was built in 2006, and it has proven to be a good choice in every respect.

- This has a ventilated floor structure. Vartiokylä, a neighborhood of Helsinki, is built on an old marshland area. If the floor structure does not work, moisture damage can de-velop in a very short period of time. When we were looking for a home, we visited way too many houses that were relatively new but already suffered from moisture damage, Kuusinen explains. They do not need to worry about underfloor moisture damage because a mechanical ventilation system is arranged with a roof ventilator.

Modern and spaciousThe first floor includes a lounge area that extends up to the second floor, a modern kitchen, sauna and a laundry room. The bedrooms are located on the second floor.

The light-filled lounge area features large panoramic windows and a charming open fireplace which – to be honest – is not very useful in terms of heating. An air-source heat pump has already been purchased to reduce heating costs and to enable cooling and dehumidification of the indoor air in summer. In winter 2013, the family had had enough of the old and noisy ventilation unit that also had very poor control properties.


- Its efficiency was so low that I, being a thrifty person, kept the unit at the first setting (in a four-step control system). It had no automatic control functions. Every time we had a sauna, we had to remember to set the unit to a higher setting and then back down after the excess moisture was removed. And it was very loud, the father of the family reminisces.

In December, the unit was replaced with an Enervent Pingvin MDE unit with the eAir controller. Except for cleaning, the ventilation ductwork required no additional work. – The ventilation ductwork of a detached house needs to be cleaned at a minimum of every ten years. The ducts in our house were relatively clean but in any case it was reasonable to do the work in connection with the replacement of the unit.

Nothing was done to the terminal devices either. In fact, a new supply air valve should have been installed in the lounge area because the original vent cannot distribute the supply air evenly throughout the entire space. But a new terminal device would also have required a new duct, which would have been a very laborious job and would have needed work inside the intermediate floor.

The air flow rates were adjusted after the installation of the Enervent Pingvinin unit.

A definite improvementThe improvement on the old system became evident very quickly.

- Now we can keep the ventilation rate at the level to which it was designed in the first place. The sound level is noticeably lower.

Even though no certain conclusions on the annual amount of energy to be saved due to the new unit cannot be drawn only after a few months of use, it is already obvious that the new unit is more energy efficient than the old one.

- In summer, we use the air-source heat pump for cooling the indoor air. Because the Pingvin unit can also recover the cooling energy, it is no longer wasted.

Automation in the control system adds to comfort levels. The humidity boost function increases the ventilation rate automatically after we have a sauna because the system includes a humidity sensor as standard.

- The unit can remove excess moisture from the indoor air in about five minutes, the father of the family says – and sounds very pleased.

Enervent Pingvin MDE costs about 5,000 euros installed. The family has calculated that the savings in the heating electricity costs will be about 650 euros per year. In this case, the payback period would be about nine years.

- But even more important is the increased comfort the new ventilation unit has brought about, he points out.

The unit fits nicely above the cabinet in the laundry room.

Pingvin MDE improved ventilation.

Good indoor air quality can be enjoyed in the spacious living room in all conditions.

13.2 New detached house made of concrete blocks, Pukkila

Builder and residents Antti Ikonen and his family

Year of construction 2012–2015

Floor area 240 m2

Volume about 900 m3

Heating system hybrid heating system

Energy class B

HVAC design Aki Mikkelson

Solution Enervent Pegasos HP Aqua ventilation unit with a rotating heat exchanger, integrated extract-air-source heat pump and dehumidification function

Required heating power 9.5 kW

Ventilation cooling power 3.5 kW

Ventilation cooling power with dehumidification

8.7 kW

Design air flow (cooling) 290 l/s

Straightforward hybrid solutionA professional selects an uncomplicated and highly reliable ventilation and heating system for his home.

The municipality of Askola, located in Eastern Uusimaa, delivers its operations relating to building supervision and environmental protection in cooperation with the municipali-ties of Pornainen, Pukkila and Myrskylä. Being the acting head of this division, Antti Iko-nen has seen a vast number of structural and building services engineering solutions in various new detached house projects in the area over the years. As a professional in the construction industry, he is also familiar with the latest options and understands quite well what objectives should be included when building as energy-efficient a detached house as possible in a cost-effective manner – and what objectives are not yet quite reasonable.

- For the time being, there is not enough know-how about passive houses, let alone on zero-energy houses, to make them reasonable options, especially for a self-builder. Even for a professional, they require in-depth expertise, experience and special attention, he points out.

Durable and cost-effectiveLike many Finnish men, Antti Ikonen wanted to build a home for his family himself. But because a busy working life and a growing family set certain limits on the time availa-ble, decisions on certain basic factors had to be made at the beginning of the project.


Aki Mikkselson and Antti Ikonen in the future living room.

Antti Ikonen


- It takes time when you are building a house yourself with your father. I have done the building mostly during the summers, and I do not yet dare to promise that we can move to our new home by Christmas 2014. Therefore, the materials and construction methods had to allow for a long building time.

A masonry house is a durable and safe solution. The insulated block structure produc-es walls that need only appropriate surfacing. Hollow-core slabs are used above the basement floor.

The energy class of the building will be B, a low-energy class. Passive construction was not possible with the selected type of EPS blocks. The structures are designed to be as airtight and as well-insulated as possible. The roof was insulated with polyurethane to ensure the best possible thermal insulation capacity and airtightness, and to maximize space.

The Ikonen family will have a second child in fall 2014, and they have also considered getting another husky. The total area of the house is about 300 m2 over one story, which is a sensible solution for a family home. The basement will include a mechanical room with extra space for hobbies.

Focus on comfortThe lounge area has large windows because the amount of natural light was some-thing Antti Ikonen did not want to compromise on. The energy-efficient windows have anti-fog coating and also a sun control coating to prevent the room from becoming overheated in summer.

- Still, cooling the indoor air in one way or another had to be taken into account in the ventilation system design, Antti Ikonen remarks.

The builder considered the heating and ventilation solution for his house in cooper-ation with HVAC designer Aki Mikkelson. Various options were discussed in terms of investment and operating costs, and the final decision was made with the emphasis on comfort.

In a family with several children and pets, underfloor heating is a major comfort factor. The consumption of domestic hot water is also high. In addition to a Pegasos HP Aqua unit, water in the Ikonens’ house is also heated by a heat-storing fireplace with water circulation. Heat is stored in a 750-liter Akvaterm accumulator tank.

Everything else is provided by a single unit, Enervent Pegasos HP Aqua, which also in-cludes the dehumidification function. The unit is a ventilation unit equipped with both mechanical heat recovery system (rotating heat exchanger) and an integrated extract-air-source heat pump. Therefore, its heat recovery capacity is notably higher than that of the traditional heat recovery solutions. Excess heat from the heat pump is stored in the accumulator tank from where it can be used for heating.

