27th elementary school of piraeus final version

Activity report: Energy performance and

climatic conditions in public spaces in the

MED area / Step-by-Step Energy Retrofit

Methodology for the 27th Elementary

School of Piraeus, Greece according to the

Passive House Standard

Deliverable No. P8

Component No.5-Pilot testing of the methodology, Evaluation and Capitalization

Phase No. 5.6- Final set of applications and Development of a strategic plan to introduce

outcomes in the wider EU area

Contract No.: 1C-MED12-73

Axe2: Protection of the environment and promotion of a sustainable territorial development

Objective 2.2: Promotion of renewable energy and improvement of energy efficiency

Authors:

Submission date: 20/5/2015

Status: Final

May 2015

1

Contents

1. General ....................................................................................................................................................................... 3

2. Building description .................................................................................................................................................... 4

2.1 Building identification data ........................................................................................................................................ 4

2.2 Building operational schedule .................................................................................................................................... 6

2.3 Existing Building data ................................................................................................................................................. 7

2.3.1 Design ........................................................................................................................................................................ 7

2.3.2 Building Envelope .................................................................................................................................................... 10

2.3.3 Energy Balance Winter ............................................................................................................................................ 17

2.3.5 HVAC- Lightning ...................................................................................................................................................... 20

3 The Passive House Standard .................................................................................................... 23

3.1 Introduction.............................................................................................................................................................. 23

3.2 Passive House Criteria .............................................................................................................................................. 26

3.3 EnerPHit Standard for existing buildings .................................................................................................................. 28

3.4 Occupant Satisfaction ............................................................................................................................................... 32

3.6 Boundary conditions for the PHPP calculation .......................................................................................................... 36

3.7 Passive House Standard for Schools .......................................................................................................................... 39

3.7.1 The Air Quality Issue ............................................................................................................................................... 39

3.7.2 The Requirements ................................................................................................................................................... 40

4 The Enerphit Procedure for the 27th Elementary School ............................................................ 43

4.1 General ................................................................................................................................ 43

4.2 The building envelope .............................................................................................................................................. 46

4.2.1 The opaque elements ............................................................................................................................................. 46

4.2.2 Transparent Elements ............................................................................................................................................. 49

4.3 The new Ventilation System with Heat Recovery ...................................................................................................... 52

4.4 Heating and cooling ................................................................................................................................................. 56

4.5 The overall results of the passive house retrofit ....................................................................................................... 57

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4.5.2 The summer situation (monthly method) .............................................................................................................. 58

5 Comparison of PASSIVE HOUSES Step-by-Step Approach & KENAK............................................ 62

Calculation of the primary energy use is reliable due to the use of the total unadjusted final energy

consumption and can be used successfully for checking compliance with the PE limit value. ............ 77

6 Conclusion ............................................................................................................................... 84

7 How to go about it ................................................................................................................... 85

8 References ............................................................................................................................... 86

Stefanos Pallantzas, Civil Engineer, Certified Passive House Designer .............................................. 86

3

1. General

In the present deliverable, a detailed presentation of the retrofit methodologies and results will be given,

concerning a selected building (the PILOT BUILDING) of the ones that are illustrated in the deliverable D.7.

The criteria for selecting one of the three potential buildings are the followings :

- Present building status (structural, schedule, operations, etc)

- Potential for retrofit results

- Complexity of the building envelope

- Potential of multiplication effect for the study outcomes for similar buildings in Municipality

- Available info for structural items (insulation studies, etc)

- Competence of building info folder

Based on the above info, the studding team, together with the technical board of the municipality of Piraeus,

has decided to run the retrofitting study for the case of the 27th Elementary School (THE PILOT BUILDING).

Under the philosophy that moves the REPUBLIC-MED program and concerns the nomination of approaches and

methods to intensify the imagination and innovation that is documented with scientific approaches, will be

performed analysis, based on the principles of an international standard and Liabilities building, the existing

energy behavior and scenarios proposed situation the pilot building. For this building (the PILOT BUILDING), it

will be implemented the above actions (1) and (2), and based on the passive house standard and compare the

results obtained from the two methodologies as:

A) The accuracy of calculations the status quo: Comparison between measurements and calculations of the

National methodology and Passive House Standard.

B) The upgrading and investment cost measures: comparison between the measures and the costs provided by

the National methodology and Passive House Standard.

It will also investigate the feasibility and feasibility of the annual renovation of the building, with the following

actions:

• Hint energy upgrade measures that can be applied for each year until 01.01.2019.

• Identify the Cost per year.

• Description of measurements and control of energy efficiency of a building over the course of the progressive

project.

• Guidelines for identifying funding opportunities to implement progressive project with examples of similar

projects.

The application of models for both Passive House Standard and KENAK will be made by highly experienced and

certified designers, aiming at optimum efficiency models.

4

2. Building description

2.1 Building identification data The 27th elementary school in Piraeus is located at 37°57’ N and 23°37’ E. The school consists of two connected

buildings and a courtyard. The building consists of the ground floor, the first and the second floor. The boiler

room is located on the ground floor. The 27th elementary school was built in 1987.

Figure 1 : depicts the geographical location of the school

The basic data of the building (according to plans, data provided and on-site measurements) are :

5

Location Piraeus Climatic Zone (PHPP) GR002a - Athinai

Total Floor area (m2) 1640 Treated Floor Area (PHPP,

m2)

1264

Total Volume (m3) 5014 Conditioned Volume

(PHPP,m3)

4044

Total Thermal Envelope

(PHPP,m2)

2913 Total Windows Area

(PHPP,m2)

335

Number of floors Ground Floor + 2

Table 1 : Info data for the building under consideration

6

2.2 Building operational schedule

The school operates from the 11th of September until the 15th of June from Monday to Friday. During this

period, the school remains closed for approximately 15 days for Christmas holidays and 15 days for Easter

holidays.

The school operates in two shifts. The first shift operates from 08:00 until 14:00. The number of pupils and

teachers in the first shift is 237 and 24 respectively. The second shift operates from 14:00 until 16:15. The

number of pupils and teachers in the second shift is 45 and 2 respectively. In this shift, only two classrooms in

the ground floor are operational.

Each classroom accommodates approximately 20-23 pupils. The main operational characteristics of the 27th

elementary school are:

Occupancy schedule 08:00 – 14:00

14.00 - 16.15

Total number of pupils 237

45

Average occupancy hours 1st shift: 6h

2nd shift: 2h, 15 min

Total number of

teachers & staff

24

Table 2 : Schedule for the building under consideration

7

2.3 Existing Building data

2.3.1 Design

The whole building is oriented in the north-south direction. The main entrance of the building is on the north

facade. The building envelope has not been renovated since its construction in 1987.

Figure 2 : North Façade Figure 3: South Façade

The layouts of the ground, first, second floors and the elevations are presented in the Figures 4, 5, 6 , 7 and 8

respectively.

Figure 4 : Ground floor

8

Figure 5: 1st floor

Figure 6: 2nd floor

9

Figure 7: North and East Elevations

Figure 8 : South and West Elevations.

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2.3.2 Building Envelope 2.3.2.1 Opaque elements

The construction is a concrete-brick construction. Erker slabs have been used a lot as an architectural feature of

the building. The walls of the school are in a good condition without evident signs of moisture or leakage

problems. According to the plans and the building permission, the walls are built with bricks and are thermally

insulated.

Tables 3, 4 and 5 presents the thermal characteristics of the walls as inputted in the PHPP.

Bauteil Nr. Bauteil-Bezeichnung Innendämmung?

01ud Ext.wall_brick

Wärmeübergangsw iderstand [m²K/W]

Ausrichtung des Bauteils 2-Wand innen Rsi 0,13

Angrenzend an 1-Außenluft außen Rsa 0,04

Teilf läche 1 l [W/(mK)] Teilf läche 2 (optional) l [W/(mK)] Teilf läche 3 (optional) l [W/(mK)] Dicke [mm]

Plaster 0,872 20

Brick 0,523 90

Glass wool 0,041 50

Brick 0,523 90

Plaster 0,872 20

Flächenanteil Teilf läche 1 Flächenanteil Teilf läche 2 Flächenanteil Teilf läche 3 Summe

100% 27,0 cm

U-Wert-Zuschlag 0,10 W/(m²K) U-Wert: 0,662 W/(m²K)

11

Concerning these figures, we have increased the U-values by 10% in order to include also all thermal bridges of

the outside walls. We also have decreased proportionally the insulation referring to the concrete elements,

because part of their surface is uninsulated.

Bauteil Nr. Innendämmung?

02ud Ext.wall_conc.





Plaster 0,872 20

Brick 0,523 60

Glass wool 0,041 50

Reinforced concrete 2,030 300

Plaster 0,872 20


70% 30,0% 45,0 cm

0,10 W/(m²K) U-Wert: 2,000 W/(m²K)


03ud Erker slab_


Ausrichtung des Bauteils 0,1 innen Rsi 0,10



Marble tiles 1,100 50


plaster 0,872 20


100% 22,0 cm

0,10 W/(m²K) U-Wert: 3,643 W/(m²K)

12

Figure 9: Thermal bridges and uninsulated concrete elements

There are two types of roofs in the school; a flat roof mainly and a sloped roof only in a small part of the school.

Both roof types are thermally insulated. Table 6 and Table 7 present the thermal characteristics of the roofs.


05ud Flat roof


Ausrichtung des Bauteils 1-Dach innen Rsi 0,17



Plaster 0,870 10

Concrete slab 2,040 150

Light concrete 0,290 100

Cement mortar 1,400 20

Hydroinsulation 0,230 10

Extruded polystyrene 0,034 100

Gravel 2,000 50


100% 44,0 cm

0,10 W/(m²K) U-Wert: 0,373 W/(m²K)

13

Figure 10: Flat Roof Figure 11: Sloped Roof

The floor in contact with the ground is covered by marble tiles and is thermally insulated. Table 8 presents the

thermal characteristics of the floor.


06ud Sloped roof





ALUMINIUM SHEET 160,000 5

Insul. Sandwich panel 0,025 100

ALUMINIUM SHEET 160,000 5


100% 11,0 cm

0,10 W/(m²K) U-Wert: 0,338 W/(m²K)

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2.3.2.2 Transparent Elements

There are three types of openings in the building: windows, doors and glass blocks. The windows are double

glazed with aluminum frame and the doors are made of steel. The U value of the windows is 3,7 W/m2K (12 mm

air gap), of the metal doors is 5,8 W/m2K and of the glass blocks is 3,5 W/m2K.

The total area of the building’s openings (including the glass blocks) is approximately 335 m2. The following

Figures depict views of the windows, doors and glass blocks.

Figure 12 : Aluminium windows Figure 13 : Steel Exterior Doors


04ud Ground Floor slab


Ausrichtung des Bauteils 3-Boden innen Rsi 0,10

Angrenzend an 2-Erdreich außen Rsa 0,00




Glass wool insulation 0,041 50

Sand 0,580 20

Concrete gravel 0,810 200


100% 47,0 cm

0,05 W/(m²K) U-Wert: 0,631 W/(m²K)

15

Figure 14: Glass blocks Figure 15 : Glass blocks and Windows in the South facade

In the following table (9), one can see the characteristics of the transparent elements, as shown in the PHPP.

Verglasungen Verglasungen

Als Startkomponente für die Optimierung empfohlene Verglasung:

2-fach Wärmeschutzglas (Bitte Behaglichkeitskriterium beachten!)

