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Simplify your building City of Frankfurt adopt Passivhaus Riedberg Primary School Kalbacher Hรถhe, Frankfurt am Main



Decisions to Passivhaus requirements, results and implications economy Simple und small is beautifull: HVAC and building control in a Passivhaus chances of renovation, reconstruction HVAC lighting and summer heat protection Examples and more result

Prof. Axel.Bretzke,

Passivhaus-school, slide 2

27.02.2003 city-parliament of Frankfurt: The small additional costs attest that kindergartens and schools should be built to passivhaus quality

Prof. Axel.Bretzke,

Passivhaus-school, slide 3

2005: Frankfurt residential building company (ABG) „overwhelming success in selling PH residential buildings“ CDU: Passivhaus should be standard

Prof. Axel.Bretzke,

Passivhaus-school, slide 4

2006 city government decide: New city buildings should be built according to the guidelines for economic construction That means not only PH standard, but also economic, sustainable buildings Awards for the city of Frankfurt for building according to the Frankfurt „guidelines for economic buildings“: EU-Greenlight Award 2006, Greenbuilding award, a.s.o. sh.htm Prof. Axel.Bretzke,

Passivhaus-school, slide 5

Content: guidelines for economic buildings energiemana gement/engl ish/english. htm

Prof. Axel.Bretzke,

Passivhaus-school, slide 6

Sept. 2007, City parliament of Frankfurt, PH-decision The municipal administration has to ensure that all new buildings for the municipal administration, urban institutions and corporations and all buildings in the Framework of PPP for the city of Frankfurt will be built and designed accordingly the PHstandard. If a design fails to meet this standard, this has to be justified For renovations PH-standard is the aim. To fail this aim has to be justified also. Where the municipality sells land, there has to be a contractual agreement that any new construction satisfies the PH-standard a.s.o

Prof. Axel.Bretzke,

Passivhaus-school, slide 7

PH decision, Frankfurt and beyond 

2006/07 City of Leipzig, city of Wiesbaden, city of Aschaffenburg, City of Antwerpen, County Lippe, County Erding, Wels Austria: PH is standard

Vorarlberg, Austria: government funding for residential buildings only for PH standard

Belgium/Flandern 2007/08: Decision for new school buildings to PHstandard. Minister and parliament visit Riedberg primary school before

GB government: PH should be standard from 2013?, zero carbon standard from 2016 (code level 6 for sustainable homes)

France: Loi Grenelle 1+2: new buildings primary energy demand < 50 kWh/m2 a from 2010 (NRB) and 2012 (residential buildings)

Prof. Axel.Bretzke,

Passivhaus-school, slide 8

PH decision, Frankfurt and beyond EU-EPBD (2010): Target Energy for all buildings: â&#x20AC;&#x201C; 20% till 2020  all new buildings are nearly zero- energy buildings by 31 December 2018 if they are occupied and owned by public authorities, and after 31 December 2020 all others!  national plans for increasing the number of nearly zero- energy buildings Member States shall report to the Commission by 30 June 2012 - intermediate targets for improving the energy performance of new buildings, by 2015, with a view to preparing the implementation till 2017  regular inspection of energy performance of heating and airconditioning systems in buildings  methodology for calculating the integrated energy performance of buildings and building units, common general framework  minimum requirements to the energy performance of existing buildings, building units and building elements for major renovation  energy performance certificates for public buildings, displayed in a prominent place clearly visible to the public, over 500 m2, 2015 > 250 m2 Prof. Axel.Bretzke,

Passivhaus-school, slide 9

What is a Passivhaus? criteria: 

Demand for heat and cooling

recommended criteria:  Primary energy  Effiency for ventilation:  airtightness:

<= 15 kWh/(m2 a) <= 120 kWh/(m2 a) <= 0,45 Wh/m3 <= n50 < 0,6 /h

other:  add. heat for warm water and boiler loss ~  power consumption for ventilation/person: <  Power cons. for ventilation 500 pupils,+staff ~  Amount for heating and ww, 500 pupils+staff ~  Heat loss for a classr. with open windows a y.~

10-20 kWh/(m2 a) 6-9 kWh/(Person a) 3600 kWh/a ~ 720€/a * 150 MWh/a ~ 7000 €/a 1 kWx24h/dx100d/a ~ 200€/a

Economic amount for controlling and technique? * price D: price Estonia:

electricity: 0,15€/kWh, heat: ~ 0,06 €/kWh, electricity: 0,06€/kWh, heat: ~ 0,04 €/kWh Prof. Axel.Bretzke,

