27th elementary school of Piraeus enerPHit report

Activity report: Energy performance
and climatic conditions in public spaces
in the MED area – Retrofitting the 27th
Elementary School of Piraeus, Greece
according to the Passive House
Standard
Deliverable No.
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: Municipality of Piraeus ,with the support of ZEB
(S.Pallantzas, Civil Engineer NTUA, Certified Passive House Designer)
Supporting Team: A.Roditi, L.Lymperopoulos, A.Stathopoulou
Submission date: 8/5/2015
Status: Final May 2015

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Contents
1.Building description................................................................................................................................................... 2
1.1. Building identification data ..................................................................................................................................... 2
1.2. Building operational schedule ................................................................................................................................ 3
1.3. Existing Building data............................................................................................................................................. 3
1.3.1. Design............................................................................................................................................................ 3
1.3.2. Building Envelope .......................................................................................................................................... 6
1.3.3. Energy Balance Winter................................................................................................................................. 13
1.3.5. HVAC- Lightning........................................................................................................................................... 15
2. The Passive House Standard ........................................................................................................ 17
2.1. Introduction ......................................................................................................................................................... 17
2.2. Passive House Criteria .......................................................................................................................................... 19
2.3. EnerPHit Standard for existing buildings .............................................................................................................. 20
2.4. Occupant Satisfaction........................................................................................................................................... 24
2.6. Boundary conditions for the PHPP calculation...................................................................................................... 27
2.7. Passive House Standard for Schools ..................................................................................................................... 30
2.7.1. The Air Quality Issue .................................................................................................................................... 30
3. The Enerphit Procedure for the 27th
Elementary School.............................................................. 33
3.1. The building envelope .......................................................................................................................................... 33
3.1.1. The opaque elements................................................................................................................................... 34
3.1.2. Transparent Elements.................................................................................................................................. 36
3.2. The new Ventilation System with Heat Recovery.................................................................................................. 39
3.3. Heating and cooling ............................................................................................................................................. 43
3.4. The overall results of the passive house retrofit ................................................................................................... 44
3.4.2. The summer situation (monthly method) .................................................................................................... 45
4. Conclusion.................................................................................................................................... 48
5. How to go about it....................................................................................................................... 48

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1. Building description
1.1. 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 1-1 depicts the geographical location of the school.
The basic data of the building (according to plans, data provided and on-site measurements) are :
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

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1.2. 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
1.3. Existing Building data
1.3.1. 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 1-2: North Façade Figure 1-3: South Façade

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The layouts of the ground, first, second floors and the elevations are presented in the Figures 1-4, 1-5, 1-6 , 1-7
and 1-8 respectively.
Figure 1-4 : Ground floor
Figure 1-5: 1st
floor

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Figure 1-6: 2nd
floor
Figure 1-7: North and East Elevations

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Figure 1-8 : South and West Elevations.
1.3.2. Building Envelope
1.3.2.1. 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.
Table 1-1, 1-2 and 1-2 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
Teilfläche 1 l[W/(mK)] Teilfläche 2 (optional) l[W/(mK)] Teilfläche 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 Teilfläche 1 Flächenanteil Teilfläche 2 Flächenanteil Teilfläche 3 Summe
100% 27,0 cm
U-Wert-Zuschlag 0,10 W/(m²K) U-Wert: 0,662 W/(m²K)

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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)

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Figure 1-9: 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 1-4 and Table 1-5 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)

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Figure 1-10: Flat Roof Figure 1-11: Sloped Roof
The floor in contact with the ground is covered by marble tiles and is thermally insulated. Table 1-6 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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1.3.2.2. 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 1-12 : Aluminium windows Figure 1-13 : 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)

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Figure 1-14: Glass blocks Figure 1-15 : Glass blocks and Windows in the South facade
In the following tables one can see the characteristics of the transparent elements, as shown in the PHPP.
1.3.2.3. 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.
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 oben
YGlasrand
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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1.3.2.4. 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.
Orientation
Global-
Radiation
Shading
Ver-
schmut-
zung
Non-vertical
Radiation
Glass part g-Value Reductionfactor Radiation Window Area
Window
U-Value
Glass area
Average
radiation
Standardwerte → kWh/(m²a) 0,75 0,95 0,85 m2
W/(m2
K) m2
kWh/(m2
a)
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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1.3.3. 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.