ID Bezeichnung g-Wert Ug-Wert

W/(m²K)

01ud Existing double glazed windows 0,77 2,90

02ud Glass blocks 0,30 3,50

03ud Existing 5,70

Fensterrahmen Fensterrahmen

Uf-Wert Rahmenbreite Glasrand Wärmebrücke Einbau Wärmebrücke

ID Bezeichnung links rechts unten oben links rechts unten obenYGlasrand

links

YGlasrand

rechts

YGlasrand

unten

YGlasrand

oben

YEinbau

links

YEinbau

rechts

YEinbau

unten

YEinbau

oben

W/(m²K) W/(m²K) W/(m²K) W/(m²K) m m m m W/(mK) W/(mK) W/(mK) W/(mK) W/(mK) W/(mK) W/(mK) W/(mK)

01ud Metal frame not insulated 5,50 5,50 5,50 5,50 0,060 0,060 0,080 0,080 0,030 0,030 0,030 0,030 0,088 0,088 0,088 0,088

02ud Glassblock 0,88 0,88 0,88 0,88 0,001 0,001 0,001 0,001 0,100 0,100 0,100 0,100 0,100 0,100 0,100 0,100

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2.3.2.3 Shading

The building is situated in a densely built urban area. Big Buildings are shading the school, especially the south

façade. The sloped roof of the Auditorium is blocking a big part of the south façade of the 1st floor. There is no

external shading system for the windows in the building.

2.3.2.4 Airtightness

We have assumed in our calculations that the airtightness of the building is very poor, according to experience

from the majority of the existing building stock in Greece.

OrientationGlobal-

RadiationShading

Ver-

schmut-

zung

Non-vertical

RadiationGlass part g-Value Reductionfactor Radiation Window Area

Window

U-ValueGlass area

Average

radiation

Standardwerte → kWh/(m²a) 0,75 0,95 0,85 m2 W/(m2K) m2 kWh/(m2a)

Nord 25 0,56 0,95 0,85 0,75 0,65 0,34 158,39 3,95 118,61 25

Ost 50 0,10 0,95 0,85 0,78 0,77 0,06 13,50 3,68 10,47 50

Süd 95 0,53 0,95 0,85 0,78 0,61 0,33 124,19 3,94 96,63 95

West 49 0,29 0,95 0,85 0,93 0,38 0,22 38,11 3,85 35,35 46

Horizontal 80 1,00 0,95 0,85 0,00 0,00 0,00 0,00 0,00 0,00 80

Summe bzw. Mittelwert über alle Fenster 0,60 0,31 334,18 3,92 261,06

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2.3.3 Energy Balance Winter

According to the envelope characteristics and the airtightness of the building, the energy balance of the building

is shown in the following chart. In the left column the losses of the thermal envelope are shown. The main

problems are: windows, external walls and airtightness of the building. On the right column one can see that

the solar gains are very low. This is the reason why the energy demand, even in winter time, is very high.

Figure 16 : Energy Balance Winter by PHPP

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2.3.4 Energy Balance Summer

The following chart shows the temperature situation during summer. As one can see, the inside temperature

(yellow) of the building is often higher than the outside temperature (blue). This happens also during June and

September, when the school is operating.

Figure 17 : temperature situation during summer by PHPP

The energy balance of the Building during summer time is shown in the following chart. The same elements

(walls, roof, windows, lack of airtightness on the left column) lead to heat loads coming inside the building,

while huge internal heat gains (right column white) lead to a large cooling demand.

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Figure 18 : Energy Balance Summer by PHPP

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2.3.5 HVAC- Lightning 2.3.5.1 Heating / Cooling

The school has a central heating system. The central heating system dates back to the time when the school was

constructed in 1987. In 2004, there was a fuel switch from oil to natural gas by replacing the oil burner with a

natural gas burner. The boiler room is located on the ground floor of the school at the south side of the building.

The central heating system operates for approximately 4 months, from mid-November until the end of March

and the heating schedule daily is from 07.00 to 12.30, 5 days per week. The natural gas fired boiler is

manufactured by the Greek company “Therma”; its total heating capacity is 150.000 kcal/h (175 KW). This boiler

is extremely over-dimensioned, while the needs of the existing building are less than 75 KW.

A two-pipe system is used for hot water circulation throughout the building. The school building is heated by

cast iron radiators. The piping network in the boiler room, but also in the rest of the building, is not insulated. All

areas of the school are heated by radiators, including the circulation areas, except from the WC.

There is not any central cooling system in the school. A few old AC split units, with a total capacity of 26kW, are

located in the teachers’ offices and some other rooms. Some ceiling fans are also present.

Figure 19 : The Gas Boiler Figure 20 : Uninsulated pipes

Figure 21: Ceiling fans and splits Figure 22 : some fans in the Auditorium

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2.3.5.2 Lighting

The school is equipped with T8 fluorescent luminaires of 36 W with a cover. The average power in the

classrooms is approximately 13,5 W/m2 and in the circulating areas is 2,2 W/m2. It is noted that many of the

lighting fixtures are not operating and the lighting conditions are not sufficient.

Figure 23 : Insufficient lightning in all areas

Inserting all above data in the PHPP we’ve got the results for the energy consumption of the existing building as

follows:

Comments:

The heating and cooling consumption were expected. The building is mainly uninsulated, the quality of

the windows is very poor and the airtightness is poor. The building has a good orientation but the solar

gains are low because of the surrounding buildings. The indoor air quality is only controlled by opening

the windows, but this causes more energy demand for heating and cooling. Interviews with teachers

gave us information about them not being satisfied from the heating and cooling system and the air

Builiding Energy Consumption according toTFA and Year

Treated Floor Area m² 1263,8 Criteria Ok?

Heating Heating Demand kWh/(m²a) 56 ≤ 15 -

Heating Load W/m² 62 ≤ - -

Cooling Cooling Demand kWh/(m²a) 49 ≤ 15 16

Cooling Load W/m² 42 ≤ - 11

Overheating >25 % - ≤ - -

Humidification G39 (> 12 g/kg) % 0 ≤ 10 ja

Airtightness Blowerdoor Test n50 1/h 7,0 ≤ 1,0 nein

PE-Bedarf kWh/(m²a) 195 ≤ 201,792951 ja

PER-Bedarf kWh/(m²a) 174 ≤ - -

kWh/(m²a) 0 ≥ - -

2 leeres Feld: Daten fehlen; '-': keine Anforderung

Non Renewavble Energy

Renewable

Primary Energy

(PER)Erzeugung erneuerb. Energie

(Bezug auf überbaute Fläche)

-

nein

nein

Aleternative

Criteria

22

quality. The final demand is on this level because of the climate conditions and due to the fact that the

school is closed during the hot period of summer.

The Primary Energy demand is lower than expected. This is because the heating system, which has very

high losses due to the uninsulated pipe system, doesn’t work more than 4 hours/day and the lightning

system is very poor. The measured consumptions during the last years are even lower, because of the

financial crisis.

There is a big potential to reduce the energy demand of the school using the passive house standard

and this is what will be analyzed in the following sections.

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3 The Passive House Standard

3.1 Introduction

Passive House is a building standard that is truly

energy efficient, comfortable and affordable at the

same time. Passive House is not a brand name, but

a tried and true construction concept that can be

applied by anyone, anywhere.

Yet, a Passive House is more than just a low-energy

building:

Passive Houses allow for space heating and cooling

related energy savings of up to 90% compared with

typical building stock and over 75% compared to

average new builds. Passive Houses use less than

1.5 l of oil or 1.5 m3 of gas to heat one square

meter of living space for a year – substantially less

than common “low-energy” buildings. Vast energy

savings have been demonstrated in warm climates

where typical buildings also require active cooling.

Passive Houses make efficient use of the sun, internal heat sources and heat recovery, rendering conventional

heating systems unnecessary throughout even the coldest of winters. During warmer months, Passive Houses

make use of passive cooling techniques such as strategic shading to keep comfortably cool.

Passive Houses are praised for the high level of comfort they offer. Internal surface temperatures vary little from

indoor air temperatures, even in the face of extreme outdoor temperatures. Special windows and a building

envelope consisting of a highly insulated roof and floor slab as well as highly insulated exterior walls keep the

desired warmth in the house – or undesirable heat out.

A ventilation system imperceptibly supplies constant fresh air, making for superior air quality without

unpleasant draughts. A highly efficient heat recovery unit allows for the heat contained in the exhaust air to be

re-used.

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Typical heating systems in

Central Europe, where the

Passive House Standard was

first developed and applied, are

centralized hot water heating

systems consisting of radiators,

pipes and central oil or gas

boilers. The average heating

load of standard buildings in

this area is approximately 100

W/m² (approx. 10 kW for a 100

m² apartment). The Passive

House concept is based on the

goal of reducing heat losses to

an absolute minimum, thus

rendering large heating systems

unnecessary. With peak heating

loads below 10 W per square meter of living area, the low remaining heat demand can be delivered via the

supply air by a post heating coil (see box below). A building that does not require any heating system other than

post air heating is called a Passive House; no traditional heating (or cooling) systems are needed.

The Passive House concept itself remains the same for all of the world’s climates, as does the physics behind it.

Yet while Passive House principles remain the same across the world, the details do have to be adapted to the

specific climate at hand. A building fulfilling the Passive House Standard will look much different in Alaska than

in Zimbabwe.

In ‘warm climates’, reducing the space heating demand is a concern but in addition, avoiding overheating in

summer by passive or active cooling strategies become highly relevant for the building optimization. The

improved building envelope of a Passive House helps to minimize external heat loads (solar and transmission).

In addition, well-known shading solutions in warm climates, such as fixed and moveable shading devices (in

order to minimize heat loads), as well as cross night ventilation (passive cooling) are important measures for

Passive Houses.

Regarding summer comfort, the internal heat loads must be minimized e.g. energy efficient appliances should

be focused on.

First certified Passive Houses in warm climates show the optimization potential in design and execution. While

lower levels of insulation are sufficient for moderate and warm climates such as the majority of the

Mediterranean region, high levels of insulation in opaque elements of the building envelope are required for

extremely hot climates.

25

To achieve cost-efficient solutions, the resulting insulation thicknesses call for optimized compactness of the

building shape. Windows should meet the comfort and energy requirements, and the designer should be aware

of the high influence of the best orientation.

Very good airtightness is important in all climates, and especially for hot and humid climates [Schnieders et. al.

2012]. Active cooling could be avoided in so-called ‘Happy climates’, but is mandatory for very warm climates

(for instance Granada, Spain).

Ventilation strategies include natural ventilation in summer as well as mechanical ventilation (extract air system

only or ventilation system with heat exchanger and summer bypass). For cost effective Passive Houses in warm

climates component performance should be in the focus of all stakeholders.

26

3.2 Passive House Criteria

Passive Houses are characterized by an especially high level of indoor comfort with minimum energy

expenditure. In general, the Passive House Standard provides excellent cost-effectiveness particularly in the

case of new builds. The categories Passive House Classic, Plus or Premium can be achieved depending on the

demand and generation of renewable primary energy (PER).

1The criteria and alternative criteria apply for all climates worldwide. The reference area for all limit values is the

treated floor area (TFA) calculated according to the latest version of the PHPP Manual (exceptions: generation

of renewable energy with reference to ground area and airtightness with reference to the net air volume).

2 Two alternative criteria which are enclosed by a double line together may replace both of the adjacent criteria

on the left which are also enclosed by a double line.

3 The steady-state heating load calculated in the PHPP is applicable. Loads for heating up after temperature

setbacks are not taken into account.

4 Variable limit value subject to climate data, necessary air change rate and internal moisture loads (calculation

in the PHPP).

5 Variable limit value subject to climate data, necessary air change rate and internal heat and moisture loads

(calculation in the PHPP).

6 The steady-state cooling load calculated in the PHPP is applicable. In the case of internal heat gains greater

than 2.1 W/m² the limit value will increase by the difference between the actual internal heat gains and 2.1

W/m².

27

7 Energy for heating, cooling, dehumidification, DHW, lighting, auxiliary electricity and electrical appliances is

included. The limit value applies for residential buildings and typical educational and administrative buildings. In

case of uses deviating from these, if an extremely high electricity demand occurs then the limit value can also be

exceeded after consultation with the Passive House Institute. Evidence of efficient use of electrical energy is

necessary for this.