Efficient in every respect

On hot summer days, the main reason for a feeling of discomfort is not the temperature itself but the high humidity level. If the excessive moisture is removed from the indoor air, the air needs to be cooled only slightly to make it feel pleasant. Due to the dehu-midifying operation, the extract-air-source heat pump of the Enervent Pegasos HP Aqua unit cools the supply air to about +7...+10 °C. Then the after-heating coil heats the air to +17...+19 °C, and the air is blown in at this temperature. Even during the most humid heatwave periods, all rooms have a constant and comfortable indoor air quality.

An energy-efficient ventilation system takes account of changes in conditions both indoors and out. The Enervent Pegasos HP Aqua unit is controlled by an integrated carbon dioxide sensor and a humidity sensor. The ventilation rate is boosted by a signal from the humidity sensor after taking a shower, for example.

Aki Mikkelson says that designing a ventilation system for an airtight, energy-efficient building requires thorough research of the various options and careful calculations. - The air flow rates must be designed to the correct level, and the cooling function makes this more challenging. We also studied a demand-controlled, room-specific ven-tilation system as one option for this project but it was discarded due to higher costs. This made balancing the ventilation system challenging because the system balanced for the design condition had to be balanced also for lower air flow rates, he explains.

In a demand-controlled ventilation system, the air flow rates are controlled with room-specific flow rate controllers based on occupancy. This means that the system sets the ventilation rate in an empty bedroom to a lower setting with the flow rate controller, while the ventilation rate in other rooms remains unchanged. If this control system is not included in the design but cooling must be included, the air flow rates must be adjusted to the high flow rates of the cooling mode, but it must also be ensured that the ventilation rate is sufficient at low air flow rates in the rooms at the end of the ductwork.

If the dimensioning is correct, the indoor air quality is good and the ventilation system works correctly in all conditions.


Pegasos HP Aqua qv = 290 l/s Design conditions: Winter, –10 °C

+3 °C

Warm water

Cold water

+22 °C

–7 °C

–10 °C

+22 °CEXTRACT

OUTDOOR

EXH

AU

ST

SUP-PLY

+/– 0 °C

+23 °C

+29 °C

Fan


Filter

Aqua

Evaporator coil

Water coil

Compressor

Q = heating power, si = air density [kg/m3), q

vi = air flow [l/s], ∆ T = excess heat [°C], c

pi = specific heat capacity of air [kJ/

kg °C]

Q = si x cpi x qvi x ∆T

= 1.2 x 1.0 x 290 l/s x (29 – 22) °C = 2,436 W

Temperature of the supply air blown into the building: +22 °C. Amount of energy

transferred to the accumulator tank: 2,436 W.


13.3 Old renovated country house, Askola

Residents A couple visited regularly by their adult children

Decade of construction 1790

Renovation 1820, 1931, 1960, 1989, 2007–2008

Surface area about 350 m2 over two floors

Volume 850 m3

HVAC design Pohjois-Espoon LVI/Marko Räsänen

Heating and ventilation solution

Enervent Pelican eco PRO greenair HP and Enervent Pelican eco EDX-E

Required heating power 10 kW at –10 °C (additional heat for conditions below –10 °C is provided by fireplaces or direct electrical heating)

Ventilation cooling power

9.5 kW

Ventilation cooling power with dehumidi-fication

9.5 kW

Design air flow 450 l/s

Comfort of a five-star hotel room in a historic homeEven a house over 200 years of age can be renovated to an energy-efficient condition and improve the quality of indoor climate to the highest level – without compromis-ing on style.

After spending 16 years abroad, this family moved to Askola and bought a farmhouse, which was built in the late 1700s and extended a couple of times. The family familiar-ized themselves with the possibilities and limitations related to renovation projects for improving the energy efficiency of old houses.

- Trying to make an old house meet the passive house level is not reasonable because its airtightness cannot be improved to the level of a new building. But low-energy levels can surely be met with the help of modern insulation materials and energy-ef-ficient windows, and by utilizing an efficient heat recovery system and heat pumps. When adding thermal insulation layers and sealing up structures, it must absolutely be ensured that these actions do not impair the quality of indoor climate. The correct po-sitioning and careful installation of the vapor barrier must also be ensured, this country gentleman emphasizes.

The old house had natural ventilation that did not work. Heating this two-story, very ca-pacious house in winter was expensive, and due to a sunny hillside location, the indoor temperatures reached the levels of a poor sauna in summer.

The renovation was designed to improve the energy efficiency and comfort of living so that the features that worked well were retained and utilized without compromising the interior style.

Thermal insulation was improved with the most reasonable and ecological method by using cellulose insulation, and the entire roof structure was insulated with polyurethane to save space. The windows of the second floor bedrooms were replaced with new, more energy-efficient windows. The downstairs windows had already been renovated previously.

Constant temperature and high indoor air qualityIn terms of comfort of living, the introduction of the mechanical ventilation system was the most essential change.

- Having lived abroad, we were used to a well-functioning mechanical ventilation that can also dehumidify and cool the supply air on hot summer days. That was something we did not want to compromise on.

Marko Räsänen, a highly experienced but now unfortunately deceased HVAC designer, accepted the challenge with the confidence gained from over 500 single-family house design projects. But the solution that was finally selected was a pilot project even for him.

The objective for the ventilation design was a constant indoor temperature of 22 °C and draft-free ventilation regardless of the time of year. Moreover, independent control of a number of rooms was also required. The residents also wanted to keep the old but fully functional tiled stoves operational to provide additional heat. Because the installation of ventilation ducts was inevitable, the most reasonable heat distribution method was air heating – which was rare to find in single-family houses at that time.

When the renovation was planned, the now-adult children lived at home. The con-sumption of domestic hot water was not very high even for a family of four, and now in a household of two adults it is downright minimal.

- A ground-source or air/water heat pump can be a good solution for a large family. But for us it would have been unnecessary, the owner of the house points out.

A separate system for each wingThe house has two wings, and a separate system was designed for each. If necessary, different indoor air temperatures can be selected for the south and west wings. The air is changed once every hour in one wing, and – thanks to the air recirculation function – at a standard rate of once every two hours in the other wing. One-third of the air is taken from outside, the rest is circulation air.

In one wing, ventilation is provided by an Enervent Pelican eco PRO greenair HP, which is a ventilation, air heating and cooling system that is based on a rotating heat exchang-er and an integrated extract-air-source heat pump without an outdoor unit. In the other wing, the same tasks are carried out by an Enervent Pelican eco EDX-E equipped with a Mitsubishi outdoor unit. The outdoor unit provides additional power for cooling on


The owner of the house in the hall. Notice the terminal devices on the ceiling.