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1.3.4. 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.
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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1.3.5. HVAC- Lightning
1.3.5.1. 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 1-16 : The Gas Boiler Figure 1-17 : Uninsulated pipes
Figure 1-18 : Ceiling fans and splits Figure 1-19 : some fans in the Auditorium

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1.3.5.2. 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 1-10 : 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

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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.
2. The Passive House Standard
2.1. 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 (see image 1). 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.

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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.
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.
2.2. 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).
1
The 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.

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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.
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.
2.3. 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
2) or alternatively through compliance with the criteria of the energy demand method (Table 3). 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 2 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.

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In addition to the criteria in Table 2 or Table 3, the general criteria in Table 4 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).

22
The PHI Low Energy Building Standard is suitable for buildings which do not fully comply with Passive House
criteria for various reasons.

23
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 %
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 6 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.

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2.4. Occupant Satisfaction
o All living areas must have at least one operable window. Exceptions are possible in justifiedcases as long
as there is no significant likelihood of occupant satisfaction being affected.
o 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.
o In case of active heating and/or cooling, it must be possible for users to regulate the interior
temperature for each utilization unit.
o 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.
o 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-

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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.
2.5. 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

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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.

27
On this clearly arranged flow chart you can see 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.
2.6. Boundary conditions for the PHPP calculation
When verifying the criteria using the Passive House Planning Package (PHPP), the following boundary conditions
must be fulfilled:

28
2.6.1. 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.
2.6.2. Calculation method
The monthly method is used for the specific heating demand.
2.6.3. Internal 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.
2.6.4. 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.
2.6.5. 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.
2.6.6. 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

29
2.6.7. 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.
2.6.8. 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.
2.6.9. 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.
2.6.10. 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.

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2.7. 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.
2.7.1. 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)
2.7.2 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

31
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”).
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.

32
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
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

33
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.
3. The Enerphit Procedure for the 27th
Elementary School
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.
In our calculations we have implemented the following steps:
3.1. 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.

34
3.1.1. 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:
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)

35
In the flat roof of the building we have added 100 mm of XPS 034
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)
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)

36
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.
3.1.2. 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,
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)

37
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:
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.

38
Orientation
Global
Radiation
Shadings Dirty
Non vertical
radiation
Glass 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/(m2
K) m2
kWh/(m2
a)
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
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
The installation of the new windows will minimize the installation thermal bridges and improve their
airtightness.

39
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.
3.2. 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.

40
Ground floor: the heat recovery unit is located in the former oil-tank room.
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.

41
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.
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:

42
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.
During summer the ventilation rate will increase by 50%. Night ventilation
trough automatic opened windows will decrease the needs for cooling.
Auswahl des Lüftungsgeräts mit Wärmerückgewinnung
Aufstellort Lüftungsgerät
Wärmebereit- Rückfeuchtzahl spez. Leistungs- Einsatzbereich Frostschutz
zur Lüftungsgeräte-Liste stellungsgrad aufnahme erforderlich
Sortierung: WIE LISTE Gerät hWRG hFRG [Wh/m³] [m³/h]
Auswahl Lüftungsgerät 0,84 0,00 0,45 1300 - 5200 ja
Ausführung Frostschutz 1-Nein
Leitwert Außenluftkanal Y W/(mK) 0,169 Grenztemperatur [°C] 2
Länge des Außenluftkanals m 5 Nutzenergie [kWh/a] 0
Leitwert Fortluftkanal Y W/(mK) 0,169
Länge des Fortluftkanals m 5 Innenraumtemperatur (°C) 20
Temperatur des Aufstellraumes °C 20 mittl. Außentemp. Heizp. (°C) 12,9
(nur eintragen falls Gerät außerhalb der thermischen Hülle) mittl. Erdreichtemp. (°C) 20,7
Effektiver Wärmebereitstellungsgrad hWRG,ef f 83,9%
Effektiver Wärmebereitstellungsgrad Erdreichwärmeübertrager
Wirkungsgrad Erdreichwärmeübertrager h*EWÜ 85%
Wärmebereitstellungsgrad EWÜ hEWÜ 94%
0654vl03-LÜFTA - MAXK I3 6000 DC
1-Innerhalb therm.Hülle
Betriebsarten tägl. Betriebszeiten Maximum Luftvolumenstrom Luftwechsel
h/d m³/h 1/h
Maximum 8,0 1,00 4680 1,16
Standard 2,0 0,77 3600 0,89
Grundlüftung 0,54 2520 0,62
Minimum 14,0 0,40 1872 0,46
mittlerer Luftaustausch (m³/h) mittlerer Luftwechsel (1/h)
Mittelwert 0,63 2952 0,73
PV - PG = 16974 bzw. 15383
Heizwärmelast PH = 16974 W
Flächenspezifische Heizwärmelast PH / AEB = 13,4 W/m²
Eingabe max. Zulufttemperatur 38 °C °C °C
Max. Zulufttemperatur Jzu,Max 38 °C Zulufttemperatur ohne Nachheizung Jzu,Min 19,7 19,8
zum Vergleich: Wärmelast, die von der Zuluft transportierbar ist PZuluft;Max = 17826 W spezifisch: 14,1 W/m²
(ja/nein)
Über die Zuluft beheizbar? ja

43
3.3. 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.

44
3.4. 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:
3.4.1. The winter situation (monthly method)
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%.

45
3.4.2. The summer situation (monthly method)
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.

46
Below is the new energy balance of the building according to PHPP calculations:
EnerPHit-Nachweis
Foto oder Zeichnung Objekt:
Straße:
PLZ/Ort:
Provinz/Land
Objekt-Typ:
Klimadatensatz: ud---02-Athinai-Piraeus
Klimazone: 5: Warm Standorthöhe: 50 m
Bauherrschaft:
Straße:
PLZ/Ort:
Provinz/Land
Architektur: Haustechnik:
Straße: Straße:
PLZ/Ort PLZ/Ort:
Provinz/Land Provinz/Land
Energieberatung: Zertfizierung:
Straße: Straße:
PLZ/Ort: 15234 PLZ/Ort:
Provinz/Land Provinz/Land
Baujahr: 1987 Innentemperatur Winter [°C] 20,0 Innentemp. Sommer [°C]: 25,0
Zahl WE: 1 Interne Wärmequellen (IWQ) Heizfall [W/m2
]: 2,8 IWQ Kühlfall [W/m²]: 2,8
Personenzahl: 260,0 spez. Kapazität [Wh/K pro m² EBF]: 204 Mechanische Kühlung: x
Gebäudekennwerte mit Bezug auf Energiebezugsfläche und Jahr
Energiebezugsfläche m² 1263,8 Kriterien Erfüllt?2
Heizen Heizwärmebedarf kWh/(m²a) 4 ≤ 15 -
Heizlast W/m² 13 ≤ - -
Kühlen Kühl- + Entfeuchtungsbedarf kWh/(m²a) 9 ≤ 15 16
Kühllast W/m² 12 ≤ - 11
Übertemperaturhäufigkeit (> 25 °C) % - ≤ - -
Häufigkeit überhöhter Feuchte (> 12 g/kg) % 0 ≤ 10 ja
Luftdichtheit Drucktest-Luftwechsel n50 1/h 1,0 ≤ 1,0 ja
PE-Bedarf kWh/(m²a) 76 ≤ - -
PER-Bedarf kWh/(m²a) 25 ≤ 45 30
kWh/(m²a) 57 ≥ 60 36
2
leeres Feld: Daten fehlen; '-': keine Anforderung
EnerPHit Plus? ja
Stefanos Pallantzas
ja
ja
alternative
Kriterien
GR-Griechenland
27th Elementary School of Piraeus
Attiki
Municipality of Piraeus
GR-Griechenland
School
Iraklidon 15B
Chalandri
Attiki
GR-GriechenlandAttiki
Ich bestätige, dass die hier angegebenen Werte nach dem Verfahren PHPP auf Basis der Kennwerte
des Gebäudes ermittelt wurden. Die Berechnungen mit dem PHPP liegen diesem Nachweis bei.
ja
Nicht erneuerbare
Primärenergie (PE)
Erneuerbare
Primärenergie
(PER)
Erzeugung erneuerb. Energie
(Bezug auf überbaute Fläche)