8 The requirements for the PER demand and generation of renewable energy were first introduced in 2015. As

an alternative to these two criteria, evidence for the Passive House Classic Standard can continue to be provided

in the transitional phase by proving compliance with the previous requirement for the non-renewable primary

energy demand (PE) of QP ≤ 120 kWh/(m²a). The desired verification method can be selected in the PHPP

worksheet "Verification". The primary energy factor profile 1 in the PHPP should be used by default unless PHI

has specified other national values.

28

3.3 EnerPHit Standard for existing buildings

The Passive House Standard often cannot be feasibly achieved in older buildings due to various difficulties.

Refurbishment to the EnerPHit Standard using Passive House components for relevant structural elements in

such buildings leads to extensive improvements with respect to thermal comfort, structural integrity, cost-

effectiveness and energy requirements.

The EnerPHit-Standard can be achieved through compliance with the criteria of the component method (Table

8) or alternatively through compliance with the criteria of the energy demand method (Table 9). Only the

criteria of one of these methods must be met. The climate zone to be used for the building's location is

automatically determined on the basis of the chosen climate data set in the Passive House Planning Package

(PHPP).

As a rule, the criteria mentioned in Table 8 correspond with the criteria for certified Passive House components.

The criteria must be complied with at least as an average value for the entire building. A higher value is

permissible in certain areas as long as this is compensated for by means of better thermal protection in other

areas.

In addition to the criteria in Table 8 or Table 9, the general criteria in Table 10 must always be met. The EnerPHit

categories Classic, Plus or Premium may be achieved depending on the demand and generation of renewable

primary energy (PER).

29

Table 8 : EnerPhit criteria for the building component method

Table 9 : Enerphit criteria for the energy demand method

30

Table 10 : General EnerPhit criteria

The PHI Low Energy Building Standard is suitable for buildings which do not fully comply with Passive House

criteria for various reasons.

Table 11 : PHI Low Energy Building Criteria

Besides a high level of energy efficiency, Passive House buildings and buildings refurbished to the EnerPHit

Standard offer an optimum standard of thermal comfort and a high degree of user satisfaction as well as

protection against condensate related damage. In order to guarantee this, the minimum criteria mentioned

below must also be complied with in addition to the criteria in Sections

Frequency of overheating. Percentage of hours in a given year with indoor temperatures above 25 °C

o without active cooling: ≤ 10 %

31

o with active cooling: cooling system must be adequately dimensioned

Frequency of excessively high humidity. Percentage of hours in a given year with absolute indoor air

humidity levels above 12 g/kg

o without active cooling: ≤ 20 %

o with active cooling: ≤ 10 %

The criteria for the minimum level of thermal protection according to Table 12 are always applicable irrespective

of the energy standard and must be complied with even if EnerPHit exemptions are used. They apply for each

individual building component on its own (e.g. wall build-up, window, connection detail). Averaging of several

different building components as evidence of compliance with the criteria is not permissible.

Table 12 : Criteria for minimum thermal protection

32

3.4 Occupant Satisfaction

All living areas must have at least one operable window. Exceptions are possible in justified cases as long as

there is no significant likelihood of occupant satisfaction being affected.

It must be possible for the user to operate the lighting and temporary shading elements. Priority must be given

to user-operated control over any automatic regulation.

In case of active heating and/or cooling, it must be possible for users to regulate the interior temperature for

each utilization unit.

The heating or air-conditioning technology must be suitably dimensioned in order to ensure the specified

temperatures for heating or cooling under all expected conditions.

Ventilation system:

o Controllability: The ventilation volume flow rate must be adjustable for the actual demand. In

residential buildings the volume flow rate must be user-adjustable for each accommodation unit

(three settings are recommended: standard volume flow / standard volume flow +30 % /

standard volume flow -30 %).

o Ventilation in all rooms: All rooms within the thermal building envelope must be directly or

indirectly (transferred air) ventilated with a sufficient volume flow rate. This also applies for

rooms which are not continuously used by persons provided that the mechanical ventilation of

these rooms does not involve disproportionately high expenditure.

o Excessively low relative indoor air humidity : If a relative indoor air humidity lower than 30 % is

shown in the PHPP for one or several months, effective countermeasures should be undertaken

(e.g. moisture recovery, air humidifiers, automatic control based on the demand or zone,

extended cascade ventilation, or monitoring of the actual relative air humidity with the option

of subsequent measures).

o Sound level: The ventilation system must not generate noise in living areas. Recommended

values for the sound level are ≤ 25 db(A): supply air rooms in residential buildings, and

bedrooms and recreational rooms in non-residential buildings ≤ 30 db(A): rooms in non-

residential buildings (except for bedrooms and recreational rooms) and extract air rooms in

residential buildings

o Draughts: The ventilation system must not cause uncomfortable draughts.

33

3.5 The Passive House Planning Package (PHPP)

The Passive House Planning Package (PHPP) (order here) contains everything necessary for designing a properly

functioning Passive House. The PHPP prepares an energy balance and calculates the annual energy demand of

the building based on the user input relating to the building's characteristics.

The main results provided by this software programme include:

o The annual heating demand [kWh/(m²a)] and maximum heating load [W/m²]

o Summer thermal comfort with active cooling: annual cooling demand [kWh/(m²a)] and maximum

cooling load [W/m²]

o Summer thermal comfort with passive cooling: frequency of overheating events [%]

o Annual primary energy demand for the whole building [kWh/(m²a)]

The PHPP consists of a software program and a printed manual. The manual not only elucidates the calculation

methods used in the PHPP but also explains other important key points in the construction of Passive Houses.

The actual PHPP program is based on Excel (or an equivalent spreadsheet software programme) with different

worksheets containing the respective inputs and calculations for various areas. Among other things, the PHPP

deals with the following aspects:

o Dimensioning of individual components (building component assemblies including U-value calculation,

quality of windows, shading, ventilation etc.) and their influence on the energy balance of the building in

winter as well as in summer

o Dimensioning of the heating load and cooling load

o Dimensioning of the mechanical systems for the entire building: heating, cooling, hot water provision

o Verification of the energy efficiency of the building concept in its entirety

34

The calculations are instantaneous, i.e. after changing an entry the user can immediately see the effect on the

energy balance of the building. This makes it possible to compare components of different qualities without

great effort and thus optimize the specific construction project - whether a new construction or a refurbishment

- in a step-by-step manner with reference to energy efficiency. Typical monthly climatic conditions for the

building location are selected as the underlying boundary conditions (particularly temperature and solar

radiation). Based on this, the PHPP calculates a monthly heating or cooling demand for the entered building. The

PHPP can thus be used for different climatic regions around the world.

All calculations in the PHPP are based strictly on the laws of physics. Wherever possible, specific algorithms

resort to current international standards. Generalisations are necessary in some places (e.g. global established

routines for shading), and sometimes deviations may also be necessary (due to the extremely low energy

demand of Passive Houses, e.g. for the asymptotic formula for the utilisation factor), while for some areas there

are no internationally relevant standards (e.g. with reference to dimensioning of ventilation systems). This

approach has resulted in an internationally reliable calculation tool with which the efficiency of a construction

project can be evaluated more accurately than with conventional calculation methods. (Read more about this in

the section PHPP - validated and proven in practice)

The PHPP forms the basis for quality assurance and certification of a building as a Passive House or an EnerPHit

retrofit. The results of the PHPP calculation are collated in a well-structured verification sheet. In addition to the

basic components of the PHPP already mentioned, various useful additions have also been made for the user's

benefit. For example, the simplified calculation method based on the German energy saving ordinance EnEV has

been integrated into the PHPP. Preparing an energy performance certificate for a project is facilitated by an

additional tool.

A section of the PHPP “Verification”-sheet with the results for a sample detached house built to the Passive

House Standard.

35

Figure 24 : flow chart on how the PHPP works

The PHPP can be used all over the world and is now available in several languages. Some of the translated

versions contain additional calculations based on regional standards (similar to the German EnEV) in order to

allow use as official verification of energy efficiency in the respective countries.

The first edition of the Passive House Planning Package (PHPP) was released in 1998 and has been continuously

further developed since then. New modules which were important for planning were added later on, including

advanced calculations for window parameters, shading, heating load and summer behaviour, cooling and

dehumidification demands, cooling load, ventilation for large objects and non-residential buildings, taking into

account of renewable energy sources and refurbishment of existing buildings (EnerPHit). The PHPP is

continuously being validated and expanded in line with measured values and new findings.

The new PHPP 9 (2015) was launched at the 19th International Passive House Conference in April 2015.

36

3.6 Boundary conditions for the PHPP calculation

When verifying the criteria using the Passive House Planning Package (PHPP), the following boundary conditions

must be fulfilled:

3.6.1 Zoning

The entire building envelope (e.g. a row of terraced houses or an apartment block or office building with several

thermally connected units) must be taken into account for calculation of the specific values. An overall

calculation can be used to provide evidence of this. If all zones have the same set temperature, then a weighted

average based on the TFA from individual PHPP calculations of several sub-zones may be used. Combination of

thermally separated buildings is not permissible. For the certification of refurbishments or extensions, the area

considered must contain at least one external wall, a roof surface and a floor slab or basement ceiling. Single

units inside a multi-storey building cannot be certified. Buildings which are adjacent to other buildings (e.g.

urban developments) must include at least one exterior wall, a roof area and a floor slab and/or basement

ceiling to be eligible for separate certification.

3.6.2 Calculaion method

The monthly method is used for the specific heating demand.

3.6.3 Internl heat gains

The PHPP contains standard values for internal heat gains in a range of utilization types. These are to be used

unless PHI has specified other values (e.g. national values). The use of the individually calculated internal heat

gains in PHPP is only permitted if it can be shown that actual utilisation will and must differ considerably from

the utilisation on which the standard values are based.

3.6.4 Internal moisture gains

Average value over all annual hours (also outside of the usage period): residential building: 100 g/(person*h)

non-residential building without significant moisture sources beyond moisture released by persons (e.g. office,

educational buildings etc.): 10 g/(Person*h) non-residential building with significant moisture sources beyond

moisture released by persons: plausible substantiated estimation based on the anticipated utilisation.

37

3.6.5 Occupancy rates

Residential buildings: standard occupancy rate in the PHPP; if the expected number of persons is significantly

higher than the standard occupancy rate, then it is recommended that the higher value should be used. Non-

residential buildings: Occupancy rates and periods of occupancy must be determined on a project-specific basis

and coordinated with the utilization profile.

3.6.6 Indoor design temperature

Heating, residential buildings: 20 °C without night setback, non-residential buildings: standard indoor

temperatures based on EN 12831 apply. For unspecified uses or deviating requirements, the indoor

temperature is to be determined on a project-specific basis. For intermittent heating (night setback), the indoor

design temperature may be decreased upon verification. Cooling and dehumidification: 25 °C for 12 g/kg

absolute indoor air humidity.

3.6.7 Climate data

Climate data sets (with a seven-digit ID number) approved by the Passive House Institute should be used. The

selected data set must be representative for the climate of the building's location. If an approved data set is not

yet available for the location of the building, then a new data set can be requested from an accredited Passive

House Building Certifier.

3.6.8 Average ventilation volumetric flow

Residential buildings: 20-30 m³/h per person in the household, but at least a 0.30-fold air change with reference

to the treated floor area multiplied by 2.5 m room height. Non-residential buildings: The average ventilation

volumetric flow must be determined for the specific project based on a fresh air demand of 15-30 m³/h per

person (higher volumetric flows are permitted in the case of use for sports etc. and if required by the applicable

mandatory requirements relating to labour laws). The different operation settings and times of the ventilation

system must be considered. Operating times for pre-ventilation and post-ventilation should be taken into

account when switching off the ventilation system. For residential and non-residential buildings, the mass flows

used must correspond with the actual adjusted values.

