Cost Efficient Passive Houses as European Standard

Surname: Vourvoutsiotis Name: Apostolos

Address: Gartenstrasse 14

City: Schwaig Code: 90571 Country: Germany

Tel: +49 (0)911 500 95 22 Fax: +49 (0)6151 8269

E-mail: apostolosv@primus-online.de

Abstract

Nowadays the passive house model is a more developed and in Central Europe accepted, way of cost and energy efficient building.

Passive Houses are buildings in which a comfortable climate can be achieved without an active heating and air-conditioning system and with approximately zero CO2 emissions.

A passive house thus consumes in total, less energy then is required in average European buildings for household electricity and domestic hot water alone. The total final energy consumption of a passive house is thus lower by at least the factor 4 than the average consumption encountered in new buildings and pursuant to the applicable national regulations.

1

1. INTRODUCTION

Buildings with good environmental performance and especially with low energy consumption are of increasing demand and constitute the future of the building market. Nowadays the passive house model is a more developed and in Central Europe accepted, way of cost and energy efficient building. At the past these houses were called “zero energy houses” and there was an early research project by Prof. Koorsgaard of the Technical University of Denmark in the early seventies. With a grant of the Hessian government the research project “passive house in Central Europe” started in 1988 and the construction in October 1990 (Feist, 1995).

Two Hundred fifty-eight (258) dwellings in cost efficient Passive Houses shall be built in 1998/1999 in 5 North and Central European Countries through CHEPHIUS project (Cost Effective Passive Houses as European Standard) under the THERMIE programme as a demonstration action.

2. WHAT IS A PASSIVE HOUSEPassive Houses are buildings in which a comfortable interior climate can be achieved without an active heating and air-conditioning system.   To permit this, the specific annual demand for space heating must be kept lower than 15 kWh/(m2a), and the total final energy demand for space heating, domestic hot water, ventilation and household electricity must not exceed 42 kWh/(m2a).  This forms the basis to cover the remaining energy requirement totally by renewables. 

Figure 1. Comparison of energy performance indexes for dwellings Source: Dr. W. Feist, The Passive Houses at Darmstadt, page 6, April 1995

A passive house thus consumes in total less energy than is required in average new European buildings for household electricity and domestic hot water alone. The total final

2

energy consumption of a passive house is thus lower by at least the factor 4 (space heating –80%, domestic hot water –60%, household electricity –60%) than the average consumption encountered in new buildings and pursuant to the applicable national regulations (3.PHI,1998).

 3. INNOVATIVE TECHNOLOGIES

The decisive point is: If efficiency is improved to such a degree that the remaining heat requirement of the house is not zero, but so low that a conventional separate heating system can be dispensed with without lost of comfort to the occupants, then the absence of the necessity to invest in heat distribution and radiative systems provides a downwards cost leap that finances the superinsulation measures inclusive of superglazing and high efficiency heat recovery.

Figure 2. Cross-section of the Passive House at Darmstadt, Kranichstein. Source: Dr. W. Feist, The Passive Houses at Darmstadt, page 8, April 1995

Passive energy saving technologies have a decisive benefit: No further elements are required in addition to a conventional building. It is only necessary to construct the components that are used in any case (floors, outer walls, windows, roofs and ventilation) to better quality standards than is usual. Over the medium term, such a quality improvement need not cause higher investment costs than in a standard house.

3

Particularly through the prefabrication of high-quality exterior building elements, such components can be produced very cost-effectively.

Detailed considerations show that the maximum heat load can readily be transported with the supply air in a passive house. This heat load corresponds to a permissible annual heat requirement of 15 kWh//(m2a) - a value that is achievable with the innovative technologies described in the following. (The Darmstadt-Kranichstein Passive House prototype has achieved 12 kWh/(m2a). The remaining heat requirement can be covered by supplementary heating of the supply air that is required for hygienic reasons, by means of recovering latent heat from the extracted air.

3.1. Insulation

Standard low energy houses are insulated on the outside of the masonry wall with 12 to 20 cm polystyrene panels. In passive houses this insulation has to be improved: 25 to 40 cm should be used in order to achieve U value equal to 0,1W/(m2K). Another solution is a timber construction using l-studs or box-studs and about 40cm of blown insulation material. This construction has been used for the roof of the passive house (Feist, 1995).

Thermal bridges have to be carefully reduced in passive houses. Detailed planning as well as high construction quality is required in order to minimize the thermal bridges.