47
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, 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.
Anlagenbezeichnung Anlage 1 Anlage 2 Anlage 3 Anlage 4 Anlage 5 PV-Referenzanlage
Standort: Auswahl aus dem Blatt Flächen 3-SLOPED_ROOF 54-2f_ROOF_SLAB
Größe der ausgewählten Fläche 126,4 505,9 m²
Abweichung zur Nordrichtung 180 0 °
Neigung gegen die Horizontale 13 0 °
Alternative Eingabe: Abweichung zur Nordrichtung °
Alternative Eingabe: Neigung gegen die Horizontale °
Angaben aus dem Moduldatenblatt
Technologie 4-Mono-Si 5-Poly-Si 5-Poly-Si 5-Poly-Si 5-Poly-Si 4-Mono-Si
Nennstrom IMPP0 7,71 7,71 7,71 A
Nennspannung UMPP0 30,50 30,50 30,50 V
Nennleistung Pn 235 235 0 0 0 235 Wp
Temperaturkoeffizient des Kurzschlussstroms a 0,040 0,040 0,040 %/K
Temperaturkoeffizient der Leerlaufspannung b -0,340 -0,340 -0,340 %/K
Modulabmessssungen: Höhe 1,658 1,658 1,658 m
Modulabmessungen: Breite 0,994 0,994 0,994 m
1,6 Modulfläche [m²]
Weitere Angaben
Modulanzahl nM 50 50 0,0
Höhe des Modulfelds 1,0 1,0 m
Höhe des Horizonts hHori 0,0 0,0 m
Horizontentfernung aHori 15,0 15,0 m
zusätzlicher Abminderungsfaktor Verschattung rso
Wirkungsgrad des Wechselrichters hWR 95% 195% 95%
Ergebnisse
Fläche des Modulfeldes 82,4 82,4 0,0 0,0 0,0 0,0 m²
Freie Fläche auf dem ausgewählten Bauteil 44,0 423,5 m²
Belegung des Bauteils 65% 16%
Jahresverluste durch Verschattung 0 0 kWh
Summe
Jahres-Stromertrag nach Wechselrichter Absolut 15704 29909 45613
Bezogen auf die überbaute Fläche 19,5 37,2 57
Spezifischer PE-Faktor (nicht erneuerbare Primärenergie) 0,30 0,11 kWhprim_ne/kWhEnd
Spezifischer CO2-Äquivalent-Emissionskennwert der Anlage 44,5 20,9 g/kWh
CO2-Äquivalent-Emissions nach 1-CO2 -Faktoren GEMIS 4.6 (Deutschland) 2104,4 3110,5 5214,9

48
4. 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.
5. 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.

49
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.
Athens 8/5/2015
Stefanos Pallantzas, Civil Engineer, Certified Passive House Designer
Athanasia Roditi, Architect, Certified Passive House Designer
Lymperis Lymperopoulos, Architect
Aggeliki Stathopoulou, Civil Engineer

27th elementary school of Piraeus enerPHit report

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