Outdoor unit.


the hottest days and for heating at the higher range of sub-zero temperatures. More additional heat can be generated by using the tiled stoves, and the electric heating elements step in at extremely low temperatures.

- But they are not required very often, the owner remarks.

- In total, the two heat pumps provide over 10 kW of heating power with a combined power consumption of less than 4 kW, and they are sufficient for temperatures below –10 °C.

Electric heating is used for additional heating. Electric heaters are located below large windows and set to +17...+18 °C. These prevent uncomfortable cold radiation when sitting in front of the windows during harsh winter frosts.

Plenty of powerThe annual efficiency of heat recovery of the Enervent Pelican eco PRO greenair HP is over 90%, and the corresponding value of the Enervent Pelican eco EDX-E is over 70%. The heat pump capacity is not included in the efficiency of the EDX unit. In order to have an air heating and cooling system in a house of this size, the air flow rates had to be higher than what a Pelican unit can deliver. This was why an Enervent Energy MixBox circulation air unit was included in the system. If necessary, it can quadruple the air flow rate, even if the basic ventilation rate is kept constant.

When designing the heating, cooling and ventilation system, the main focus was on energy efficiency. This has proven to be successful: the owner says that at an outdoor temperature of –34 °C, the exhaust air temperature of the greenair HP unit was –28.5 °C with an indoor temperature of +22 °C.

Cooling is also very energy efficient because cold air is recovered as well – or actually warm air is sealed out.

- Even at high outdoor temperatures of +28 °C, the air-source heat pump runs only occasionally, says the pleased owner.

The rotating heat exchangers of the units transfer the heat and moisture from the sauna to the dry indoor air.

- The humidification of indoor air is needed in winter because otherwise the parquet floors and wall paneling in the old house would suffer, the owner explains.

The system does not have a CO2 control function because it is not required if the air

flow rates are this high.

Unnoticeable ductwork installationMany people are hesitant about getting a mechanical ventilation system in an old house because they think that the ductwork installation would be troublesome. In

Climecon’s terminal device on the kitchen ceiling is like a decoration.

The ductwork required enclosing at one location only.

most houses built after the mid-1900s, the ducts can be enclosed so that they should not upset interior designers. If the house is much older, the ducts should be concealed completely, which requires the renewal of interior surfaces. The owner says that he was surprised to see how well Lindab’s pre-insulated ducts could be hidden in a house built in the 1700s. For example, there was just enough space available to install ducts in the slanted ceiling upstairs. The ducts were larger than normal – ø 200 mm, and ø 160 mm for rooms – because they were dimensioned for the higher-than-normal air flow rate required by cooling.

- Sufficiently large ducts also contribute to low ventilation noise levels.

In the kitchen, one cabinet had to be pulled 250 mm away from the wall. The ducts going up to the second floor were concealed with a clever structural solution in the staircase. In fact, the ductwork only needed to be enclosed at one location, and it could have been easily missed if the owner had not pointed it out.

Climecon’s terminal devices, which resemble a flower, blend surprisingly well into the ceiling. A supply air terminal in one bedroom was equipped with a 500-W electric heat-ing element to enable increasing the supply air temperature as quickly as possible.

Naturally, the ducts are carefully insulated to prevent any problems with condensation – and to eliminate efficiency loss.

- Cooling efficiency decreases very rapidly if uninsulated ducts are used, such as under a hot roof.

The actual units were located out of sight in the cellar below the kitchen.

There is always room for improvementThe owner is very pleased with the operation of both systems. However, he is going to improve energy efficiency even further. In the summer, a 2-kW array of panels will be installed on the roof to provide free solar power for the ventilation cooling system and freezers.

- If I was going to plan a similar renovation project now, I would include a humidi-ty-based control system in the ventilation system and add dedicated combustion air ducts for the tiled stoves, the owner concludes.


Pelican eco EDX-E qv = 160 l/s Design conditions: Summer, +24 °C, RH 60%, AH 11 g/kg

+22 °C

+23.5 °C+24 °C

+13 °CEXTRACT

OUTDOOR

EXH

AU

ST

SUP-PLY

+22.5 °C

Separate outdoor unit

Hot air out

Refrigerant pipes

Electric heating coil


Filter

Evaporator coil

Fan


13.4 renZero energy renovation project, ‘veteran house’, Luumäki

Owner The Salopelto family


renZero energy renovation 2014

Surface area 182 m2

Heating energy consumption be-fore the renovation

150 kWh/m2

Heat distribution via the ventilation system

Ventilation unit Enervent Pandion MD-CHG

Heating system also includes ground-source heat pump, solar collectors, energy tank

Target The E-value requirement for energy perfor-mance class A 83 – 0.02 x 181.7 m2 = 79.37 kWh/m2per year

Efficient energy renovation in a single-family house Energy renovation in the 65-year old home of the Salopelto family started in 2013 and was completed in spring 2014. This is a significant pilot project, in which a wood-framed house is being renovated into an energy class A building. The house represents the traditional Finnish ‘veteran house’, developed during the reconstruction period after World War 2 as a self-build house for soldiers returning from the Front. Its ventilation is provided by the Enervent Pandion MD-CHG, and the heat distribution system is ventila-tion heating.

In Finland, there are about a million old detached houses, and experts think that at least those built pre-1980 should be renovated to improve their energy efficiency.

This 1.5-story veteran house, built in 1948, is located in Luumäki, near the city of Lap-peenranta in south-east Finland, and it was almost in its original condition before the energy renovation started in 2013. The changes made over the years were minor – even the floorboards are original. Only some of the windows were replaced, and supple-mental frames were added on to others. The wood-framed and wood-clad house had a metal roof. Sawdust was used as the insulation material in the building envelope.

Long-time homeLike in all veteran houses, the first floor contains the kitchen, living room and one other room. A cold porch at the entrance offers a pleasant extra space in summer. Upstairs features two bedrooms, a sauna and bathroom facilities. The residents have been very pleased with the highly functional floor plan and timeless architecture of their home.

This house is the birthplace of Seppo Salopelto, a building engineer and vocational school teacher. He has lived in the house for almost his entire life and, with his wife, raised their three children who have since moved away.

In addition to energy savings, Mr. and Mrs. Salopelto wanted to carry out a thorough renovation to improve the level of comfort in the old house. Being a professional in the construction industry, Salopelto acts as the project supervisor and uses it as a base material for his Master’s thesis.