3.2. Window quality and quantity

Double pane low-e-glazing with U=1,5W/(m2K) and Argon in the space has become the commonly used glass quality in new houses. The heat losses are half of those of standard double pane units. In Passive House is used a new superglazing with 3-panes and U=0,7W/(m2K), having 2-low-e-coatings on surfaces to the spaces, which are filled with Krypton. These superglazings do have only half of the energy loses compared to 2-pane-low-e, so this is the glass quality, it can be used for efficient passive solar houses. The solar heat gains through this glazing are higher than the heat losses even in December and January (Feist, 1995).

 

Figure 3. Comparison of different glazing types per glazed area facing South, Source: Dr. W. Feist, The passive House at Darmstadt, page 13, Darmstadt, April 1995

However the problem with the windows is the thermal bridge resulting from the spacers and the heat losses of the windows frames. The solution for the Passive Houses is the use of insulated window frames with U value lower than 0,8 W/(m2K).

3.3. Airtightness

4

Passive house has to be very airtight. 50 Pa-pressurization-tests for good Swedish practice are within 1 to 2 ac/h. The objective for the passive house was 0,6 ac/h but has been measured values between 0,2 and 0,4 ac/h in Kranichstein passive house (Feist, 1995).

3.4. Ventilation and heat recovery

For the ventilation of the passive a high efficient heat exchanger (80-90%) is used in combination with buried tubes in order to achieve an interior comfortable climate. The buried tubes preheat the fresh air during the winter and cool the air during summer. Hygienic ventilation is achieved with the extraction of the air from the damp rooms (kitchen, WC). The annual energy consumption of the heat exchanger is lying among 200 and 400 kWh/dwelling. The recovered heat is lying among 3000 and 4000kwh/a. Thus the energy consumption of the heat exchanger is at least the factor 10 lower than the recovered heat (4.PHI, 1998).

Component Characterization Specification  Building  envelope Super insulated U around 0.1 W/(m2K)

  Building element junctions Reduced thermal bridging Ulin around 0.0 W/(m2K)

  Airtightness Airtight building envelope n50 around 0.5 ac/h

Subsoil  heat exchanger Fresh air preheating fresh air  over 8oC

Hygienic ventilation directed air flow through whole building; exhaust air extracted from damp rooms

total around 140 m3/h or1m3/h/m2

 Heat recovery Counter-flow air-to-airheat exchanger

>80%

Latent heat recovery from exhaust air

compact heat pump unit for water heating

max. heat load 1000 watts annual COP> 3

monovalent system Passive utilization of solar energy optimized glazed areas approx. 40% coverage of

space heat requirement

 Superglazing 3-pane low-emissivity glazing

U-value < 0.7 W/(m2K)g-value 50%

 Superframes superinsulated window frame

U-value < 0.8 W/(m2K)

Solar flat plate collectors integrated in facade 50% coverage of water heating

Household appliances high-efficiency low-energy household appliances

savings of over 50%

Supply of remaining energy demand from renewable sources

only Hannover-Kronsberg project: share in wind power

facility

100% demand coverage over annual average in Hannover

Table 1. Overview: Innovative technologies in the Passive House, Source: CEPHEUS, Cost Efficient Passive House as European Standard, Passive House Institute, www.passivehouse.com, Darmstadt 1998

4. COST EFFICIENT PASSIVE HOUSE

5

When the energy efficiency of the building is improved by thicker insulation, superinsulation windows and heat exchanger, the annual requirement for space heating sinks, but the construction costs for the building are increased (figure 4). At first look seems not to be economically feasible, when the annual heating demand is lying under 30 kWh/(m2a). Because this was the widespread view of the property developers in Europe, only some attempted to construct buildings with even better insulation measures. The paradigm however sways because the knowledge of the Passive House concept presents that: when the annual heating demand is under the threshold value of 15 kWh/(m2a, then a separate heating system is no longer necessary.

The cost saving of the heating system absence can finance a big portion of the additional cost for the high efficient ventilation, the low-e-windows and the improved insulation.

Figure 4. Capitalization of the total cost as function of the annual requirement for heating, Source: Kostengünstige Passivehäuser in Mitteleuropa, Passive House Institute,www.passivehouse.com, Darmstadt 1988

The overheads of a Passive house furthermore are extremely low (100 to 200 DM annual heating cost). A passive house is cost efficient, if the capitalized total costs (investments in the building incl. planning and building services plus running costs over 30 years) are not higher than in an average new building. The Passive House standard will become the construction with the lowest total costs within some years; This is a result of the increasing Market demand for Passive House suitable components. (It is already achievable the construction cost for a Passive House under 2.000 DM/m2 in Germany).