38

3.6.9 Domestic hot water demand

Residential buildings: 25 litres of 60 °C water per person per day unless PHI has specified other national values.

Non-residential buildings: the domestic hot water demand in litres of 60 °C water per person per day must be

separately determined for each specific project.

3.6.10 Balance boundary for electricity demand

All electricity uses that are within the thermal building envelope are taken into account in the energy balance.

Electricity uses near the building or on the premises that are outside of the thermal envelope are generally not

taken into account. By way of exception, the following electricity uses are taken into account even if they are

outside of the thermal envelope:

o Electricity for the generation and distribution of heating, domestic hot water and cooling as well as for

ventilation, provided that this supplies building parts situated within the thermal envelope.

o Elevators and escalators which are situated outside provided that these overcome the distance in height

caused by the building and serve as access to the building

o Computers and communication technology (server including UPS, telephone system etc.) including the

air conditioning necessary for these, to the extent they are used by the building's occupants.

o Household appliances such as washing machines, dryers, refrigerators , freezers if used by the building's

occupants themselves

o Intentional illumination of the interior by externally situated light sources.

39

3.7 Passive House Standard for Schools

The Passive House concept has been

undergoing a rapid expansion in the last few

years, also in the non-residential sector.

Administrative buildings, factory buildings,

community centers and many other buildings

have been realized. Some initial projects have

also been realized in the area of new school

construction and school modernization. The

systematically examined boundary conditions

for the construction of schools were published

in 2006 within the framework of the Protocol

Volume “Passive House Schools” in the

“Research Group for Cost-efficient Passive

Houses” [Feist 2006] . Experiences with initial

projects that have been realized were also

incorporated into this.

3.7.1 The Air Quality Issue

The pollution of the indoor air in schools consists mainly of the following:

o Outdoor air pollution

o Metabolic waste products of the occupants

o Emissions from building materials, furnishings and work

equipment (crafts, chemistry)

o Radon pollution

o Microorganisms (MVOC)

40

3.7.2 The Requirements

o Each modern school should have controlled ventilation which meets the criteria for acceptable indoor

air quality.

o In the interest of a justified investment or technical expenditure, the air flow rates of the school's

ventilation system should be based on health and educational objectives and not on the upper limits

of the comfort criteria. The result is: CO2 limit values between 1200 and 1500 ppm and designed air

flow rates between 15 and 20 m³/person/h (possibly more for a higher average age of the pupils).

With these reference values, the result is a significant improvement in the air quality in comparison with

the values usually obtained in Germany, Austria and

Switzerland today. Experience with the Passive Houses

already built also shows that the designed values should

not be reduced even further. For increased air quantities

attention would have to be paid to the resulting reduction

in the relative air humidity in winter. If the per person air

flow rates are projected as 15 to 20 m³/(h pers) in the given

interval, the primary objectives of indoor air quality will

certainly be achieved and the problem of low relative

humidity does not even arise.

In comparison with residential buildings and office buildings, the overall air flow rates and air change

rates which have to be planned are considerably higher during use due to the increased number of

persons present in schools.

o In the interest of justifiable operational costs, the ventilation systems in schools must be operated

periodically or according to demand. Preliminary purge phases or subsequent purging periods ensue

before and after use for hygiene reasons. The easiest solution is to use time control.

A direct result of the designed high air change rates is that the operating times of the ventilation system

have to be restricted to the periods of use or the air quantities should at least be greatly reduced

outside of these times, because otherwise there will be very high electricity consumption values even

for efficient systems – this differs fundamentally from home ventilation in which the designed air

quantities are near those required for basic ventilation needed on a permanent basis (with 0.25 h-1).

In schools, for basic ventilation planned with 2 h-1, there are several possibilities, the most efficient

being a one-hour preliminary purge phase with designed volumetric air flows, with which the necessary

”double” exchange of the air volume can be achieved. After that, regulation of the air quantities

according to demand should be strived for, on which the occupancy density, the CO2 content of the air

or other representative air quality indicator can be based.

Without any ventilation, the air quality is poor. The CO2 concentration can be easily measured; and is

correlated to other indoor pollution substances e.g. Radon. With a ventilation system, all pollution is

reduced to a hygienically satisfactory level (subjectively, visitors note that “it doesn't smell like a school

here at all”).

41

As shown by experience, it should be ensured that the technology used is robust and simple and, if

necessary, possible to operate manually (no “technological Christmas trees”). For intermittent operation

of the ventilation system, it is important that all system parts, especially the filters, are “run dry” before

switching off the air flows – this is achieved most easily by using the recirculation mode after the period

of use.

o Passive House schools should be designed so that besides the usual heating using supply air, it is also

possible to heat up the rooms to a comfortable level during the preliminary purge phase in the

morning. It is stated that heating classrooms using the supply air in schools is no problem because the

volumetric fresh air flow based on the useable area is very high. However, after the setback phase,

reheating to a comfortable level (particularly in relation to the radiation temperature asymmetry) is only

possible if the building's envelope surfaces have a high level of thermal protection. For schools this is

the decisive criterion.

Parametric studies with thermal simulation of school buildings show that under the given conditions the

level of thermal protection complying with the “residential Passive House Standard” is within the range

of optimum results. Nevertheless, for school buildings there is more scope than there is for residential

buildings, due to the many kinds of regulation possibilities and the high air changes available. Because

the buildings are generally comparatively large and compact, the designer is well-advised to approach

the optimum level by complying with the classic Passive House Standard while at the same keeping a

safety margin.

o The criteria given above can be met if, under the boundary conditions of use, the building envelope

and heat recovery are designed so that the annual heating demand according to the PHPP is less than

or equal to 15 kWh/(m²a) (based on the total net useable area).

A detailed analysis has confirmed the planning guidelines according to which some Passive House

schools had already been planned and built. This was by no means self-evident, as, due to the

completely different usage, this criterion is derived in a completely different way than the criterion

which applies to residential buildings.

Nevertheless, it is no coincident that this result is quantitatively comparable with that of the Passive

House residential building; the reason for this is that the temporal average values of the boundary

conditions (air quantities, internal heat sources, heat load) are very similar to those for residential use.

As shown by the examples of buildings which have already been built, applying these basic

recommendations and the components available on the market today, it is possible to realise Passive

House school buildings with various design concepts.

School refurbishment with Passive House components can be planned using the PHPP and that, except

for some clearly defined features, the same focal points had to be taken into consideration for these as

for residential or office buildings in the Passive House Standard.

An important boundary condition is the intermittent use with temporarily extremely high internal loads.

The temporal average value of the internal loads with 2.8 W/m² on average is not much more than the

42

values for residential use. Setback phases play an important role in school buildings. A tool is available

for determining the expected effective temperature reduction [PHPP 2007] .

In school buildings particular attention should be paid to specific use in summer. Sufficient shading,

night-time ventilation and high internal heat capacity are all imperatives. If it is not possible to meet one

of these requirements, equivalent compensation must be provided – this can be concrete core

temperature control or the use of adequate heat exchangers, for example.

For reheating after setback phases, the central heating generator must be able to provide a sufficiently

high output (in the range of 50 W/m² of heated useable area). The pre-heating phase must be regulated

via time control and internal temperature measurement.

Based on all previous experiences, the Passive House concept has proved to be just as successful for

schools, where it is particularly advantageous due to the ventilation system’s importance.

43

4 The Enerphit Procedure for the 27th Elementary School

4.1 General

Passive House school buildings are particularly interesting. Several school buildings have been realized using this

standard and experiences gained from their use are now available: The Passive House Standards allows for

energy savings of around 75% in comparison with average new school buildings - and of course there is no need

for an additional heating or cooling system. The additional investment costs are within reasonable limits. What

is important is the know-how - which can be obtained by every architect thanks to the “Passive House Schools”

Protocol Volume, funded by the Hessian Ministry of Economic Affairs.

While a comprehensive retrofit is always the best way to increase energy efficiency in existing buildings, it is

unfortunately not always possible. Often, financial or other challenges get in the way - the reality can be more

complex.

Figure 25 : Step-by-step approach of EnerPhit refurbishment plan

44

Each part of a building has its own life span. While the facade may be crumbling, the roof tiles may still be in

great shape. Perhaps the heating system is shot, yet it will be another 20 years before the windows need to be

replaced. Renovation measures can be time and resource intensive, which is why they are typically only carried

out when absolutely necessary. Once the facade has been newly insulated and painted, it will typically stay that

way, for better or worse, for the next generation or two. At the same time, energy efficiency measures for any

one part of the building are always most affordable when that part is already in need of renovation.

Step-by-step renovation is the natural result. One of the additional benefits of such an approach is that it gets

the most out of each building component so that the initial investment is taken advantage of to its fullest. Also,

renovation work is spread over a variety smaller measures is easier to finance.

If You Do It, Do It Right From The Start!

It is important to avoid missed opportunities by carrying out every retrofitting measure with an eye to quality

and energy efficiency. It is also essential to remember that when we retrofit, we are not just improving

aesthetics and reducing energy losses – we are also directly affecting a building’s moisture balance, air-flow,

surface temperatures and much more besides.

Planning Your Retrofit

When conducting a step-by-step deep retrofit, a well-thought out plan can help ensure that the integrity of the

building envelope throughout the renovation process. Improving airtightness, for example, without taking the

insulation and ventilation into account, may lead to otherwise avoidable moisture problems. Especially if many

years lie between various renovation steps, a plan covering present and future steps is essential.

45

Figure 26 : Examples of EnerPhit results

A master plan can be tailored to fit the needs of the building and/or its owners/users. For example, it could

specify the replacement of various components at various points in time or go facade by facade. However the

plan is composed, it should define the type, quality and order of measures to be taken. The reward for steps

carried out following an integrated plan: a future-proof, comfortable, sustainable building with consistently low

running costs.

46

4.2 The building envelope

The most important principle for energy efficient

construction is a continuous insulating envelope all

around the building (yellow thick line), which minimizes

heat losses like a warm coat.

In addition to the insulating envelope there should also

be an airtight layer (red line) as most insulation

materials are not airtight.

Preventing thermal bridges (circles) is essential – here

an individual planning method has to be developed,

according to the construction and used materials, in

order to achieve thermal bridge free design.

Independently of the construction, materials or building

technology, one rule is always applicable: both

insulation and airtight layers need to be continuous.

4.2.1 The opaque elements

Applying exterior wall insulation to an existing building when the plaster needs to be renewed can help reduce

the costs for the plaster significantly as plastering can be limited to rough filling where the old plaster is no

longer able to bear loads and needs to be chipped off.

There is no universal answer to the question whether a compound insulation system needs to be bonded to the

old plaster or even dowelled. Manufacturers are starting to offer strength tests for larger projects in order to

determine whether the old plaster is still able to bear loads. Additional dowelling may be dispensed with if such

guarantees are provided by manufacturers.

In our case we have added a 100mm external insulation layer (for example EPS 035) to all external walls of the

building (except from the eastern partition wall towards the neighboring building). The U-Value of the external

walls was improved as follows:

47


08ud Ext.wall_brick_eps





Plaster 0,872 20

Brick 0,523 90

Glass wool 0,041 50

Brick 0,523 90

Plaster 0,872 20

eps 0,035 100

Acrylic plaster 0,350 4


100% 37,4 cm

W/(m²K) U-Wert: 0,215 W/(m²K)


09ud Ext.wall_conc._eps





Plaster 0,872 20

Brick 0,523 60

Glass wool 0,041 50


Plaster 0,872 20

eps 0,035 100



70% 30,0% 55,4 cm

W/(m²K) U-Wert: 0,286 W/(m²K)

48

In the flat roof of the building we have added 100 mm of XPS 034

There is no need to put additional insulation on the sloped roof of the Auditorium. There is also no need to put

insulation on the ground floor slab, because the thermal bridges to the ground are not so important.