As energy efficient as a new buildingThe Salopeltos’ home was selected as a pilot project for the renZero project. The project is funded by the Finnish Funding Agency for Technology and Innovation (Tekes) and it aims to develop a cost-effective energy renovation concept for single-family hous-es. Launched in 2011, the project seeks a functional solution to improve the energy efficiency of Finnish and Swedish single-family houses built between the 1940s and the 1970s.

The target of the pilot project was set high: to convert a leaky old building to an energy class A building whose air leakage rate would be even lower than what is required for a new building. It is likely to be close to the energy performance of nearly zero-energy buildings. The fact that the residents of the house would continue to live in the house throughout the renovation project made the project even more challenging.

Thorough energy renovationThe exterior walls of the building were completely renovated. The roofing, windows and doors were replaced, and the building envelope was clad with ventilated renovation elements developed specifically for this purpose by Paroc.

It is obvious that an airtight and well-insulated building envelope is not sufficient to make a house a nearly zero-energy building. In addition to reducing the energy con-sumption, the share of renewable energy must be increased. In the Salopeltos’ house this was implemented by utilizing ground-source heat and solar energy.

After the renovation, heat in the house is distributed conveniently via the ventilation system. This prevented extensive installation work required by a radiator network or water-based underfloor heating. A mechanical supply and extract air ventilation system was needed for energy efficiency, but also to improve the indoor air quality. Therefore, the Enervent Pandion MD-CHG ventilation unit takes care of ventilation and recovers heat from the extract air, and it also cools the indoor air in summer. When the supply air is cooled down, the excess heat energy removed from the outdoor air is transferred into the energy well.

Ground-source energy and the heat energy provided by the solar collectors are used for heating both domestic hot water and supply air. The outdoor air ducts of the ventilation system contain dedicated water-based heating coils for the first and second floor. The flow in the water coils is controlled with motorized valves according to the heating requirement, using the room temperature control method.The working fluid of the heat pump circulates in the CHG coil installed in the outdoor air duct of the Enervent Pandion MD-CHG ventilation unit. The coil works as an outdoor air pre-heater in winter and a pre-cooler in summer.


The house prior to the renovation.


Maximum airtightness

The project can already be deemed successful by calculations but only time will tell how energy efficient and comfortable the Salopeltos’ renovated home is in practice. In any case, it is now anything but drafty and leaky. Based on measurements from February 2014, the difference between the new and old values is significant, although there still are some leaks. The leaks are found in the basement and floor structure, which was excluded from the scope of the renovation, and also partly at the joint between the porch roof and the old wall, which could not be fully accessed for sealing without damaging the structures.

Before the renovation, the air leakage rate (n50) was about 9 1/h and now it is 3.1 1/h. The official requirement for new buildings is 4.0 1/h. The improvement in air permea-bility was 65%. According to Section D5, a single-family house has a good level of air permeability if the air leakage rate is below 3 1/h, and the average level is achieved with the rates from 3 to 5 1/h. The improvement was very good for an old house, even though the passive house level was not achieved.

Extensive monitoringNext to the old main distribution board of the house, a new board version has been erected that enables detailed monitoring of the consumption and production of heat energy, for example. Four monitoring devices were installed in the mechanical room to measure the con-sumption of domestic hot water and the energy production of the ground-source heat pump and solar collectors for VTT Technical Research Centre of Finland. All devices are connected in series and can be read remotely via the 3G network.

Ensto Enervent remotely monitors both the ventilation performance and carbon dioxide levels in the bedroom and living room. During the period from March to summer, the indoor temperature has remained near the set value. On a few hot days in the spring, the room temperature did not exceed +25 °C, and the CHG coil cooled the supply air up to 12 °C.

The renZero development project is coordinated by Paroc and funded by Tekes, and in addition to Ensto Enervent, partners include Arkkitehtuuritoimisto Kimmo Lylykangas, Metsäwood, Oilon, Puuinfo, Skaala, and VTT. The other pilot project house was also built in the 1940s and it is located in Sweden, near the center of Stockholm.

The final report of the project will be published at the end of 2014.

27.3.2014 Paroc renZERO, Talo Salopelto, Luumäki 3

+/-

+/-

+

+

eAir

AL24A1T

24VAC

Pandion MDW-CHG

Upstairs

1st floor

Supply 230VAC, 50Hz, 10A Earthed wall socket

Wall socket type overvoltage protector

TE20

TE10

TE45

TL45

TE01

TE11

VLP45

TL46

SV46

SV45

VLP46

TL50

SV50

PU50

CHG FG1

FG39

M1

M39

13.5 Siwa Uudenmaankatu grocery store, Hyvinkää

Developer Jari Niskanen, Suomen Lähikauppa Oy


Surface area 350 m2

Heating system district heating

Old ventilation technology supply air unit, extract with a roof ventilator

Ventilation renovation 2013

HVAC design Sweco Talotekniikka Oy/design director Jussi Ainamo, design manager Ismo Marin

Solution Enervent Pallas HP Aqua with dehumidification function

Design air flow (cooling) 2.0 l/m2 in the sales room

All-in-one packageIn this grocery store, Enervent Pallas HP Aqua provides ventilation and heat recov-ery, as well as the cooling and dehumidification of indoor air. The annual efficiency of heat recovery is over 90%.

Located on Uudenmaankatu in the center of Hyvinkää, Siwa grocery store is honored to be a pilot project. It is the first store of the Suomen Lähikauppa grocery chain in which doors were retrofitted to refrigerators. In conjunction with this, the ventilation system of the store was also renovated.

It has been shown that retrofitting doors is one of the most effective ways of affecting the energy consumption of a refrigeration system in a grocery store. It is estimated that it reduces the cooling energy demand to almost one-third of the original demand.

Dehumidification needs attentionHowever, merely retrofitting doors on the existing refrigeration equipment in an old store would lead to other problems, because the open refrigeration equipment has contributed to the dehumidification and cooling of the indoor air on hot summer days.

In most old stores, like in this Siwa store built in 1979, the supply air was only taken directly from outside and heated. Moisture can also enter the store from the door when customers walk in and out and when the store is ventilated.

Without any indoor dehumidification, the conditions are poor. On hot summer days, moisture condenses on cold (usually about +12...+13 °C) refrigeration equipment doors and hides the products behind fogged glasses. At worst, water can drip onto the floor and cause a slipping hazard. If the humidity level remains high for a longer period of time, it will also impair the quality of dry products in the store.



In this Siwa store, the increased moisture load on the indoor air due to the door retro-fitting project was tackled by renovating the ventilation system. The old supply air unit was located on the store premises, and one old roof ventilator extracted the air.

- It was a pretty normal solution in the stores of its time, says Ismo Marin, a design manager for Sweco Talotekniikka Oy, the company responsible for the design of the HVAC renovation.

- We also had to find a more energy-efficient and functional ventilation solution, Jari Niskanen continues.

