HVAC Energy Efficiency Ventilation, indoor air & heating installations

HVAC adjustments and implementation

Energy efficiency of technical installations is influenced by:

• The choice of the appliance, systems and their consistencies

• The routes and insulation of the ducts and pipes• Compactness of ducts, through-holes and rooms• The purity of louvres, filters and valves • Fine-tuning the system and automation control• Use and maintenance

Ventilation and indoor air

• Ventilation is one of the most significant parts of a building’s energy consumption.

• Ventilation brings fresh air from outside to inside. Impurities are then removed from the inside air.

• Impurities:• Carbon dioxide, moisture, dust, toxins, allergens, smoke from kitchen

• Discharges from building materials and furniture.

• Deficient ventilation causes:• Stuffiness, smells

• Increased carbon dioxide - headache and exhaustion

• Moisture condensation – moisture damage

• Favourable habitat for microbes

• The air must move freely between different rooms• Remember threshold gaps, keep doors open,…

Ventilation

Good quality indoor air• good supply of fresh air• the recommended temperature of the

room is 20-22o C; under 18o C and over 23o C can cause health problems

• air flow in the rooms, according to rules, is 0.2 m/s, recommended is 0.1 m/s

• good indoor air has less than 900 ppm of co2 (co2 is a good indicator of air quality)

• the picture shows an indicator used to

measure air quality

• All the air is changed every 2 hours. (ventilation rate 0.5 1/h).

• In an empty building at least 0.2 times in an hour.

• Fresh air per person is 6 litres per second meaning 21m3/h (adjustment if necessary)

• Fresh outside air is brought to bedrooms and living rooms. • Bedroom 0.5 l/s/m2

• Living room e 0.5 l/s/m2.

• The air is removed from the rooms with a lot of moisture or impurities. • kitchen 8 - 25 l/s

• bathroom 10-15 l/s

• utility room 8-15 l/s

• toilet 7-10 l/s

• sauna 2 l/s/m2

• walk-in closet, stores 3 l/s.

Amount of ventilation

Natural ventilation

In natural ventilation, the warm air goes out through the flue and fresh air is brought in through valves on the walls.

Natural ventilation• Common until the 1960s

• Natural ventilation is based on lighter warm air rising. The differential pressure is created between indoor and outdoor air because of temperature differences.

• In the winter, the temperature difference between indoor and outdoor air is huge, so the differential pressure is also huge so ventilation is working well.

• In warm seasons, for example, oil heating warms the flue and encourages natural ventilation. (Usually, a brick flue is the exhaust route for the air)

• A good supply of air has to be ensured (ventilators, window ventilators)

• Keeping carbon dioxide at the target level usually requires constant airing (windows).

• Closing a ventilator because of draught is a common problem.

• Regular cleaning of ventilators is a general overhaul.

Example of 150 m2 house with natural ventilation

Supply air downstairs: • 3 ventilators• 1 ventilation window

ajar (1cm)

Exhaust air:• Downstairs bathroom 1

exhaust air ventilator • Upstairs bedrooms the window

is ajar and one exhaust air ventilator is over the window

Air quality:• Outdoor temperature -25o C• Two persons on both floors.• The carbon dioxide rate

upstairs stays acceptable in the bedrooms

Mechanical extraction

• Common in the 1960-1990’s• Air is removed by fan• Adjustment usually by the

cooker hood• Requires sufficient fresh air

and transfer air routes• Closing the valves because of

draught is a common problem• The action of the fans must be

controlled • The valves must be cleaned

regularly

Mechanical extraction

Outdoor air

Bedroom

Living room

Transferred air

Kitchen

Fan

Bathroom

Exhaust air

Picture: Sisäilmayhdistys

Mechanical input and extraction ventilation• The air is brought in and removed by

fans. • Accurate adjustment; the weather does

not affect ventilation.• The supply air is filtered and pre-

heated if needed.• By heat recovery, the energy of

exhaust air can be brought back to the building.

• The building is usually designed 0-10 Pa below the pressure of the outdoor air so moisture damage in the structures can be avoided. The envelope of the building must be absolutely tight.

• In old buildings, low pressure can absorb microbes in the indoor air.

BedroomOutdoor air

Fan

Living room Kitchen

Mechanical input and extract ventilation

Air supply unit, heat recovery

Bath room

Outdoor air

Exhaust air

Supply air (heated)

Transferred air

Fire place switch

Picture: Sisäilmayhdistys

Cooker hood

Heat recovery• A significant part of heating energy from exhaust air can be recovered

by heat exchangers.

• The supply air is heated by the heat content of the exhaust air or the heat is transferred to the drinking water by the exhaust air heating pump.

• The use of heat recovery requires buildings to be tight.

• The efficiency of a modern heat recovery appliance is approx. 80%.