10ud Erker slab_eps


Ausrichtung des Bauteils 0,1 innen Rsi 0,10





plaster 0,872 20

eps 0,035 100



100% 32,4 cm

W/(m²K) U-Wert: 0,317 W/(m²K)


05ud Flat roof_eps





Plaster 0,870 10

Concrete slab 2,040 150

Light concrete 0,290 100

Cement mortar 1,400 20

Hydroinsulation 0,230 10

Extruded polystyrene 0,034 200

Gravel 2,000 50


100% 54,0 cm

W/(m²K) U-Wert: 0,151 W/(m²K)

49

4.2.2 Transparent Elements

In new buildings, as well as in old buildings that have not been modernized, windows constitute a weak point in

terms of thermal protection as their thermal transmittance (heat transfer coefficient, U-value) is generally much

poorer than that of the wall, roof or floor constructions. As a rule, windows of old buildings also have massive

leaks which lead to high heat losses and to an impairment of comfort due to drafts, and they can also cause

building damage. On the other hand, windows are essential in providing solar gains and thus reducing the

overall heating demand.

One of the objectives of carrying out modernizations is to provide a comfortable indoor temperature for the

occupants. Half our perception of warmth is from the radiant temperature of our surroundings and the other

half from the air temperature. It will feel cold next to internal surfaces that are cold even if the air temperature

is normal just from the lack of radiant heat. So for comfort it is important that cold internal surface

temperatures are avoided as well as draughts and temperature stratification in the room.

In this context it is important to limit the difference between the operative or perceived indoor temperature

and the temperature of the individual surfaces enclosing the room volume (walls, ceiling, floor or windows). As

long as the operative temperature also remains within the comfortable range unpleasant temperature

differences between surfaces and uncomfortable radiant heat effects are avoided. Limiting the temperature

difference also reduces the effect of cold air descending from cold surfaces producing draughts and cold feet.

In the relevant literature, e.g. [Feist 1998] , it is stated that as soon as the temperature of individual surfaces

that enclose the room volume does not exceed a limit of 4.2 K below the operative temperature of the room,

the unpleasant effects mentioned above can no longer occur.

Thus the comfort requirement is: θsi ≥ θop – 4,2 K.

If the operative indoor temperature θop is assumed to be 22°C and the external temperature θa is –16°C, for an

internal heat transfer resistance Rsi = 0,13 m²K/W, the result is the well-known Passive House comfort criterion

Uw,installed ≤ 0,85 W/(m²K) which was introduced more than a decade ago.

If it is not possible to achieve this value, a heat source must be provided underneath the window in order to

prevent uncomfortable cold air descent and radiant heat deprivation, and to achieve the desired level of

comfort.

The heat transfer coefficient for the installed window is determined based on the U-values of the glazing (Ug)

and the frame (Uf) as well as the thermal bridge loss coefficient of the glazing edge (Ψg), the connection of the

adjacent building components (ΨInstall) and the respective areas or lengths:

50

OrientationGlobal

RadiationShadings Dirty

Non vertical

radiationGlass area g-Value Reduction Factor Radiation Window area Uw Glass area

average

global

radiation

Standardwerte → kWh/(m²a) 0,75 0,95 0,85 m2 W/(m2K) m2 kWh/(m2a)

Nord 25 0,50 0,95 0,85 0,54 0,65 0,22 158,39 1,34 85,93 25

Ost 50 0,10 0,95 0,85 0,59 0,40 0,05 13,50 1,32 8,03 50

Süd 95 0,46 0,95 0,85 0,58 0,40 0,21 124,19 1,35 71,52 95

West 49 0,32 0,95 0,85 0,71 0,54 0,19 38,11 1,35 27,12 46

Horizontal 80 1,00 0,95 0,85 0,00 0,00 0,00 0,00 0,00 0,00 80

Summe bzw. Mittelwert über alle Fenster 0,53 0,21 334,18 1,34 192,60

All these values are required for the correct consideration of the heat losses of a window in the energy balance.

For the overall concept, not only the heat losses but also the solar gains through the windows are important.

Besides the orientation and shading of the windows, the total solar transmission factor of the glass and the

frame proportion also influence the solar gains. Since significant energy gains cannot be achieved through the

opaque frames, it is important to minimize the frame proportions (smaller facing widths, large windows, no

glazing bars, fewer glazing sections). The total solar transmission factor g refers to the proportion of incident

solar radiation which enters the building. If the g-value is 0,3 or 30%, for example, this means that 30% of the

solar radiation incident on the glass pane can reach the inside of the building. Modern standard triple-glazing

has g-values of around 50%. G-values of up to 60% are possible at moderate additional costs with the use of one

or more panes made of clear glass instead of float glass. The g-value is lower if there are special requirements in

terms of the robustness of the glass or fire protection regulations. This should be taken into consideration for

the energy balance at an early stage. In moderate climates, glass with lower g-values (solar protection glass)

should only be used if very high internal heat loads are expected.

In our building, windows are the main reason for the heat losses. So they have to be replaced with better,

thermal protected components. We have chosen the following values for the new components:

South oriented double-glazed windows with Ug=1,30 W/m2K, g-Value 0,40 and Uf=1,00 W/m2K

North oriented double-glazed windows with Ug=1,30 W/m2K, g-Value 0,60 and Uf=1,00 W/m2K

The east and west windows have the same values as the south oriented

All glass blocks will be replaced by double-glazed windows

Shading of the south-east-west windows will be improved by 75% during summer

51

The installation of the new windows will minimize the installation thermal bridges and improve their

airtightness.

The steel external doors of the building will also be

replaced by new with similar Uw values. The new doors

have to be double in order to improve the needed

airtightness.

52

4.3 The new Ventilation System with Heat Recovery

Ventilation with heat recovery is a central requirement for the operation of Passive Houses. The significant

reduction in ventilation heat losses as a result of the heat recovery makes it possible to both simplify and reduce

the size of the heating system, thereby reducing investment costs as well.

Ventilation with heat recovery plays an important role in energetic refurbishment as well. Significant cost and

energy savings due to the lower ventilation heat losses combined with the resulting good indoor air quality

make such ventilation not only more attractive, but necessary for energy efficient construction.

Next to climatic conditions and the required ventilation rate, a building’s ventilation heat losses mainly depend

on:

the heat recovery efficiency of the ventilation unit

the airtightness of the building (the free infiltration and exfiltration)

the forced infiltration and exfiltration caused by the volume flow balancing between exhaust and fresh

air

Beside the heat recovery of the ventilation unit and the airtightness of the building, the volume flow balancing

of exhaust air and fresh air also has an important influence on ventilation heat losses and, therefore, on the

energy balance of the whole building. Imbalances can be caused e.g. by improper commissioning of the

ventilation system or gradual clogging of the air filter.

In our case we have designed a simple ventilation system consisting of two main duct systems in each level, one

for the supply air into the north oriented classes and offices and one for the extract air from the south oriented

floors and sanitary rooms.

Figure 27 : Ground floor: the heat recovery unit is located in the former oil-tank room.

53

Figure 28 : 1st floor - Supply air goes to the classrooms, extract air comes from the corridors (the temperature

there is higher because of their south orientation) and the WC’s.

Figure 29 : 2nd floor - same design as in 1st floor.

The supply air volume is in general 18m3/h per person, so every classroom needs approximately 430m3/h. The

total capacity of the central unit is 5.000 m3/h. The heat recovery rate has to be >75%. There are certified units

with a rate of 85% in the market.

54

A ground heat exchanger, developed under the school yard, will

support the ventilation system and will adjust the air temperature

and humidity during the whole year. Ground-air heat exchangers

(also known as earth tubes) offer an innovative method of heating

and cooling a building and are often used on zero carbon /

Passivhaus buildings. The ventilation air is simply drawn through

underground pipes at a depth of 1.5m into the HRV, which pre-heats

the air in the winter and pre-cools the air in the summer. So the Heat

Recovery Rate will be as follows:

The Ventilation unit will have an automatic summer by-pass and an electrical heating registry. The unit will

operate 24h/day: 8 hours in full operation, 2 hours before the school opens at 77% and during the night at 40%.

The average ventilation volume will be 2.952 m3/h and the average air exchange will be 0,73 ach/h. The unit will

not operate during weekends and vacations. Preheating the air flow up to 38 Degrees Celsius will cover all the

heating demand of the building. It is proposed to use the existing conventional heating system of the building

every morning of a working day for an hour before the school opens. For the rest of the day the ventilation

system will cover the needs.

Selection of the ventilation unit with heat recovery

Location of the unit Inside the themal envelope

Heat recovery Humidity recovery Specific power Application range Frost protection

zur Lüftungsgeräte-Liste efficiency consumption required

Sortierung: WIE LISTE Unit hWRG hERV [Wh/m³] [m³/h]

Selection of unit 0,84 0,00 0,45 1300 - 5200 ja

Implementation of frost protection 1-Nein

Conductivity supply air duct Y W/(mK) 0,911 Temperature limit [°C] 2

Lenght of supply air duct m 5 Useful energy [kWh/a] 0

Conductivity extract air duct Y W/(mK) 0,911

Lenght of extract air duct m 5 Room temperature (°C) 20

Temperature of mechanical services room °C 20 Avg ambient temp. heat. period (°C) 12,9

(Enter only if the central unit is outside of the thermal envelope.) Avg ground temp (°C) 20,7

Effective heat recovery efficiency hWRG,eff 83,4%

Effective heat recovery efficiency subsoil heat exchanger

SHX efficiency h*EWÜ 85%

Heat recovery efficiency SHX hEWÜ 94%

0654vl03-LÜFTA - MAXK I3 6000 DC

1-Innerhalb therm.Hülle

Average air change rate calculation

Factors referenced to

Type of operation Daily operation times maximum Air flow rate Air change rate

h/d m³/h 1/h

Maximum 8,0 1,00 4680 1,16

Standard 2,0 0,77 3600 0,89

Basic 0,54 2520 0,62

Minimum 14,0 0,40 1872 0,46

Average air flow rate (m³/h) Average air change rate (1/h)

Average value 0,63 2952 0,73

55

During summer the ventilation rate will increase by 50%. Night ventilation

trough automatic opened windows will decrease the needs for cooling.

Heating Load PH= 16983 W

Heating Load according to Treated Floor Area PH / TFA = 13,4 W/m²

Input max. Supply air Temperature 38 °C °C °C

Max.Supply Air Temp. Jzu,Max 38 °C Supply air temperature without preheating Jzu,Min 19,7 19,7

For Comparison: Heating Load, transfelable by the Supply Air is PZuluft;Max= 17835 W specified : 14,1 W/m²

(ja/nein)(yes/no)

Heatable with supply air? ja yes

56

4.4 Heating and cooling

The existing heating system will be

used only for the pre-heating of the

building every day before the school

opens and after longer periods, when

the school is closed. This will decrease

the gas consumption by 80%. In order

to improve the performance of the

system, the pipe system has to be well

insulated.

The building will need 4.500 KWh/a for

heating.

For the summer situation the split units that exist, will cover the needs of the building. It is proposed to put

these units on the corridors of each Level and the ventilation system will supply the fresh air in all rooms. 20Kw

of air-conditioning power will cover the whole building. The building will need 11.500 KWh/a for cooling.

57

4.5 The overall results of the passive house retrofit

With the implementation of the above described specifications and according to the calculations with the

Passive House Planning Package PHPP ver. 9,1/2015 the new energy balances of the building will be as

following:

4.5.1 The winter situation (monthly method)

Figure 30 : Winter energy balance from PHPP after renovation

58

The losses of the external walls (light blue), the windows (yellow) and the airtightness on the left column are

extremely decreased. The losses are more balanced now. There are no losses to the ground. On the other hand

the solar gains (yellow) on the right column are still not big enough. A further improvement for the solar gains

could be to install horizontal windows on the existing south oriented sloped roof. The heating energy demand is

decreased by 85%.