- The old ventilation system could not provide good indoor conditions even before retrofitting the doors to the refrigeration equipment in all climatic conditions.

A versatile solution in one packageMarin says that for Siwa Uudenmaankatu, the Enervent Pallas HP Aqua unit with dehu-midification was an excellent solution, because it enables the recovery of the maximum amount of heat from the indoor air. The unit is equipped with both a mechanical heat recovery system (rotating heat exchanger) and an integrated extract-air-source heat pump. Therefore, its heat recovery capacity is notably higher than that of the traditional heat recovery solutions.

– At times, the temperature of the exhaust air has been below zero, Design Director Jussi Ainamo confirms.

More energy savings are gained by the possibility to run the ventilation in full recir-culation mode during the nighttime. Because a CO

2 control system is included in the

ventilation system, the amount of fresh air is always demand-controlled to maximize energy savings.

The recovered heat is stored in a 500-liter tank. From there, the energy is used for heat-ing the supply air.

During the very hottest days of summer, the heat pump carries out the necessary dehu-midification of the supply air by cooling it down to +12...+14 °C. Then the dehumidified air is heated with the after-heating coil to a pleasant temperature of +18...+20 °C by using the condensing heat stored in the tank.

The new ventilation system required some new ducts to be fitted. The existing exhaust ducts were left operational but routed via the extract-air-source heat pump to the Pallas HP Aqua unit. It was important to have a ventilation system that provides constant con-ditions for the entire store area. Moreover, the system had to be as quiet as possible – a requirement that had to be taken into account when sizing the ducts.

- The guys had some serious challenges in fitting the required ducts on and between these low-height structures and the old glulam post-and-beam frame, says the shop-keeper, praising the skills of the installers. The renovation project had to be implemented without closing the shop, and the plan succeeded.

Heat is stored in a 500-liter tank.

The store is the Siwa store chain’s pilot project for retrofitting doors to refrigeration equipment.

Construction Management Director Jari Niskanen says that the quality of indoor climate is now excellent for the staff.

Because the project for retrofitting doors to refrigerators and the ventilation renovation were completed in fall 2013, we have to wait till summer 2014 to see how the supply air dehumidification really works.

- I trust it will work well, Niskanen believes.

So far, the shopkeeper, staff and customers alike have been very satisfied with the new ventilation.

- The store is kept at a constant temperature at all times, and the indoor air quality is also notably better. And the ventilation system is very quiet, Niskanen says and sounds very pleased.


The accumulator tank must be designed so that enough energy can be transferred and stored in the tank for the time the facility is not in use (such as nights).

Pallas HP Aqua KI W qv = 450 l/s Design conditions: Fall, winter, spring, air recirculation function

Warm water

Cold water

+20 °C +28 °CEXTRACT SUPPLY

FanFilter

Dampers closed

Aqua


Evaporator coil

Water coil

Circulation air damper

open

Compressor


13.6 Industrial building and office premises, Porvoo

Company Metallityöliike Tom Nyberg Ky/Anders Nyberg


Contractor Best-Hall Oy

Surface area about 1,500 m2

Volume 8,380 m3

HVAC design Ab Ingenjörsbyrå Jörgen Holm Insinööritoimisto Oy / Jörgen Holm

Heating and ventilation solution

4 pcs Pallas HP Aqua KI with dehumidification function and 1 pc Pegasos HP Aqua with dehumidification function

Additional heating district heating

Contractor Ilmastointikulma Oy

Plumbing contractor LVI-Center Auhtola Oy

Electricity/Automation EK-Automatic

Required heating power 53 kW

Ventilation cooling power 27 kW

Design air flow (cooling) 2,790 l/s

Ideal indoor environmental conditions for a production facility

The ventilation, heating and cooling of the different spaces are handled in a cost-effec-tive and convenient way with dedicated units.

Metallityöliike Tom Nyberg Ky, a mechanical engineering company based in Porvoo, invested in a modern production building at the right time, in the middle of a recession. The coffee roastery of Robert Paulig Oy operated as a tenant in the company’s old hall and needed more space.

- They wanted to include our machine shop for their use. A recession period means lower demand in the engineering industry, so there was time to act as a developer. When the growth starts, there will also be a lack of space also here in Porvoo, Anders Nyberg says.

Flexible possibilitiesWhen a company is looking for production and office facilities, location, good indoor con-ditions and modifiability are key considerations. The operational environment is changing rapidly and the premises must be able to meet the changing needs as easily as possible. In addition to structural solutions that enable division and extension of premises, modifia-bility must also be taken into account in the building services engineering systems.

Just this kind of modern, modifiable production building was developed by Metal-lityöliike Tom Nyberg Ky in Tolkkinen in 2013. The company moved its production operations to the new building in early 2014. Now the company can rent out a large hall, either as one entity or conveniently split into two separate spaces, and a modern, light-filled office space over two stories.

Founded in 1964 and managed by Anders Nyberg, Metallityöliike Tom Nyberg Ky is a family-owned company now in its second generation. Being typical lifestyle entrepre-neurs, his parents are not yet fully retired. And the environment to continue could not be better: everything in the new machine shop is designed to work perfectly and the conditions are excellent.

The company’s plot and its production buildings are located right by the Gulf of Finland in Tolkkinen, Porvoo. The view of the sea from the office windows at the shore side of the new production building is something that would cost an arm and a leg in a residential building.

Metallityöliike Tom Nyberg Ky acquired the industrial building, built in 1971, with the plot ten years ago. The building is connected to a district heating network. District heat-ing was one of the options considered for the new production building.

- It would have been the least expensive option in terms of the investment costs, but its operating costs were somewhat unpredictable, Nyberg points out.

A ground-source heating system was also considered, but drilling the energy wells is a quite expensive and – in a high-radon area – a risky solution. The collector pipes could have also been laid on the sea bed, but Nyberg thought that this was not a safe option due to busy ship traffic.

Cooling is an important featureNyberg wanted a functional, demand-controlled ventilation solution that would enable both indoor air cooling and dehumidification.

- Today, air-source heat pumps are also used for heating modern, energy-efficient pro-duction buildings. They provide heat in the heating season and, if necessary, cool the indoor air in summer. But because work performed in the machine shop also generates a lot of waste heat in winter, we needed a more versatile solution than just air-source heat pumps, Nyberg explains.

In spring 2014, cooling was required when the outdoor temperature has been as low as +8 °C.