Passivhaus-school, slide 10

What does a Passivhaus school need? in comparison to German low energy standard (RAL)  More insulation with 20-35 cm (wall-roof, λ 0,032 W/mK, Estonia ~1/4 more, degree days D ~ 3000 kd, Estonia ~ 4000 kd)  Better windows (Uw 0,8 instead of 1,1 W/m2K)  Mechanical basic ventilation (20 m3/h per person in passivhaus) with heat recovery > 75% according to EN 13053 and efficiency (SFP 1-2 acc. EN 13779 ~ 0,45 Wh/m3) for classrooms. Already required in gym and kitchen  Airtight construction (as standard, but more careful execution)  PH is simpler and gets better economy with better adapted volume (gross volume/central used area (classrooms, office etc.) < 6) and less than 50% windows to the north than south  Fewer and smaller technical systems, substantially (x 5) smaller heating (10W/m2), simpler controls (how much do you need for 5000 €/a heating and 500-1000€/a for ventilation for a whole school?) Prof. Axel.Bretzke,

Passivhaus-school, slide 11

Relation in a Passivhaus invest for regulation and control to saving potentials classroom

 A good reference point for additional expense for a control system justified by energy savings and comfort is an acceptable relationship of investment and maintenance to the lower energy costs and the generally high comfort of a PH

Prof. Axel.Bretzke,

Passivhaus-school, slide 12

Why a school to Passivhaus quality? Heating In a PH school the heat from 25 pupils and a teacher is enough (1.5 kW), to keep the classroom comfortable warm during the whole year , especially with heat recovery. Therefore the main purpose of the heating system is to stop the school getting too cold over weekends and holidays.  Therefore the heating works best with small radiators, not using the ventilation. In schools the capital costs are about the same whichever way you do it. For comfort and easy control we decided to use one small radiator on an internal wall of a classroom.  No space loss by heating element under the window, which saves construction costs  Control is simplified. The only reason you need individual room control is for comfort: the heating costs are already negligible  A PH school is good-natured. Even if the heating system fails for a few days, the pupils can keep the classroom temperature above 20oC 

Prof. Axel.Bretzke,

Passivhaus-school, slide 13

Why a school to Passivhaus quality? Costs and planning 

Economy has been proven in several cases (by total cost computation), the extra capital cost is about 5-10%, depending on the size and architectural design.

To calculate a passivhaus, take the nett present value of the saved running costs (energy, maintenance etc. over 20-40 years), and look, what you can get for it at the actual market (insulation, PH-windows, mechanical ventilation). Mostly the saved amount is more than the extra capital cost for the PH. For free and additional you get a better climate (internal and global) and your building has a higher market value

The energy costs are reduced to 1/5-1/20. In relation to a new and existing buildings, they are negligible  You need architects and other design team members with an obsession for good quality, simple and creative solutions, a knowledge of building physics and some prior experience of energy efficient buildings. 

Prof. Axel.Bretzke,

Passivhaus-school, slide 14

What additional investment? Offer in german building stores 2008/2010: â&#x20AC;&#x153;Get triple glazing for the price of double etc.â&#x20AC;?

Germany 2010: triple glazing 40% of the market Prof. Axel.Bretzke,

Passivhaus-school, slide 15

Differences in costs between standard and PH designs


Invest/m2 0






Present value of saved running costs (energy)etc.







Present value of saved running costs PH



Value of investment, depending on architectual design -2000


Normal financial uncertainty in final design estimates

Prof. Axel.Bretzke,

Passivhaus-school, slide 16

Range of capital costs for different architectural designs for the same building type from: ebรถk, Wirtschaftlichkeit energiesparenden Bauens, Heidelberg 2004)

Additional investment for PH

Prof. Axel.Bretzke,

Passivhaus-school, slide 17

compactness and building costs, comparing LowEnergy (NEH) and PH

Univ. Prof. Arch. DI Dr. Martin Treberspurg, DI Roman Smutny, DI Roman Gr체nner ANALYSE DER BENUTZERZUFRIEDENHEIT UND ENERGIEPERFORMANCE ausgew채hlter Wiener Passivhaus-Wohnhausanlagen, Reader 14. Internat. PH-Tagung Dresden 2010