4.5.2 The summer situation (monthly method)

Figure 31 : Summer energy balance from PHPP after renovation

59

The additional ventilation with the by-pass control and the night ventilation through the windows is very

important for reducing the risk of overheating. The mechanical ventilation should be decreased during the

summer period by 50% and the night ventilation should add 0,50 ACH/h.

Below is the new energy balance of the building according to PHPP calculations:

60

According to these results the building is a Passive House Plus Building. The heating demand is now

4KWh/m2a, decreased by 93% and the cooling demand is 9KWh/m2a,

EnerPHit-VerificationFoto oder Zeichnung Building:

Street:

Postcode / City:

Province/Country

Building type:

Climate data set: ud---02-Athinai-Piraeus

Climate zone: 5: Warm Standorthöhe: 50 m

Home owner / Client:

Street:

Postcode/City:

Province/Country

Architecture: Mechanical system:

Street: Street:

Postcode/City Postcode / City:

Province/Country Province/Country

Energy consultancy: Certification:

Street: Street:

Postcode / City: 15234 Postcode / City:

Province/Country Province/Country

Year of construction: 1987 Interior temperature winter [°C] 20,0 Interior temp. summer [°C] 25,0

No. of dwelling units: 1 Internal heat gains (IHG) heating case [W/m2]: 2,8 IHG cooling case [W/m²]: 2,8

No. of occupants: 260,0 Specific capacity [Wh/K per m² TFA]: 204 Mechanical cooling: x

Specific building demands with reference to the treated floor area

Treated floor area m² 1263,8 Criteria Fullfilled?2

Space heating Heating demand kWh/(m²a) 4 ≤ 15 -

Heating load W/m² 13 ≤ - -

Space cooling Cooling and dehumid. demand kWh/(m²a) 9 ≤ 15 16

Cooling load W/m² 12 ≤ - 11

Frequency of overheating (> 25 °C) % - ≤ - -

Frequency excess humidity (> 12 g/kg) % 0 ≤ 10 ja

Airtightness Pressurization test result n50 1/h 1,0 ≤ 1,0 ja

PE-Demand kWh/(m²a) 76 ≤ - -

PER demand kWh/(m²a) 25 ≤ 45 30

kWh/(m²a) 57 ≥ 60 36


EnerPHit Plus? ja

Task Name Surname Signature

1-Projektierer

Ausgestellt am Ort

09/05/15

Non-renewable primary energy

(PE)

Primary Energy

Renewable Generation of renewable

energy

Stefan

I confirm that the values given herein have been determined following the PHPP methodology and based on the

characteristic values of the building.The PHPP calculations are attached to this application.

ja

GR-GriechenlandAttiki

Iraklidon 15B

Chalandri

Attiki

27th Elementary School of Piraeus

Attiki

Municipality of Piraeus

GR-Griechenland

School

Stefanos Pallantzas

ja

ja

Alternative

criteria

GR-Griechenland

Pallantzas

CEPH Designer - Civil Engineer Athens

61

decreased by 82%. These results cover the passive house criteria for our

climatic region (<15 KWh/m2a for heating or cooling).

The loads for heating and cooling are 13W/m2 and 12W/m2, 10

times lower than these of the conventional buildings.

The Primary Energy Demand (PE) is 76KWh/m2a, fulfills the 120KWh/m2a criteria. Also following the new PER

criteria of Primary Renewable Energy the criteria are fulfilled.

Furthermore, if we install a 160m2 Photovoltaic System on the south roofs of the building, the building will

produce on average over 45.000 Kwh of electricity every year, a factor which will make the building a PLUS

passive house, a building that produces the energy it needs.

Name of system System 1 System 2 Anlage 3 Anlage 4 Anlage 5 PV-Referenzanlage

Location: Selection in 'Areas' worksheet 3-SLOPED_ROOF 54-2f_ROOF_SLAB

Size of selected area 126,4 505,9 m²

Deviation from North 180 0 °

Angle of inclination from horizontal 13 0 °

Alternative data input: Deviation from North °

Alternative data input: Angle of inclination from the horizontal °

Information from the module data sheet

Technology 4-Mono-Si 5-Poly-Si 5-Poly-Si 5-Poly-Si 5-Poly-Si 4-Mono-Si

Nominal current IMPP0 7,71 7,71 7,71 A

Nominal voltage UMPP0 30,50 30,50 30,50 V

Nominal power Pn 235 235 0 0 0 235 Wp

Temperature coefficient short-circuit current a 0,040 0,040 0,040 %/K

Temperature coefficient open-circuit voltage b -0,340 -0,340 -0,340 %/K

Module dimensions: Height 1,658 1,658 1,658 m

Module dimensions: Width 0,994 0,994 0,994 m

1,6 Modulfläche [m²]

Further specifications

Number of modules nM 50 50 0,0

Height of module array 1,0 1,0 m

Height of horizon hHori 0,0 0,0 m

Horizontal distance aHori 15,0 15,0 m

Additional reduction factor shading rso

Efficiency of the inverter hWR 95% 195% 95%

Results

Area of module field 82,4 82,4 0,0 0,0 0,0 0,0 m²

Free area on the selected building element 44,0 423,5 m²

Allocation to building element 65% 16%

Annual losses due to shading 0 0 kWh

Summe

Annual electricity yield of the inverter, absolute 15704 29909 45613 kWh/a

Related to ground area 19,5 37,2 57 kWh/m²AGrund*a

Specific PE factor (non-renewable primary energy) 0,30 0,11 kWhprim_ne/kWhEnd

Specific CO2-equivalent emisson value of system 44,5 20,9 g/kWh

CO2 equivalent emissions according to 1-CO2 factors GEMIS 4.6 (Germany) 2104,4 3110,5 5214,9 kg/a

62

5 Comparison of PASSIVE HOUSES Step-by-Step Approach & KENAK

5.1 Step-By-Step Enerphit Renovation actions of the 27th Elementary

School of Piraeus

In our case we propose a 3-step renovation of the building according to the most efficient and cost effective

way:

5.1.1 1st step: Insulation of the building envelope

Our calculations with the PHPP show that the main losses of the building, especially during winter are from the

external walls and the roof. By putting 100mm of external insulation. for example EPS insulation 035 on every

external wall and by adding 100mm of additional insulation on the flat roof and the erker slabs, we have the

following results in energy consumption :

The heating demand will decrease from 56 to 29KWh/m2a, the cooling demand will decrease from 49 to 40

KWh/m2a and the Primary Energy Demand will decrease from 192 to 133 KWh/m2a.

This means :

48% decrease of heating demand during winter.

18% decrease of ccooling demand during the summer days.

30% decrease of primary energy demand during the whole year.

The total cost of this 1st step is estimated to be 95.000 euros (1853 m2 of external surface * 50euros/m2).

63

5.1.2 2nd step: New windows and doors, Additional Shading, Night

Ventilation schedule

The second step of the renovation has to be the replacement of all the windows and doors of the building, the

design of better shading to the south, the increase of the air tightness of the building and a new night

ventilation plan.

The results after these steps are:


KWh/m2a and the Primary Energy Demand will decrease from 133 to 76 KWh/m2a.

This means :

45% decrease of heating demand during winter from 1st step and 71% from existing building

55% decrease of cooling demand during the summer days from 1st step and 63% from existing building

43% decrease of primary energy demand during the whole year from 1st step and 60% from existing

building

The total cost of this 2nd step is estimated to be 85.000 euros for the windows and doors. (335 m2 of surface *

250 euros/m2, together with increase of airtightness).

The new shading system to the south is estimated to cost 25.000 euros. No costs are for the night ventilation.





Space coolingCooling and dehumidification demand kWh/(m²a) 19 ≤ 15 16




Airtightness Pressurization test result n50 1/h 3,0 ≤ 1,0 nein

PE-Demand kWh/(m²a) 76 ≤ 123,970558 ja

PER demand kWh/(m²a) 51 ≤ - -

kWh/(m²a) 0 ≥ - -



(PE)

Primary Energy


energy

-

nein

nein

Alternative

criteria

64

5.1.3 3rd step: Mechanical Ventilation with heat recovery and PV panels

on the roof

The final step of the renovation will cover the building systems and the use of Renewable Sources. The

mechanical ventilation with heat recovery and ground heat exchanger, as described in our primary study will be

installed.

Two PV systems , one on the sloped roof and one on the flat roof will produce over 45.000 Kwh every year. This

means 57KWh/m2a of RES will cover nearly 70% of the needs of the school. This system can be increased in the

future in order to make the school energy-neutral.

Finally the airtightness of the building will be reduced to 1ACH, by closing all possible gaps in the building

envelope and creating a continuous airtight layer on the inside surface of the building.

65

The results after these steps are:


KWh/m2a and the Primary Energy Demand (nonrenewable) will decrease from 76 to 25 KWh/m2a.

This means:

75% decrease of heating demand during winter from 2nd step and 93% from existing building

50% decrease of cooling demand during the summer days from 2nd step and 82% from existing building

67% decrease of primary energy demand during the whole year from 2nd step and 87% from existing

building.

The costs of the ventilation system are estimated as follows:

The Ventilation unit with preheating and summer-bypass and regulation 30.000 euros

The ground heat exchanger 15.000 euros

The Duct system 20.000 euros.

The cost of the PV system is estimated 20.000 Euros.

The costs of the finalization of the airtightness layer is estimated 15.000 euros.





Space coolingCooling and dehumidification demand kWh/(m²a) 9 ≤ 15 16




Airtightness Pressurization test result n50 1/h 1,0 ≤ 1,0 ja

PE-Demand kWh/(m²a) 76 ≤ - -

PER demand kWh/(m²a) 25 ≤ 45 30

kWh/(m²a) 57 ≥ 60 36


ja

ja

Alternative

criteria

ja


(PE)

Primary Energy


energy

66

5.2 Economics of Step-by-step approach by ENERPHIT

5.2.1 Economy and financing of efficiency according to the EnerPHit

standard

The economic assessment of buildings has to be based on life cycle costs. From the beginning this was the

concept of the Passive House, and the concept of cost optimality (“cost optimal level”) based on life cycle costs

has become a major issue in the Energy Performance of Buildings Directive (EPBD) of the European Union.

There are many methodological frameworks that fit more or less in this scheme: not all methods though fulfill

the requirement of reflecting the whole economic picture. Furthermore, boundary conditions are as important

as the method. Inadequate methods, different assumptions or boundary conditions are the most important

cause of extremely different results of empiric studies. The main sources of major distortions are assignment of

costs that are not related to energy efficiency, underestimation of life expectancy, failure to consider residual

values at the end of the calculation period, unrealistic assumptions on energy price increases, unreliable design

and quality of measures, inadequate expectations on return and related discount rates, and lock-in effects. The

net effect of these influences is usually that estimated economic energy savings result much lower than they

are, which turns out to be a strong barrier for the implementation of energy efficiency.

Economic Assessment of Energy Efficiency

The overall longevity of buildings implies that short payback periods cannot be expected; they are not good

indicators since they are neither related to the investment period length, nor to the relevance of the measures.

Instead, the whole life cycle as well as the interests must be regarded. This view is implemented in dynamical

methods based on present values. In theory, economic activities aim at profits which can only be evaluated in

comparison with alternatives. The alternative to an energy efficiency investment is the investment in other

assets or a bank deposit which yields interests. Another option would be to avoid the loan, thus saving interests

on debt.

Costs

Expenditures are made to achieve benefits. However, these investments have follow-up operational costs, e.g.

for maintenance and energy. The end of the building useful life in most cases is not planned as it will happen in

the far future. It is not even known whether costs or revenues will occur at demolition. Therefore, life cycle

costs of buildings mostly include the investment cost and estimated running costs, referring to the same point in

time. Life cycle costs are the total costs over the building life time, discounted according to the year when they

occur.