Example

+22

+12

-5

+13

Fresh air Exhaust air

Supply airExtract air

Bridging airBridging sheet

Bridging sheet

Heating

Heat production methodsRenewable energy and hybrid systems are becoming more common

Air source heat pumps ASHP• In Finland, about 500,000 ASHPs were installed before 2014 producing

5 TWh of energy per year. By 2020, an additional

500,000 air heat pumps are estimated to be installed.• Residential buildings use 200,000 boilers, 100,000 other water

circulation heating systems and 500,000 electric heating systems. Air heat pumps are also very suitable and can even replace existing pumps.

• There are 36,000 exhaust air systems in apartment buildings. An exhaust air heat pump is a good energy-saving device in apartment buildings. It can reduce energy costs by 40-50%.

• The energy company can not increase the price of energy just because there is an air source heat pump in the apartment building.

• The compressors of the air heat pumps are reliable but the failures of the installation, adjustment or use can reduce the benefits of the air heat pump.

• Users need clear written instructions and personal guidance on their use.

Features of ASHPs• The efficiency COP of ASHPs indicates how efficiently used electric energy can be

changed to heating energy. COP value is measured always in temperature of +7 degrees. For example, number 4 means that one kilowatt of the electricity taken from the grid has produced 4 kilowatt of heating power.

• The coefficient of performance of the heating period, SCOP, is calculated for four different kind of heating. Europe has been divided into three different climatic zones. The northernmost zone is based on the climate of Helsinki. That value is not always presented in the brochures of the ASHP.

• EER means the cooling efficiency factor. A good EER value is over 3.5.

• SEER means a yearly cooling efficiency factor. Usually that is not a very substantial criterion in Finland.

• A Swedish survey demonstrated that the SCOP values of the geothermal heat pumps in the 2010’s in floor-heated houses were 3.5-5 and in radiator heated-houses 3.0-4.

• The SCOP values of the air/water heat pumps in southern Sweden were 1.8-3.0 in radiator- heated houses and the SCOP values of the air heat pumps were 2.8-3.4 (average temperature 6.1o C)

• In northern Sweden the SCOP values of the ASHPs were 1.7-2.6 (average temperature +1.3o C)

Comparing and choosing an ASHP

• ASHPs are suitable as the primary heating method in new buildings and as an secondary heat source in old buildings.

• When choosing an ASHP consider:• SCOP, climate and purchase price.

• The existing heat distribution method: an old one with a sheet radiator does not achieved the best efficiency of an air/water heat pump or a geothermal heat pump. A lower floor temperature raises the efficiency of pumps.

• The indoor air can be cleaned and the temperature of the room can be adjusted fast and flexibly with an ASHP. But the interior requires regular cleaning.

• With floor heating, the air/water heat pump and the geothermal heat pump give comfort and ease of use.

Hybrid systemsA hybrid system means a common use of heat production methods. Heat air pumps are usually used with hybrid systems. • In hybrid systems the energy is first taken from the heat air pump and when

the capacity of the heat pump is reached, heat is taken from other sources. • Usually a slightly smaller (part power heat pump design) is the most

economical. At the coldest time the fireplace or electric heating is also used. This also saves the depth of the bore well of the geothermal heat pump.

• Hankinnan yhteydessä tulee eri mitoitusvaihtoehtoja vertailla ja varmistaa, että tarjousten mitoitukset ovat vertailukelpoisia.

• The inner unit of the ASHP is installed in the room. It should be as big and clear as possible and.

• Other heaters must be adjusted to the lowest temperature in the area covered by the inner unit.

• In the room where the air heat pump is situated, the temperature is adjusted to a higher limit than the other rooms. Then the warm air is eddied to the other rooms.

• Optimising the use of three different heat sources is difficult. • Proper adjustment must be tested in both the cold and the warm season.

Solar heating since 1985

There is a huge variation in temperatures of solar collectors→thermal radiation in the

fasteners, junctions and penetration

→thermal radiation in the pipes→boiling and evaporating of the

liquid→danger of over heating and

fire →Insulation and sealing

Heat distribution• The pre-set control of heat distribution must take into consideration that the

rooms in the corners of the building and the lower floors need more heating. Also heat loads like solar radiation and the delays based on the charging capacity of the structures need to be considered.

• In low-energy houses, the variation of inner heat loads has a quick and significant effect on heat demand. Variations in outdoor temperatures have a slow and minor effect on heat demand.

• Radiator heating is easy to adjust, but requires

relatively hot water.• The low temperature of floor heating feels nice but

means high heating power. Slow control can cause

over heating.• Insulating heat pipes and the pipes of warm circulation water is important

because of heat loss and heat loads.• Temperature, comfort, air flows and draught must also be taken into account. • To eliminating draughts and ”cold radiation”, the heating can be adjusted to a

lower temperature.

• Reducing the temperature 1o C reduces the need for heating by 5%.

HVAC Installation

Installation routes

When installing ducts and pipes consider:• Making sizes of ducts and reductions

according to the plans

• Minimizing pressure losses by avoiding unnecessary corners and bends.