Prof. Axel.Bretzke,

Passivhaus-school, slide 18

Additional investment result 2005 for PH-quality, compilled for a grant for the Riedberg primary school Component


design 18%









23.600 2160 m2, insulation and structure

windows, glazing



25.900 1780 m2, PH-glazing, 75-100€/m2

suspended ceiling






28.000 3600 m2 , insulation

ventilation, heating



29.600 3 extra ventilation plants, but less heating and central building control



8.300 insulation

9.000 2560 m2

118.600 124.400 approx. 900.000 € 5.3 % of 16.7 million €

Part Prof. Axel.Bretzke,

Passivhaus-school, slide 19

Average total life cycle costs for PH-primary school at Preungesheim (for 40 years) â&#x201A;Ź/a 2.000.000 1.800.000 1.600.000 1.400.000 1.200.000 1.000.000 800.000 600.000 400.000 200.000 0 german Low EnergyPassivhouse Standard standard (EnEV) Frankfurt (EnEV-30% )

Invest service and maintenance electricity ecology



Cleaning heating water administration

Prof. Axel.Bretzke,

Passivhaus-school, slide 20

Heating costs for PH-primary school at Preungesheim heating 100,000 80,000 60,000 Ū/a 40,000 20,000 0 Standard (EnEV)

Low Energy Passivhouse standard (EnEV 30% )

reduced energy-costs over lifetime ~ possible amount to pay more for a PH: (valueStandard (kWh/m2a) - value PH(15kWh/m2a) ) x GFA (m2) x energyprice(€/kWh), Ø40a!) x lifetime Prof. Axel.Bretzke,

Passivhaus-school, slide 21

Riedberg primary school, results 

Consumption for heating school and kindergarten, conditioned floor area 5540 m2 2008: 14,9 kWh/m2

Prof. Axel.Bretzke,

Passivhaus-school, slide 22

reduction loss only 50%, reduction heat demand to Âź !

Prof. Axel.Bretzke,

Passivhaus-school, slide 23

1. Gesamtkosten Konzeption und Gestaltung: Hochbauamt der Stadt Frankfurt, Abteilung Energiemanagement

Total cost calculation for the city of Frankfurt energiemanage ment/pro.htm


Allgemeine Daten







A11 Preissteigerung Ene./son.

A2 Unterab. Grundschule Preungesheim A4 Str.-Nr. Grundschule, KT, Jugenhaus, Turnhalle A6 Haus-Nr. Boskooppstraße A8 Währung € 40 a A10 Annuitätsfaktor 3,5% 0,05 5% 3% A12 Mittelwertfaktor Ene./son. 2,55







EnEV - 30%



EnEV EnEV - 30% Passivhaus


Variante 3


Variante 4








Bezugsfläche (NGF)




spez. Heizwärmebedarf


Heizzahl Kessel+Verteilung


spez. Strombezug


spez. CO2-Emissionen


spez. Trinkwasserbezug




Investitionskosten (DIN 276)








spez. Kapitalkosten


6.723 550 172 90% 14 49 3,87 EnEV

EnEV - 30%


6.723 550 104 90% 13 34 3,87 EnEV - 30%

6.723 550 17 87% 13 11 3,87 Passivhaus

mittl. Betriebskosten










81.477 203.053 88.106 27.030 8.246

81.477 207.036 55.742 24.460 8.246

81.477 223.423 5.710 24.800 8.246




heutige Betriebskosten


mittl. Betriebskosten


spez. Betriebskosten

407.911 791.007 118

376.960 708.671 105

343.654 609.764 91




Trinkwasser (1 €/m³)




spez. Umweltfolgekost.



EnEV - 30%



spez. Gesamtkosten

kWh/m²a kg/m²a m³/P a Variante 3

Variante 4 €

0 0 0 Variante 3

0€ 0 €/a 0 €/m²a Variante 4 €/a €/a


0 €/a €/a €/a €/a

16.636 2.130 18.766 3 EnEV

EnEV - 30%


11.294 2.130 13.425 2 EnEV - 30%



0 €/a


0 €/m²a

€/a Variante 3

7.184 2.130 9.314 1

1.730.916 1.663.788 1.642.109 257 247 244 G2 Amortisationszeit (Basis: Variante 1) 5,6 14,8 G1




CO2-Emissionen (50 €/to)

6.723 m² 550 P kWh/m²a

19.671.071 20.109.911 21.846.895 921.143 941.692 1.023.031 137 140 152



Variante 4

6.723 550

19.671.071 20.109.911 21.846.895



Variante 3


Variante 4

0 0 0 0 Variante 3

0 0 0 0

€/a €/a €/a €/m²a

Variante 4

0 0

0 €/a 0 €/m²a a

(alle Kosten sind Bruttokosten incl. MWSt.)