67

Investment theory

Benefits become market goods, and investments are made to achieve revenues from benefits sold on the

market. The goal of the investor is to achieve an economic advantage: an investment should be at least as

attractive as its alternatives that are available on the capital market. Surpluses are gains, when they are higher

than those for an alternative, economically comparable, capital asset. The benchmark is the return for

comparable assets (classification: risk; a subjective assessment can involve non-economic factors too). In a

perfect capital market there is only one interest rate (= price of capital). Investments should be profitable on the

long run.

Figure 32: Cash value (or present value) of periodic revenues depending on number of periods and interest

rates. High interest rates depreciate the value of the revenues and thus the market capitalisation.

The present value of revenue (or any cash flow) is the amount needed now to yield the same revenue from the

bank, including interests. The present value of a payment is the amount you need ‘now’ to pay ‘later’, when the

expenditure occurs. Since present values refer to the same point in time, all receipts and expenditures become

comparable, but the result depends on the discount rate. Discount rates are crucial: High expected rates of

return depreciate later revenues, thus the upfront investments. Therefore, the choice of an adequate interest

rate is important. For effective economic assessments, it is useful to do the calculation based on real prices and

interest rates, while inflation - which does not affect the economic result - is taken out from the calculation.

68

The net present value (NPV) is the sum of all present values: costs (or payments, e.g. the investment) are

negative, and revenues are positive. The NPV is the total gain of the investment, when all lifetime costs and

revenues are taken into account. Therefore, a positive or non-negative NPV means that the investment is

economic. As long as capital (incl. debt) is available, it is economically profitable to make any investment up to a

NPV of 0.

Besides the net present value, other target values and methods are used. While our main focus is on the

investment’s object, investors may have a different point of view (equity perspective). Instruments like the

Discounted Cash Flow (DCF) (based on the same discounting principle of the present value method) or the

Visualization of Financial Impli-cations (VoFI's) methods are used to optimise financing (equity or debt capital) or

taxation aspects. In VoFI's all in- and out-payments (i.e. original payments that are not discounted) imputable to

an investment are reported for individual periods. This includes all funding as well as interests and tax

payments; the method is especially used for liquidity planning.

Methods, boundary conditions, possible distortions

As long as boundary conditions and perspectives are the same, the above mentioned dynamical methods lead to

the same economic result. But it turns out that this result is very sensitive to the assumptions about boundary

conditions. Therefore, it is very important to survey boundary data very carefully. Special attention has to be

paid to all estimations of future data, in case of doubt sensitivity analyses shed light on the possible range of

results. Otherwise, the economic assessment may be severely distorted. In particular, it is necessary to verify:

Figure 33 : Residual values for calculation period of 20 years

69

Figure 34 : The economical effect of bringing forward the exchange of windows (2013)with Passive House

windows

Figure 35: Medium quality is a barrier to future energy efficiency investments. Here: Wall insulation, profit

depending on insulation thickness equivalent before refurbishment

70

• Proper attribution of investment costs: only (additional) investments that are imputable to energy

efficiency may be accounted for in the economic analysis. Although this seems obvious, the calculation including

all the measures’ costs which are often many times higher than the additional investment costs for energy

efficiency, is very often the reason for a wrong economic assessment result.

• Life cycle of the measures: make sure that revenues (e.g. saved energy’s costs) yielded after the end of

the pay back time are not forgotten. Total life cycle results are what counts.

• When calculation periods are longer than the life cycle of the measure or the component, replacement

costs must be considered. However, when they are shorter (which is often the case for buildings), residual

values must be regarded at the end of the calculation period – instead they are often forgotten. Depending on

the lifetime span, the calculation period and the discount rate, residual values can easily be up to 30% or more

of the original investment.

• Interest (discount) rates: often the expected rates of return are inadequately high (see next chapter)

• Future energy prices and price increase: Assumptions on constant rate of growth may lead to

unrealistically high energy prices for long calculation periods.

• Point in time of the measure: does the measure fit within the normal renewal cycle, or is there a

residual depreciation of the component? In the latter case, the residual value of the basic investment has to be

added to the extra energy efficiency investment. This proves that undertaking retrofit based on potential energy

savings is not an effective strategy

• The starting point of energy efficiency interventions: medium quality reduces energy demand, but also

possible energy savings later, thus the potential revenues of an energy efficiency investment. Future

amendments to improve their quality are very improbable because they will not pay back, thus impeding future

sustainable developments. Therefore, “when you do it, do it right”.

Risk and return

One of the most prominent distortions results from the frequent expectation of high returns. The expected

rates of return are the calculatory interest rates (or discount rates) in the dynamic economic assessment. We

have seen that the present value of future payments decreases with high interest rates and depreciates the

investment. But high interest rates are coupled with high risks. On the capital market, it is not possible to earn

high interests with risk free investments. However, energy saving investments are risk free or even risk reducing

- as long as the building they belong to are not in question. Which buildings should be kept in the stock and

upgraded is a decision concerning the real estate portfolio management. However, once the decision to proceed

with the retrofit has been made, it is always advantageous to include the energy efficiency investment, reducing

the risk of higher energy prices that might affect the market. Since risky investments with the chance of higher

ROI's are not comparable with energy efficiency investments, they are not eligible alternative assets to measure

71

the economic success. For low risk investments, however, a “risk premium” cannot be expected. They can be

financed by credits though, and they should when equity is expected to yield high rates of return.

Figure 36: Risk and return. Risk premium on the capital market is the additional expected rate of return

attributed to the risk.

Cost optimality

The European EPBD aims at the implementation of “nearly zero energy buildings”. The economic criterion

beyond the directive is the reference to life cycle costs for both new and retrofitted buildings. Economy is

assessed solely on the basis of life cycle costs. The minimum requirements to be defined by the member states

have to meet the 'cost optimal level' which is supposed to move in the direction of higher efficiency after the

effects of learning and scale; member states are expected to support this development. It has been shown that

Passive House components allow achieving profitable levels and given PH low energy demand, the basis for the

supply with renewables from nearby. This is the background of “Passive House Regions” [PassREg].

72

Figure 37: Life cycle costs for external insulation (refurbishment) depending on insulation thickness. The cost

optimal range is in the range of EnerPHit Standard

It is important to tap the full potential of profit -at least up to the cost optimal level. Otherwise it would become

very difficult to mobilise the rest of the potential, as measures’ minimum costs would be too high to be paid

back within the life time. The cost optimality curves are usually very flat; therefore very low additional efficiency

investments fall within the uncertainty range with respect to cost optimality. Never the-less they are a risk

reducing and cheap insurance against energy shortage and price rises. It is important to note that, as discussed

before, the rate of return is an interest rate for risk free investments, and, obviously, is not the target value for

optimisation.

Even Passive House components for renovation projects are economically optimal, when evaluated on the basis

of correct life cycle costs (see ). For such renovations, PHI has established the “EnerPHit” label. Depending

mainly on the building conditions before refurbishment, there might be a high economic gain leading to an

extremely good rate of return with a low risk investment. It is hard to find anything that could provide a similar

economic advantage.

73

The Step by Step procedure

The EuroPhit project - supported by the EU within the Intelligent Energy Europe framework, focuses on step by

step retrofit. This part of the renovation market is often not perceived, although it has a considerable share.

Step by step retrofit is not an exception but normal practice: renovations are done when there is a cause for

that, and we have seen that this is reasonable also from the economical point of view. Furthermore, owners

tend to avoid big renovations when possible. It is also true that partial renovation cannot be adjusted or

completed later, without extra effort that would not pay back. The opportunity can be taken or not.

EuroPhit will show how high quality - guaranteed by integrated design, trained workmanship, and collaboration

of all actors in built projects all over Europe -, will lead to reliable performance, including the achievement of

efficiency goals and economic results, even for well-planned step by step retrofit. For correct economic analysis,

it is crucial that the planned energy savings are realized, as they define the revenues. Step by step renovations

differ, in that each step should be completed in view of the final high efficiency result. From the economic point

of view, it is advantageous when all components are upgraded at the end of their lifetime. However, analysis

has to take into account the extra costs for any work to be repeated during following renovation steps, and

compare them with the additional costs of doing the next step’s interventions in advance.

Financing and effective incentives

All investments have to be financed. In the building sector, large capitals are needed, which in many cases

cannot be covered by equity. Therefore, often credits are needed, with more or less attractive boundary

conditions and required collaterals. On the other hand, credits required for partial renovations are smaller, and

seem not be particularly relevant for banks, so they don't offer attractive conditions. The picture might change if

a long term plan for step by step retrofit would be set up, including high quality design and coordination of the

whole process. In this case, the owners can offer excellent collaterals and the credit represents a low risk for the

financing institution, thus it can be awarded at good conditions and/or good ratings.

Funding and incentives help overcome financial barriers. When the investment is not economical on the basis of

life cycle costs (e.g. in markets that are new to energy efficiency), a subsidy can make it economically feasible.

This situation can be used to influence the market in an effective way: Incentives should aim at supporting an

effective and sustainable reduction of energy demand and carbon emissions, and to guarantee a good

performance by quality assurance requirements.

If energy saving investments are already economically feasible, funding should avoid keeping them expensive.

Instead, financial aids should focus on:

• improving liquidity and reducing the financial burden. This can be achieved through direct financial

support, but also special credit lines with low interest rates (especially in the first years)

• supporting collaterals to facilitate access to attractive bank credits

74

• binding financial support to quality assured design to realize the expected performance and guarantee

damage-free construction and long lifetime measures

• achieving very high energy efficiency, because the next renovation will only happen after many years. In

this respect, medium quality would hinder the necessary reduction of energy demand and emissions and cause

a “lock in” effect.

• An interesting example is offered by the German KfW credits (www.kfw.de). The low interest loans for

energy efficient new and retrofit buildings are coupled with direct subsidies, which are higher for better energy

efficiency.

• Many German regions provide extra subsidies in support of energy efficiency. For the Hanover region

e.g., it could be proved that every Euro granted by the proKlima-Fonds:

• generates a total investment of 16 €, while the additional investment for additional efficiency is only 2 €

(but double the value of the incentive) - creates added value of 7 € - generates a local labour equivalent to 3 €.

Figure 38: Total cost advantage for Passive Houses with and without funding by the KfW. Cumulated annual

costs.

75

While on the long run the saved energy costs are dominant for the result, the low interest loan diminishes costs

in the first years and results in better liquidity

Figure 39: Added value created by local funding of energy efficiency [AkkP42]

Therefore, funding is not only beneficial for the investor and the building owner, but also for the community.

This is because it does not just generate otherwise unneeded labour, but also is multiplied by private

investments which create real added value. This is also true when the incentive is not necessary for the

profitability of the investment, but “only” for better boundary conditions of financing, or for raising awareness.

Furthermore, this process implies other positive economic effects that are not included in the above results,

especially the better quality and longer lifetime of the buildings and all the effects of learning and scale.

76

5.2.2 Example of incentive programs for retrofits: the KfW in Germany

In Germany the KfW Bank handles incentive programs on behalf of the Federal Ministry of Transport, Building

and Urban Development. The programs for energy-efficient construction and refurbishment receive favorable

terms through German federal budget funds to provide financial incentives for more energy efficiency in the

housing sector. Recent studies show that in Germany, energetic refurbishment of buildings is a win-win situation

for the home owners, the environment, the economy and the federal budget. The effects of the supported

energy efficiency measures have been evaluated since 2006. The current and previous evaluations and studies

on the economic impacts are available on the website of the KfW Bank, in German.