The solution designed by HVAC designer Jörgen Holm provides all spaces with optimal conditions in the most flexible, energy-efficient and cost-effective way possible. The production facilities can be divided into three sections. Each section should have a dedicated ventilation, heating and cooling system, because the needs can vary a lot depending on the nature of the operations. The needs in the office and social facilities with an area of about 250 m2 are also different. A different heat distribution system is also used. In the production facilities, air heating is used as the heat distribution system, whereas a water-based underfloor heating is used in the office and social facilities for comfort. The social facilities also have a shower room for staff. The demand for domestic hot water in the production facilities is low.


Aqua in the spacious and bright hall.

Nyberg is very satisfied with the investment.


Climecon’s terminal device on the hall ceiling delivers high-quality supply air evenly.

Pallas HP Aqua KI W qv = 450 l/s Design conditions: Winter, –10 °C

+3 °C

Warm water

Cold water

+20 °C

–6 °C

–10 °C

+18 °CEXTRACT

OUT-DOOR

EXH

AUST SUPPLY

+/– 0 °C

+22 °C

+25 °CCirculation air damper

Compressor

Fan

Evaporator coil

Water coil is off, heat is gen-erated by the heat pump


Filter

Damp-ers

Temperature of the supply air blown into the building: +18 °C. Amount

of energy transferred to the accumulator tank: 3,780 W.

Q = si x cpi x qvi x ∆T = 1.2 x 1.0 x 450 l/s x 7 °C = 3,780 W

Aqua

Q = heating power, si = air density [kg/m3), q

vi = air flow [l/s], ∆ T = excess heat [°C], c

pi = specific heat capacity of air [kJ/kg °C]

Professional design

The ventilation, heating and cooling solution of the building consists of one Enervent Pegasos HP Aqua unit and four Enervent Pallas HP Aqua KI units – all of these units are equipped with dehumidification function.

- They are an excellent choice because they contain everything needed in one package, Nyberg remarks.

The ventilation, heating and cooling solution of the building is implemented in sections. The heat recovered from each section is transferred via the EnergyBUS to an energy bank, a 5,000-liter Akvaterm accumulator tank located in the mechanical room. From the accumulator, heat is utilized according to need: for the underfloor heating system and domestic hot water system in the office floor, for heating the supply air with the heating coils in the ventilation units, and for reheating the supply air that is dehumidified by cooling on hot summer days.

Electric heating elements are used to provide additional heat at the very lowest tempera-tures in winter. District heating is also available as a backup system for extremely long cold spells.

The system has already proved to be very energy-efficient over a period of six months: the amount of heating energy consumed for the new hall is only one-sixth (6,500 kWh) of the amount of energy required for heating the old hall.

Designing an air heating and cooling system for a production facility requires both exper-tise and experience of the designer.

- Excellent indoor climate conditions and good indoor air quality can be ensured by dimensioning the system so that sufficient cooling and heating power is ensured. The air flow rates must be dimensioned higher for air cooling. Sufficient capacity cannot be ensured at the minimum level specified in the National Building Code of Finland, empha-sizes HVAC designer Jörgen Holm.

Staircase-specific ventilation unit

2 X Pallas HP GLTO• 550 l/s standard rating• 715 l/s boosted

The southern end of the building remains pleasantly cool when the excess heat generated by the sun is transferred via the EnergyBUS to the other side of the building.

13.7 EnergyBUS in an apartment buildingThe internal energy distribution system of the building levels out the temperature differences between apartments

In apartment buildings, the need for heating, cooling and indoor air dehumidification varies between different spaces, even during the same season. The sunny side may require cooling in early spring, while the heating season is still far from ending on the shady side of the building. Leveling out such temperature differences is one of the key factors for comfort and energy efficiency in today's construction projects. In practice, the building is divided into a number of sections and ventilation is designed separately for each section. Excess energy is recovered and transferred via the EnergyBUS to an accumulator tank shared by the entire building. This energy, already purchased and supplied to the building from outside, is then delivered from the tank to cooler sections of the building. In addition to the excess heat, cooling energy can also be recovered by the air-source heat pumps and then used for cooling other spaces.

Grocery store provides energy for residentsA good example of utilizing the EnergyBUS is an apartment building with a grocery store at street level. Normally, the ventilation system for the store and its refrigeration equipment is designed and implemented as a separate entity, and another system is designed for the apartments. This traditional method can result in a situation in which the store causes significant additional costs for the housing company and its residents. The EnergyBUS enables the recovery of excess heat generated by the store's equip-ment. Thanks to this solution, the warm water used by the residents can be heated with energy recovered from the building for the major part of the year.


Fresh air/outdoor air

Shower/DHW

Fresh air/outdoor air

The store has its own EnergyBUS unit

StoreApartment

Apartment

Apartment

Apartment

Summer: The supply air is cool and dry. Excess heat is used for heating domestic hot water.

Winter: The supply air is warm, ventilation heat loss is minimal. Excess heat from the heat pump is used for heating domestic hot water.

Exhaust airfrom the apartment

Extract airfrom the apartment

Supply airto the apart-ment

Exhaust airfrom business premises

FROM PILOT PROJECTS TO STANDARD CONSTRUCTION PRACTICES – PASSIVE AND ZERO-ENERGY HOUSES WILL SOON BECOME MAINSTREAM

Professionals in the construction industry around the world are striving to find solutions to slow down the rate of global average temperature increases. Buildings have a very high energy savings potential. In Europe, buildings account for about 40% of total en-ergy consumption. In Finland, the energy consumed in buildings account for one-third of total greenhouse gas emissions, which is about 22 million tons of carbon dioxide per year.

Therefore, improving the energy efficiency of both new buildings and the existing building stock is one of the simplest and easiest ways of reducing energy consumption and slowing down climate change. An energy-efficient building is also better than an inefficient building in terms of the comfort of living and operating costs, provided that it is constructed correctly.

Improving the energy efficiency of construction is truly a win-win opportunity. It also benefits the national economy by increasing the value of the building stock. It creates new markets for energy-efficient solutions, building materials and systems, and building services engineering solutions. We have been at the front line in introducing practices for energy-efficient construction and required energy efficiency in construction and renovation in our building code. Therefore, we have the upper hand in developing solu-tions, turning them into products and marketing them domestically and globally.

If a method provides excellent results in the harsh Finnish climate, how well it can work elsewhere?

14.1 Clear-cut methodsNaturally, the greenest energy is energy that doesn’t need to be consumed at all.

The methods for reducing heating energy costs of buildings are relatively simple to implement.

» The building must have a well-insulated and airtight envelope and a ventilation unit whose annual efficiency of heat recovery is as high as possible.

» The electrical equipment used in the building must be as energy-efficient as possi-ble.

» Solar energy must be utilized to the highest degree possible.

» Energy consumption must be monitored by measuring.

» The source of heating energy is selected on the basis of environmental friendliness, energy efficiency and economic efficiency.