• Allowing enough space for duct and pipe insulation and other installations• Ventilation ducts, HEVAC-pipes, cable trays,

insulations, luminaires

• Pumps, dampers, sound traps,

• Indicators, thermostats, sensors,…

Installation routes must be agreed• Cooperation with all service installers on site is essential.

• The principles for layout, at least of corridors and flues, must be agreed beforehand. Places for insulation must also be marked.

• Cooperation with designers is also important. For example, ask designers for the cross-sections of the corridors near heat distribution rooms and ventilation plant rooms.

• Insulate supply air ducts properly in cold spaces. • Confirm that settling of insulation under the ducts will not cause a cold air hollow.• Fit wool mats, for example, between the trusses, the disposition of ducts near the

truss and loose-fill insulation above. Make loose-fill insulation compact if needed.• If possible, install the warm pipes on the warm side of insulation and the cold

pipes to the cold side of insulation. • Condensate insulation is needed, for example, with:

• Supply air ducts in warm spaces• Stack vents in warm spaces• Cold running water in warm spaces• Insulation of return air ducts in cold spaces

• Make through-holes in the envelope

very properly together with structural

work.

Installing and insulating roofs

Duct insulation

• Joints are overlapped using multi layered insulation.

• Transverse seams are positioned where the fasteners are.

• Longitudinal seams always face downwards if possible.

• Insulation joints with aluminium surfaces are always taped with aluminium tape.

• The resistance of the insulation is ensured by taping steel wire around the pipe with a 250 mm-gap between the bonds.

The appropriate use of electricityChoose electric appliances and systems which can be controlled appropriately.• The running power of the ASHPs and the ventilation units can be reduced when the house is empty.. • The temperature can be reduced at night.• The floor heating can be controlled by a thermostat and a timer switch when the heating is needed less• Laundering and washing-up can be programmed to be done at night when electricity consumption is low. It will reduce the bill from the energy company and can affect the pricing of electricity. • Nowadays the consumer can buy electricity on an hourly tariff.• Using a timer switch to pre-heat cars and to charge electric cars according to outdoor temperature and during the off-peak tariff time • Adjusting the lighting in rooms and outdoors with a timer switch, by the pecu switch and motion detectors. The start values set energy efficiently but consider the need for lighting• The heating of electric sauna stoves and hot-water tanks can be rotated with the heating of

the rooms by an electricity load control system • The appliances with A+++ are recommended.

Fine-tuning and commissioning HVAC

Energy efficiency of building automation installations

• In the installations of thermostats and sensors must be noticed the cooling or warming effects of other devices and systems like solar radiation, supply air, cool surfaces

• The controlling apparatus of the appliances are clearly named. For example time switches are named in words, not with codes.

• Outside the switchboard door is marked the info of the switches and inside the room the instructions of the switches are stored.

• The controls are set case-specific and appropriate with the users .

• The heating and ventilation can be controlled apart from time switches and temperature sensors with moisture and carbon dioxide sensors, move detectors and by measuring the sunlight.

• The appropriate control of heating can reduce the need for heating energy and even improve the heat comfort – The places where people stay are heated.

• Before commissioning the building, the HVAC systems must be tested and adjusted with the help of functional tests. • adjustment of the air amount• pre-adjustment of the radiator ventilators• the operation of thermostats and sensors• the measurement of temperatures• the survey of the effects of heat load• testing the cooperation of the systems • the copies of functional diagrams and field books are left in

the engine room and in the heat distribution room• ensuring the operation of the control, alarm and report

systems• the users of the systems are guided to use the systems

properly• There must be enough time for functional tests.• The rooms must be able to close (the doors shut), so

the measurements are reliable.• During the functional test can not be done any building

works anymore.

Commissioning the HVAC

AC-engine room in Ideapark

Heat exchanger

Synchronizing the systems

• The heating and cooling should not be used at the same time. Fading between heating and cooling must be prevented: allow enough time between.

• Thermostats and sensors must be installed in places where there is no extra heat load or cooling.

• Notice:• ventilation air supply

• external heat loads e.g. solar radiation

• lights

• the blast from the appliances.

Thermostats should not be covered by fittings, curtains, towels, etc.

Remember• Tight structures and through-holes and proper insulated

installations are the basis for an energy-efficient HVAC. • The design and adjustment of hybrid systems is challenging.

Testing is important.• The operating system must control:

• Quality, warmth and moisture of the air

• Carbon dioxide, volume of air and air flow

• Energy consumption

• Maintenance e.g. cleaning the ventilation filters.

• How people use the system has a major effect on energy consumption. Users must learn how to use the system.

• There are many ways of reducing energy consumption which may even increase the comfort of the building.

The sole responsibility for the content of this publication lies with the authors. It does not necessarily reflect the opinion of the European Union. Neither the EASME nor the European

Commission are responsible for any use that may be made of the information contained therein.

The good practices and principles required for the energy efficient building have been included in the teaching material. The writers are not responsible for their suitability to individual building

projects as such. The individual building projects have to be made according to the building design of the targets in question.