Prof. Axel.Bretzke,

Passivhaus-school, slide 24

Riedberg school, data User

•400 Primary school children in 16 classes •100 - 125 children in kindergarten over the year, •50 staff, including kindergarten, maintenance, kitchen

Effective area NGF

•School and kindergarten 6100 m2 nett, 5540 m2 treated floor area, area:volume ratio 0.35 •Sports hall 1600 m2

Gross floor area, Gross volume

•8785 m2 •40347 m3

Characteristic energy values in relation to passivhaus standards

•for heating 14.9 – 22.3 kWh/m2a PH: 15 •including hot tap water ~ 25 kWh/m2 a •heat load: 10,5 – 15 W/m2 PH: 10 •air leakage, per hour at 50 Pa n50:0.46/hPH: 0,6 •specific fan power: ca. 0.43 Wh/m3 PH: 0,45 •primary energy: 59 kWh/m2a PH: 120 •electricity consumption 11 kWh/m2 a •classroom lighting: 5.6 W/m2 1.9W/m2/100 lux

Prof. Axel.Bretzke,

Passivhaus-school, slide 25

Riedberg school, primary energy, actual, 0-energy electricity all: part. el. Kitchen: Photovoltaik:

130 MWh/a 58 MWh/a 27 MWh/a

Heat (woodpellet) incl. WW:

200 MWh/a

Primary energy, school with kitchen: (130-27)*2,6 + 200*0,2 =

157 MWh/a

(~ 20 without kitchen!)

~ 40 kWh/m2 a

For â&#x20AC;&#x17E;0â&#x20AC;&#x153; we need add. 129 kW PV (~2000-2600m2) more. The school with gym has about 4000 m2 roof area, actual 600 m2 with PV! Zero emission or zero energy will be no problem, for instance with PV. Prof. Axel.Bretzke,

Passivhaus-school, slide 26

Air quality in classrooms, peak CO2 levels CO2-Messungen in Klassenr채umen von 1858-2000 8000

Window ventilation

CO2-Konzentration [ppm]


Mech vent.

6000 5000 4000 3000 2000 Grenzwert 1500 ppm 1000 0 Pettenkofer 1858

Heck 1921

CH-D체bendorf 1989

Stammheim 1989

Source: IWU, Stahl-Sonnenenergie

Prof. Axel.Bretzke,

CHGumpenwiesen 1989

PH-SchuleWaldshut 2000

Passivhaus-school, slide 27

Performance of pupils is affected by air supply rates

Source: Professor Dr. Ing. Bjarne W. Olesen International Centre for Indoor Environment and Energy

Prof. Axel.Bretzke,

Passivhaus-school, slide 28

Why a school of Passivhaus quality? Mechanical ventilation system 

Durable, sufficient air quality and good humidity according to standard (> 35%, <1500 ppm) for better learning effort ensures the mechanical ventilation (exact 18-20 m3/h per person acc. Ida4 from EN 13779) without air conditioning. Energy efficiency according to EN 13779 SFP1-2 and heat recovery > 75 % ensures a low energy consumption overall. Small central units with plate heat exchangers with no recirculated air guarantees pollution, allergenic, dust and germ free fresh air. Outside the short heating season the passivhaus school should be ventilated with opening windows (0,1-0.3 m2/P). Even in the heating season you can open the windows for extra ventilation if necessary. Concentration and compliance rises significant

Prof. Axel.Bretzke,

Passivhaus-school, slide 29

Example of a simple system In

Ventilation for a gym out

Ceiling radiant panels

Ventilation central unit

natural ventilation 0,05-0,1/h ~ 300-500 m3/h


One pitch sports hall

Showers locker room Air transfer Fresh air for 25 persons 500-1000 m3/h

Prof. Axel.Bretzke,

Passivhaus-school, slide 30

Dimension for ducts in a school for 6 classrooms

Prof. Axel.Bretzke,

Passivhaus-school, slide 31

Space for putting ducts

suspended ceiling 300-400 mm

Height to suspended ceiling min. 2.6 m

Classroom height 3.0 m to exposed concrete ceiling

Cupboard wall

Prof. Axel.Bretzke,

Passivhaus-school, slide 32

Space for a fresh air duct only you find in every Fire protected ducts solid line

building Self-closing fire dampers


Prof. Axel.Bretzke,

Passivhaus-school, slide 33

If windows are opened in winter

Standard Much heat loss

Passivhaus less heat loss Air Heat exchanger



Prof. Axel.Bretzke,

Passivhaus-school, slide 34

Why a school of Passivhaus quality? windows 

Even in winter you can provide additional ventilation with the windows if necessary.

Much less useful heat is lost through an open window in a passivhaus than in a normal building (much smaller radiator at the corridor wall only).