14.2 Gathering expertiseEnergy-efficient construction is not a new thing in Finland. The first time energy effi-ciency was significantly improved in the construction of new buildings was back in the aftermath of the 1970s oil crisis. Structures were made more airtight, thermal insulation was improved and triple-glazed windows were introduced. Some test projects for low-energy construction were carried out in the 1980s.

The Finnish construction and construction product industry has carried out some relatively ambitious pilot projects in recent years. These projects prove that passive and computational zero-energy buildings can be built using normal materials and tradition-al methods. It requires careful design as well as precise construction and installation work, but when compared with the standard-level construction, the additional costs are surprisingly low.

After piloting, the principles of highly energy-efficient construction should be applied to ordinary construction more extensively. The ambitious target is for all new buildings to be nearly zero-energy by 2020. The EU requires that as of the beginning of 2019, new buildings occupied and owned by public authorities are nearly zero-energy buildings, and this requirement is extended to apply all new buildings as of the beginning of 2021.

In order to truly reduce the amount of energy consumed for heating the buildings and the amount of carbon dioxide emissions, the energy efficiency of the existing buildings must also be significantly improved. This is not an easy task because there should be productized energy renovation methods available for all types of buildings to make the renovation projects profitable. Renovation projects that are separately tailored to each building are very laborious.

Energy renovation pilot projects have already yielded good results in apartment build-ings and single-family houses, for example. An energy renovation project of a traditional Finnish veteran house can be found in Chapter 13.

14.3 From a standard building to energy-plus construction

Regardless of the target level of energy efficiency for a new building, there are some principles that apply in every case. An airtight and well-insulated building envelope is the single most important factor. Efficient heat recovery in the ventilation system prevents the waste of expensive energy that has already been purchased.

The position of the building in the plot can have a significant impact on the building’s energy efficiency, but an optimal position is not always possible. On the other hand, the importance of the source of energy decreases as the amount of energy consumed decreases.

People tend to forget that even a standard building built according to the valid building code is highly energy efficient. It complies with the minimum requirements of the building and energy performance regulations. The regulations will change over time, and when the energy efficiency requirements for new buildings change next time, a standard building from 2014 will not necessary comply with all requirements of the new regulations.

When talking about energy efficiency in construction, there tends to be a number of terms, the meaning of which is not generally agreed upon. Moreover, the requirements set for passive buildings, for example, vary by country, and they also change along with new information and technological development.

A low-energy house uses 50% less energy than a standard building that complies with the requirements of the building regulations. This can be achieved by investing in the thermal resistance and airtightness of the building envelope and in the ventilation system’s heat recovery. Low-energy houses can be built using standard existing tech-nology. The annual energy demand is 50...60 kWh/m². This definition is quite established in Europe.

A passive house uses only 25% of the energy used by a standard building. No separate heating sources are necessarily required for heating the building because people, household appliances and lighting provides sufficient heat. A passive house requires a high-quality ventilation unit that can utilize the majority of heat energy contained in the exhaust air and use this energy to heat the supply air. The annual efficiency should be at least 70%. The need for purchased energy varies by location: consumption in Central Europe is 15 kWh/m² and in Northern Europe not more than 30 kWh/m². VTT’s calcula-tions show that the average heating energy demand for a passive house is 20, 25 and 30 kWh/m² in southern, central and northern Finland, respectively. The primary energy demand is 130 to 140 kWh/m².

Based on the above, the expected heat energy demand of a passive house is one-fourth that of a standard building.

A zero-energy house generates the same amount of energy as it consumes on an annual basis. In practice, this is always a matter of calculation, because both consump-tion and production can vary a lot – especially in the Finnish climate. In other words, a zero-energy house must produce at least the same amount of renewable energy as its consumption of non-renewable energy. The structures must be extremely airtight and well-insulated. All building services engineering solutions must be highly energy efficient. The building must also generate the majority of electricity used for other purposes than heating.

An energy-plus house can produce more energy than it uses and sell some excess energy to a national network or other buildings.

Key figures for passive houses

Heating energy demand 20 to 30 kWh/m².

Maximum air leakage rate (n50) 0.6 1/h.

U-value of the doors and windows 0.40 and 0.80 W/m²K respectively.

Minimum annual efficiency of the ventilation unit’s heat recovery 70%.



14.4 Increasing the popularity of passive houses

A passive house is no longer a rarity, even in Finland. In Germany, passive houses have already been built for a decade, resulting in about 10,000 houses. Sweden also outnum-bers Finland in the number of passive houses.

Today, there should be no reason why a passive house should not be built. Experience shows that it can be achieved with any type of structure and any kind of construction material. There are no limitations in terms of architecture either. An efficient ventilation unit that recovers excess heat generated by people, household appliances, electron-ic devices and lighting, can keep the indoor temperature constant year round. The amount of heat generated by one person equals to a 100-W light bulb, and a flat screen TV can heat a room of up to 40...60 square meters.

When building a passive house, special attention is paid to thermal insulation, airtight-ness, and solutions with higher-than-average energy efficiency. On the other hand, savings are gained because traditional massive heating systems with the related heat distribution system is not required.

Air heating is an energy-efficient and comfortable heating method for a passive house. The supply air can be heated with a heating coil located in the ventilation unit, or the unit can be connected to room-specific electric heaters with a thermostatic control.

An external heat source is required for the coldest months of the year and for heating domestic hot water. There are plenty of options, and they can also be combined into various hybrid solutions. Heat-storing fireplaces, fireplaces with water circulation, and all kinds of heat pumps and solar systems are environmentally friendly options.

We Finns love to have a home with warm floors, and underfloor heating can be used as an additional heating method in passive houses. However, it must be designed and dimensioned carefully because the required heating power is low.

The building costs of a passive house are on average 5 to 10% higher than a standard building. It is estimated that the payback period for detached houses is six years.

14.5 Ensto Enervent’s solutions for passive and zero-energy houses

A passive house provides low operating costs and an optimal indoor climate. The ener-gy-efficient ventilation and heating solutions ensure that the indoor air temperature is constant, there is no draft discomfort, and the air is pure and fresh to breathe. A good ventilation system ensures clean indoor air, which is one of the prerequisites for healthy

living and is also highlighted as a key factor in terms of comfort in airtight passive houses.

This is where the modern energy-efficient houses differ from the houses built after the energy crisis at the end of the 1970s – the houses of that era could be as airtight as a bottle, yet without any proper ventilation system. Passive and zero-energy houses have a good and healthy indoor climate. The changes in the indoor air temperature are low. Because there is no cold draft, it does not need to be compensated with excessive heating.

One of the cornerstones of energy-efficient construction is a mechanical ventilation system that is equipped with efficient heat recovery. Air is taken indoors in a controlled manner mechanically and on the basis of actual need, and make-up air cannot infiltrate into the building through poorly sealed structures.