The refurbishment of existing buildings to high energy standards significantly contributes to the reduction of

energy demand and the lowering of greenhouse gas emissions. It also achieves enormous savings in heating

costs. The additional demand in the construction sector has a positive effect on employment, which benefits

SMEs in particular. In 2011, KfW committed loans and grants of EUR 2,9 billion for the retrofit of residential

housing, this induced investments of 3,9 billion, and secured employment for 52.000 people. For each Euro

spent from the budget to promote the retrofit of existing buildings and the construction of energy-efficient new

builds, the German Federal Government received at least 3 Euros in tax income and savings, according to a

study by Forschungszentrum Jülich (STE Report, also see Page 7, Table 2 of the study Energieeffizient Bauen und

Sanieren.

The impacts of this program are noticeable. Incentives for energy efficient new builds and retrofits trigger high

turnover. If the sales resulting from additional demand for wholesale service items (such as demand for

insulation materials, heating furnaces, etc) are included with direct sales, for 2011 alone, the program resulted

in a total turnover volume of EUR 27 billion for 262.000 homes (181.000 retrofits and 81.000 new builds).

Energy retrofits are, for the most part, cost-effective when incorporated as part of the retrofit cycle, in other

words with already planned modernization measures. The promoted energy efficiency measures also have a

noticeable impact on the labor market in that they trigger considerable employment effects. In 2011, for energy

efficiency investments in the building sector overall, about 251.000 jobs were secured or created. The

construction industry accounts for nearly three quarters of the direct employment effects. This also triggers

indirect employment effects through the demand for inputs such as heating furnaces or insulation material in

other industries. Due to the strong representation of SMEs in the construction industry, SMEs particularly

benefit from the employment effects: 83 % of the overall employment effects occur in SMEs.

Macroeconomic analysis of the KfW’s EBS programs demonstrates that the continuation of these programs

would provide the German economy with long-term growth impulses. Significant expansion of the programs,

guaranteeing that the targets set in the context of the Federal government’s energy revolution strategy are met,

would substantially increase these effects (see also Energieeffizient Bauen und Sanieren). In view of the very

positive results of the KfW incentive programs on retrofitting in Germany, the implementation of similar

programs in other countries is recommended. The ELENA facility provided by EIB and KfW may be used to

refinance such programs for the public sector. See European Commission and European Investment Bank launch

European Local Energy Assistance (ELENA) facility.

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5.2.3 Measurements for checking consumption – "Minimal Monitoring"

A key issue that often arises with reference to realized innovative, energy efficient buildings and retrofits is

whether the planned low energy demand is actually achieved in a measurable way. The aim is to determine the

total consumption of a building using simple means and with as little effort as possible, and to be able to

differentiate between the areas for heating, hot water and electricity use as far as possible. This question has

nothing to do with significantly more extensive scientific analyses.

In this connection, the term “minimal monitoring” should be understood to mean “an efficiency review of a

building regarding its energy consumption using minimal effort”.

The question that arises is: what is needed to achieve this objective and what is unnecessary? What is the extent

of the conclusions of such an investigation and what exactly can or cannot be said about that building? The

measurement e.g. of the total gas consumption is very easy, but determining the share for heating without hot

water generation, distribution and conversion losses requires much more effort. The solutions presented here

are based on at least monthly meter readings taking place manually without the use of a complicated data

acquisition system. They are intended to enable an initial analysis of the building without major technical effort.

Summary of minimal monitoring

The most important points regarding minimal monitoring are summarized below:

Monthly meter readings of all essential meters (electricity, gas, district heat) or specification of the

procured quantities of firewood, wood pellets or crude oil.

An additional heat meter is necessary in case of a solar heating system.

Distribution and conversion losses are taken into account as a simplified overall value.

The energy consumption for hot water generation is calculated from the consumption data of the

summer months. An overall adjustment can be made here additionally in order to take into account the

summer/winter fluctuation in consumption of hot water.

Temperature adjustment of the consumption values can be carried out optionally if there are variations

from the calculated value (standard 20 °C) and these are known.

The total annual electricity consumption (domestic electricity and electricity for technology/auxiliary

use) must be accounted (PV electricity must be taken into account using a separate feed-in meter).

Despite the limited accuracy of this method for estimation of heat consumption and disregarding of the various

influencing factors, this provides a valuable overall picture for an initial assessment of the building.

Calculation of the primary energy use is reliable due to the use of the total unadjusted final energy consumption

and can be used successfully for checking compliance with the PE limit value.

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5.2.4 Overall costs and savings of the renovation based on Enerphit

The total costs of the renovation are as follows:

Euros in total Euros / m2 (building area 1500m2)

1st step 95.000 62,91

2nd step 110.000 72,85

3rd step 100.000 66,22

TOTAL 305.000 201,98

Table 13 :total cost of renovations based in Enerphit

The total savings in energy will start from the first year of the retrofit procedure. The savings will grow as

follows:

Saved KWh total Saved euros

(0,15euro/KWh)

Saved euros /m2

1st year 28.678 4.301,74 2,85

2nd year 56.384 8.457,67 5,60

3rd year 81.174 12.176,13 8,06

TOTAL 166.236 24.935,40 16,51

Table 14 : total savings in energy based in enerphit

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5.3 Retrofit Plans by KENAK

The retrofit Plan that are proposed in the KENAK methodology that was followed are described in detail in

Deliverable D.7 of the present study.

In more detail, as long as it concerns the 27th Elementary School of Piraeus, three scenario of retrofit are

proposed:

- Scenario 1 : Insulation of the Vertical Structural items

o Results

Energy Class : C

Energy Efficient according to KENAK : no

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- Scenario 2 : Scenario 1 & replacement of the windows with synthetic ones, with double glassing

o Results

Energy Class : C

Energy Efficient according to KENAK : no

- Scenario 3 : Scenario 2 & PV panels for electricity creation

o Results

Energy Class : B+

Energy Efficient according to KENAK : yes

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5.4 Comparison between KENAK approach and ENERPHIT approach

In the present section, a comparison between the results of KENAK approach and the Enerphit approach is

given, concerning:

Primary Energy

Thermal Energy

Cooling Energy

Lighting Energy (only for the case of KENAK)

Based on this comparison, the results of Enerphit approach for the case for 27th School of Pireas, are illustrating

a great difference and advantage of the Passive House Standard in order to target the NZEB !

In addition, the Enerphit methodology (step by step) is an excellent tool for estimating the proper procedure for

renovating a school, based on the time-wise retrofit plan, following a financing plan that a Municipality in

Greece can comply.

In the following table, analytical comparison is given.

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KENAK EuroPhit

Kwh/m2 * a Investment Cost

in Euros

Yearly Energy

Savings

kwh/m2*a

Kwh/m2 * a Investment

Cost in Euros

Yearly Energy

Savings

kwh/m2*a

Initial Status Thermal : 30

Cooling : 13

Lighting : 60

Primary : 103

Thermal : 56

Cooling : 49

Primary : 192

Scenario 1 Thermal : 29

Cooling : 13

Lighting : 60

Primary :101

33.593 1,1


Cooling : 12

Lighting : 60

Primary :97

91.924 5,6


Cooling : 12

Lighting : 60

Primary : 43

126.924 59,9

Step 1 Thermal : 29

Cooling : 31

Primary : 133

95.000 22,7

Step 1 & 2 Thermal : 16

Cooling : 19

Primary : 76

205.000 44,6

Step 1 & 2 & 3 Thermal : 4

Cooling : 9

Primary : 25

305.000 64,3

Table 15 : Comparison Results for KENAK & ENERPHIT approaches

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6 Conclusion

The Passive House is the world‘s leading standard in energy efficient design. It started out as a construction

concept for residential buildings in Central Europe. Today, the Passive House Standard can be implemented in

all types of buildings almost anywhere in the world. The demand for Passive Houses as well as information on

and experience with Passive Houses has been increasing at an enormous pace, reflecting the trend-setting

developments in this field.

This study has shown that by applying these basic recommendations and the components available on the

market today, it is possible to realize Passive House school buildings with various design concepts.

Retrofit of school buildings to the passive house standard can be planned using the PHPP and that, except for

some clearly defined features, the same focal points had to be taken into consideration for these as for

residential or office buildings in the Passive House Standard.

An important boundary condition is the intermittent use with temporarily extremely high internal loads. The

temporal average value of the internal loads with 2,8 W/m² on average is not much more than the values for

residential use. Setback phases play an important role in school buildings. A tool is available for determining the

expected effective temperature reduction [PHPP 2015] .

In school buildings particular attention should be paid to specific use in summer. Sufficient shading, night-time

ventilation and high internal heat capacity are all imperatives. If it is not possible to meet one of these

requirements, equivalent compensation must be provided – this can be concrete core temperature control or

the use of adequate heat exchangers, for example.

For reheating after setback phases, the central heating generator must be able to provide a sufficiently high

output (in the range of 50 W/m² of heated useable area). The pre-heating phase must be regulated via time

control and internal temperature measurement.

Based on all previous experiences, the Passive House concept has proved to be just as successful for schools,

where it is particularly advantageous due to the ventilation system’s importance.

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7 How to go about it

Why do we have to spend so much time thinking about energy-saving building in renovations, and how can we

motivate people to conserve energy? There are three reasons why we should switch to energy-efficient

construction and renovation as quickly as possible.

1st reason: Europe plans to reduce its carbon emissions by 30-40 percent by 2020 and by 80 percent by 2050.

2nd reason: Along with renewable energy, energy-efficient construction and renovation must compensate for

constantly rising energy costs.

3rd reason: Energy-efficient construction and renovation reduces construction defects and makes buildings

healthier and more comfortable, thereby increasing the long-term value of our buildings.

Climate change affects us all. In order to effectively tackle climate change, we must reduce our energy

consumption significantly in the long term. This means efficient use of available energy and placing maximum

priority on saving energy. Cities and local authorities are important actors when it comes to climate protection –

at the local level, with every individual, every community, in every region.

On average, about 40 % of the total energy consumption in industrialized countries is used for buildings. That is

why significant improvement of the energy efficiency of buildings has considerable impact on the overall

assessment of a town, municipality or urban district in terms of energy. Due to the long service life of buildings,

a consistent approach is especially important in this respect.

For more than 20 years, the Passive House Institute has committed itself to the advancement of the Passive

House Standard, with which an improvement of 40 to 75 % in the energy consumption for heating and cooling

of new builds can be achieved; in the case of refurbishments, reductions of 75 to 95 % are commonplace.

Stefanos Pallantzas, Civil Engineer, Certified Passive House Designer

Athanasia Roditi, Architect, Certified Passive House Designer

Lymperis Lymperopoulos, Architect

Aggeliki Stathopoulou, Civil Engineer

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8 References

[AKKP 42] Proceedings of Research group on cost effective Passive houses 42 “Economic assessment of

energy efficiency measures”. Passive House Institute, Darmstadt 2013 (in German).

[AKKP 39] Proceedings of Research group on cost effective Passive houses 39 “Step by step renovation

with Passive house Components”. Passive House Institute, Darmstadt 2009 (in German).

[EuroPHit] “Improving the energy performance of step-by-step refurbishment”. Intelligent Energy Europe,

2013 - 2016. www.europhit.eu

[Kah et al., 2008] O. Kah; W. Feist; et al: Bewertung energetischer Anforderungen im Lichte steigender

Energiepreise für die EnEV und die KfW-Förderung; Studie im Auftrag des BBR, Darmstadt 2008

[Passipedia] The Passive House knowledge data base. Central parts of research published in German have

been translated and are available online on www.passipedia.org

[PassREg] Passive House Regions - Passive Houses with Renewable Energy. Intelligent Energy Europe, 2012

- 2015. www.passreg.eu

[Schnieders et al., 2012] Schnieders, J.; Feist, W. et al: “Passive Houses for Different Climate Zones”. Passive

House Institute. Darmstadt, May 2012

Athens 15/5/2015

Stefanos Pallantzas, Civil Engineer, Certified Passive House Designer

Engineering

27th elementary school of piraeus final version