The user will close an unnecessarily open window automatically, because there is no radiator heating the cold, incoming air  The passivhaus window quality guarantees comfort in winter, even at a seat beside the window, with no radiator underneath. 

Outside the short heating season the passivhaus school is ventilated with the open windows, use 0,1-0,3 m2/person.

In summer the passivhaus school guarantees a better indoor climate (less hot) than a standard school. But in any case you have to provide effective summer solar gain protection, and reduce the glazing area to the amount you need for lighting. Prof. Axel.Bretzke,

Passivhaus-school, slide 35

Summer heat protection Window with shading fc 0,2 10 m2

Solid Wall 10 m2 P = 2 kW

Problem: 25 â&#x20AC;&#x201C; 30 pupils with  Even with shading 5 max. 80 W times more solar and internal gains comes in than you need in winter for transmission losses  Much less is going out through fabric transmission, in both, standard and PH buildings Therefore:  Store the heat in the floor, ceiling and wall  let it out by ventilating at P = 2 kW night

Prof. Axel.Bretzke,

Passivhaus-school, slide 36

Summer heat protection in every school is a challenge, for the Passivhaus standard it is a little easier The heat gains into classroom during the day (internal and solar gains) are about 15-20 kWh (more than in an office building!), while the loss at night through the facade is only 2-4 kWh.  Thermal mass (ceiling, floor inner wall) has to be built in to be able to store the thermal load and be ventilated out with cold air in the night. 

Optimising the window area (just enough for daylight whilst keeping solar gains to minimum), have high window heads for better daylight, reduce glazed area below desk-top level to minimise solar gain.

An automatic sunshading system is necessary, with manual over-ride control, reverting to automatic after a few hours.

Reduce internal gains (with efficient lighting, PCs and so on)

The heat stored in the fabric has to be removed by night ventilation. A ventilation opening with both automatic and manual is the simplest and most robust system: if you use mechanical ventilation, both capital and operating costs will be higher. Prof. Axel.Bretzke,

passivehouse-school, Passivhaus-school, Folie slide 37

Night ventilation and cooling at Riedberg PH school

 Manual regulation possible for most control systems (lighting, sunshading, night-ventilation for day use, thermostatic valve), overdrived automaticly after programmable time (central lighting switch of, sunshading, night-ventilation) Prof. Axel.Bretzke,

Passivhaus-school, slide 38

Riedberg primary school, Classroom with long throw ventilation slot, acoustic ceiling, acoustic pinup wall, efficient lighting 

Prof. Axel.Bretzke,

Passivhaus-school, slide 39


Prof. Axel.Bretzke,

Passivhaus-school, slide 40

Plan of site

Prof. Axel.Bretzke,

Passivhaus-school, slide 41

Passivhaus certificate

Prof. Axel.Bretzke,

Passivhaus-school, slide 42

Example 2

Waldshut Energy-saving School

Prof. Axel.Bretzke,

Passivhaus-school, slide 43

Example 3 Montessori primary and secondary school in Aufkirchen (Munich) â&#x20AC;˘

Prof. Axel.Bretzke,

Passivhaus-school, slide 44

Example 4 Primary school with Kindergarten, youth centre and gym in Frankfurt-Preungesheim

Prof. Axel.Bretzke,

Passivhaus-school, slide 45

more Examples       

PH-Factories PH office building PH nursing home PH police station PH church PH Hotel PH gym Sorry but this link is not very up to date: Prof. Axel.Bretzke,

Passivhaus-school, slide 46

Problem Where do Passivhaus designers grow?

You need architects and other designers with a dedication to good quality and simple and creative solutions, a knowledge of building physics and some experience of energy efficient buildings. To ensure passivhaus quality, some members of the architectural and engineering team should have prior passivhaus experience.

If not, the team will need an adviser (e.g. from the Passivhaus Institute)

For integrated design, all design team members need to be on the team from the beginning

You need fine tuning processes, in order to avoid or correct errors

You need to review your specifications against the targets as design and construction progresses.

Prof. Axel.Bretzke,

Passivhaus-school, slide 47

The Passivhaus building method is architecture and construction supervision with special requirements   

for experience for addressing the task in hand for the quality of workmanship and simple and creative details To get


favourable construction costs Good comfort Sustainable buildings with low energy costs Prof. Axel.Bretzke,

Passivhaus-school, slide 48

Prof. Axel.Bretzke,

Passivhaus-school, slide 49

Simplify your building. City of Frankfurt adopt Passivhaus.  

Axel Bretzke presentation in conference "Live Wise: Energy-efficient buidings, development models" March 17th 2011, Tallinn Estonia.

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