Demand-controlled ventilation means that the residents do not need to pay any attention to the ventilation system unless they want to. Thanks to modern building automation, the ventilation system can be set to operate at a lower rate automatically when nobody is at home. This saves energy. Because the system includes sensors that measure the indoor air humidity and carbon dioxide levels, there will be plenty of fresh air when family and friends gather to celebrate.

The system allows room-specific temperature control because the rooms are equipped with thermostats.

Ensto Enervent has been involved in developing solutions for passive houses from the very beginning. Thanks to the high annual efficiency of heat recovery, its ventilation units are excellent for projects where especially high energy efficiency is required. The ventilation, heat recovery, heating, cooling, and dehumidification solutions are integrated into one single unit to make the design and installation work easier, and they can easily be connected to other building services engineering systems, such as heat pumps and building automation systems.

Ensto Enervent’s ventilation units have been used in a number of passive house projects demonstrated at the Finnish Housing Fair in recent years. In ‘TV-talo’, a project that was built for the 2009 Housing Fair in Valkeakoski and was followed in a Finnish homebuild-ing and renovation show, the ventilation was provided by the Enervent Pegasos, and the Enervent Pandion eco EDE was selected for ‘Passiivitalo Pekkarinen’ in Kuopio 2010. In Tampere 2012, a passive house project ‘Ruislaine’ was equipped with the Enervent Pingvin eco EDE, and the ‘Tervakukka’ project has the Enervent Pelican HP and, for wet rooms, Enervent Pingvin eco EDE.



14.6 Other development projects in energy-efficient construction

Developing energy-efficient construction further requires close cooperation between all parties involved in the construction industry. The structures and all building services engineering systems must work seamlessly together to ensure the designed, energy-ef-ficient operation and the promised level of comfort of living. Therefore, Ensto Enervent will participate in a number of interesting projects in the next few years. The renZero project coordinated by Paroc is presented in Chapter 13.

14.7 EEMontti – improving the energy efficiency of electrically heated houses

Ensto is a member of Green Net Finland – a cleantech business network that brings together the expertise and resources of Finnish cleantech companies, scientific and educational institutions and public authorities, and promotes the know-how of the industry. The association coordinated an EEMontti project as a competition for service providers in order to reduce the heating costs of electrically heated houses by half. The project was implemented in 2011–2012, and the purpose was to find energy renovation solutions for about 500,000 electrically heated detached houses in Finland.

During the EEMontti competition, energy renovations were implemented in detached houses that were built in the 1960s, 1970s and 2000s and equipped with direct electric heating. A working group from Helsinki Metropolia University of Applied Sciences documented the results of the renovations during the six-month follow-up period. The main objective of the competition was to cut the heating energy consumption in half in the four target houses. The energy consumption included the energy purchased for the ventilation system and space and domestic hot water heating. The target houses from different eras represent about 500,000 Finnish single-family houses that do not have a water-based heating system. This house type is considered to be very difficult to renovate.

The EEMontti competition showed that there can be more than one way to implement a successful energy renovation. The various options should be studied carefully without immediately falling into the one that is the easiest implement or the most affordable to purchase.

The ventilation renovation of the house from the 1970s was implemented in a one-story detached house whose annual energy consumption was about 31,000 kWh. The house was equipped with a heat-storing fireplace, an air-source heat pump and mechanical extract air ventilation. The make-up air infiltrated uncontrollably into the building through the structures.


In connection with the renovation, the house was fitted with an Enervent LTR-3 eco EDX-E ventilation unit with an integrated air-source heat pump. This way, the unit can be used for heating and also for cooling the indoor air. An electric after-heating coil ensures proper supply air temperature, even at the very lowest temperatures in winter. The old electric heaters were replaced with new ones. An Ensto eGuard energy monitor was also installed to measure the total energy consumption of the house.

The total cost of the renovation was about 19,000 euros, from which the tax credit for domestic costs, 4,000 euros, was subtracted. During the follow-up period, the energy consumption was reduced by about 30% compared with the previous situation. The annual savings amounted to about 1000 euros. It was estimated that the renovation increased the market value of the house by 10,000 euros. What’s more, the indoor air quality was significantly improved.

The payback period for the investment is 12.5 years.

14.8 HP4NZEB – reaching nearly zero-energy levels with the help of heat pumps

Green Net Finland’s HP4NZEB project (Heat Pump Concepts for Nearly Zero Energy Buildings) focuses on finding energy-efficient and cost-effective ways to use heat pumps in constructing nearly zero-energy buildings – the role of heat pumps is out-lined for both new buildings and renovation projects. The project seeks concepts specif-ically for Finnish circumstances. The outlined concepts will be simulated for heating and cooling energy demand and electricity consumption, and their economic efficiency will be calculated using different scenarios for energy price increases.

The HP4NZEB project will provide valuable information for the entire construction industry, for both new construction and renovation. In order to utilize international expertise, the project participates in international information exchange in the Annex collaboration of the International Energy Agency’s Heat Pump Program.

In addition to participating companies such as Ensto Enervent, the project partners include the Finnish Heat Pump Association SULPU, VTT and Aalto University. The project is part of Tekes’ Witty City 2013–2017 program and ends in fall 2015.


REFERENCES AND ADDITIONAL INFORMATION

REFERENCES AND ADDITIONAL INFORMATION

The National Building Code of Finland, sections D2, D3 and D5www.finlex.fi

www.ym.fi/fi-FI/Maankaytto_ja_rakentaminen/Lainsaadanto_ja_ohjeet/Rakentamis-maarayskokoelma/Suomen_rakentamismaarayskokoelma(3624)

Good and healthy indoor airwww.allergia.fi

www.hengitysliitto.fi

www.hengitysyhdistys.fi

www.sisailma.info.fi

www.sisailmayhdistys.fi

www.sauna.fi

www.tsy.fi

Energy efficiencywww.ekosuunnittelu.info

www.motiva.fi

www.sulpu.fi

www.sulvi.fi

www.tukes.fi › ... › Electrical equipment › Requirements for electrical equipment

www.ym.fi... The Ecodesign Directive and the Energy Labelling Directive

Energy-efficient constructionec.europa.eu/energy/efficiency/consultations/.../fi_directive2013.pdf www.energiaviras-to.fi/ekosuunnittelu

www.erms.fi/cms/fi/vihreae-rakentaminen

www.greennetfinland.fi/fi/index.php/HP4NZEB

www.promise-luokitus.fi

www.eemontti.fi

figbc.fi

www.passiivi.info

www.renzero.fiwww.frame-finland.fi______www.wikipedia.fi

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