5. PROJECTS

The first Passive House:

64289 Darmstadt Kranichstein (Hessen) 4 Dwellings, 156 m2 per dwelling, 1991

CEPHEUS project under the THERMIE programme.Cost-efficient passive houses have been built in 1997/1998 in 5 European countries. The houses shall be inhabited from 1998/99 onwards. In each national project, one dwelling shall be made available for visitors and consulting functions. The associated

6

measurement programme shall be scientifically evaluated. The countries in which passive houses are to be built are: Sweden (40 dwelling units), Germany (70 dwelling units), Austria (108 dwelling units), Switzerland (10 dwelling units) and France (40 dwelling units).Passive house projects:Sachsen: 04205 Miltitz, 1 single house, 160 m² , 1998 04249 Leipzig - Knauthain, 1 single house, 141 m² , 1998 Brandenburg: 15366 Neuenhagen, 2 single houses,1997 Hamburg: 21029 Hamburg, 1 single house,1997 Niedersachsen: 21386 Betzendorf, 1single house,1998 21423 Winsen, 1single house,1998 21435 Stelle, 1single house,1998 29549 Bad Bevensen, 1single house,1997 29556 Suderburg, 1single house,1998 Hessen: 34131 Kassel / Marbachshöhe, 40 social dwellings. Gemeinnützige

Wohnungsbaugesellschaft der Stadt Kassel mbH (GWG),1998 35091 Cölbe, the first office building as passive house 2.180 m2 in 3 stores, April 1997

/ March 1998 34311 Naumburg, 2 single houses, 125 m2 per house 35116 Hatzfeld / Eifa, 1 single house,1998 61169 Friedberg-Ossenheim, 24 dwellings, 1998 64579 Gernsheim, 1 double dwelling,1999 64686 Reichenbach / Odenwald, 1 single house, 200 m, 1998 65366 Geisenheim-Marienthal, 6 dwellings, 1998 68518 Viernheim, 14 dwellings in 2 blocks, 1998/1999 65197 Wiesbaden, 46 dwellings in 6 blocks, 1997Nordrhein Westfalen: 42327 Wuppertal, 22 dwellings in 3 blocks,1999 51789 Lindlar-Hohkeppel, 5 single houses, 1997 / 1998 Baden-Württemberg: 71397 Leutenbach, 3 family house,1997 71522 Backnang-Waldrems, 1 single house,1998 71691 Freiberg a.N. , 1 double dwelling, 1997 73563 Mögglingen, Ostlabkreis, 1 single house, 1998 73734 Esslingen, 1 single house,1997 74259 Widdern-Unterkessach, 1 single house, 1997 75015 Bretten, 1 single house,1997 / 1998. 75015 Bretten, 1 single house, 1998. 76646 Bruchsal / Büchenau, 1 house,1998 76689 Karlsdorf , 1 single house, 1998 77815 Bühl-Neusatz, 3 dwellings, 1997 / 1998 77836 Rheinmünster-Schwarzach, 7 dwellings in 2 blocks, 1997 / 1998 79395 Neuenburg am Rhein, 7 dwellings, 1998 88682 Salem – Mittelstenweiler, 1 single house, 1998

7

Bayern: 87616 Stadt Marktoberdorf, 1 double dwelling, 1998 88167 Maierhöfen, 1 single house, 1998 96047 Bamberg, 1 single house, 1998 96135 Mühlendorf, 1 single house, 1997 / 1998 96253 Untersiemau, 1 single house, 1997 / 1998 Austria: Dornbirn (Vorarlberg / Österreich) Projekt "Ölzbündt", 12 dwellings, Juny1997.

REFERENCES

1. Feist, Dr. Wolfang, 1995, The Passive House at Darmstadt/Germany, Institute for Housing and Environment, Darmastadt

2. Institut Wohnen und Umwelt (IWU), 1994, Das Energiesparhaus der Zukunft, Passivhaus Darmastadt Kranichstein, Institut Wohnen und Umwelt, Hessisches Ministerium für Umwelt, Energie und Bundesangelegenheiten, Darmstadt

3. Passive House Institute (PHI), 1998, CEPHEUS Cost Efficient Passive House as European Standard, Passive House Institute, www.passivehouse.com, Darmstadt

4. Passive House Institute (PHI), 1998, Kostengünstige Passivehäuser in Mitteleuropa, Passive House Institute, www.passivehouse.com, Darmstadt

5. Passive House Institute (PHI), 1998, Passivhaus Projekten, Passive House Institute, www.passivehouse.com, Darmstadt

8