ENERGY SUSTAINABILITY BY THE PASSIVE HOUSE STANDARD

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1 ENERGY SUSTAINABILITY BY THE PASSIVE HOUSE STANDARD Anna Bac Dr inz. arch., assistant Faculty of Architecture - Technical University Wroclaw Wroclaw, Poland Dieter Brandt Dipl.-Ing. IntegerProject Dresden-Radebeul, Germany 1. Introduction: No Sustainability without Energy Sustainability We would like to speak about sustainable housing instead of sustainable buildings, because housing is by far the main part of the life cycle of a building. Generally speaking the energy demand of housing in now common buildings is more than 95% of the total energy input from their construction to their demolition. Strongly defined and clearly spoken: Sustainable energy supply for space heating and hot water preparation is only possible on the basis of rene wable sources like solar energy and bioenergy, also, in case of the usage of electricity for heat production. The usage of natural gas, oil and coal as well as electricity from fossil sources causes global warming with its catastrophic follow-up now already appearing in storms and floods of higher frequency and greater extent. They give us an idea of what is coming. Additionally, fuels and electricity from fossil sources are not durably available. Our present task for achieving energy sustainability of housing is to speed up switching to renewable energy sources! One obstacle is the higher price of energy from renewable sources. We can accelerate the transformation if we introduce buildings with extremely low energy demand. The issue at hand are not the energy prices from renewable sources but the additional costs for the transformation. They get payable quite independent from the price of the

2 energy supply if their amount is insignificant in the household costs because of the energy demand being close to zero. Our good news for this conference is: Demand reduction down close to zero is possible! The Passive House enables warm housing without nearly any energy for heating. Together with the fuel demand it reduces the emissions (not only of CO 2) down to between one quarter until one-tenth (both for new buildings) in comparison to good national standards of heat loss protection in Europe (without switching to energy from renewable sources). 2. What is the Passive House Standard? A Passive House is so thickly and correctly insulated (outside walls, windows, roof and ground) and so well tightened (against convection, not against diffusion!) that the energy consumption for heating decreases close to zero, to < 15 kwh/ m²*a in Central Europe. The passive energy inputs: Heat from the inhabitants, solar energy through the windows and the waste heat from the electric devices provide the essential contribution (2/3) for covering the heat losses of the building. Only the rest is heating [1]. The thermal living comfort improves. Also, the air quality in the building increases due to the ventilation system. The Passive House principle was developed by Dr. Wolfgang Feist, formerly at the stateowned Institute for Environment and Housing (state Hessen in Germany), now director of the Passive House Institute. The 15 kwh are related to the area used within the thermal shell for residential purposes. What the thermal shell is will be explained later. There is a side criterium: The demand for primary energy of all energy usage in the building is limited to up to 120 kwh/m²*a at standardised energy use for electric appliances and at standardised energy losses for hot water preparation within the thermal shell. Primary energy is energy found as fossils or uranium in the underground. This prevents that low effective electric devices and bad insulation of equipment for hot water preparation plus distribution replace heating energy to a higher extent than set by the standard.

3 3. Passive House Essentials 3.1 Overview There is no specific additional and no specific active element for providing more energy to the building. Therefore, the houses are named Passive Houses. The Passive Houses have only the same elements as used in any ordinary house, but of better quality and better co-ordinated, controlled and managed by the planning tool: the Passive House Planning Programme. What must be better, by necessity, in Passive Houses? 1 Insulation 2 Tightness 3 Windows and 4 Ventilation. Table 1. Characteristics of the main features of the Passive Houses 1 Insulation of the outside walls, the roof and the base: A closed thermal shell with increased thickness of the insulation. Thickness of the insulation of the outside walls of new buildings: Outside walls after thermo-modernisation of existing buildings: Preferably without heat bridges with the heat bridge coefficient: U< 0,15 W/m²*K Min. 30 cm thick at?= 0,04 W/m*K Min. 25 cm, depending on the climate region ψ< 0,01 W/m*K 2 Tightness against uncontrolled convection: Shell at/in the outside areas of the building, tight against convection but open for diffusion provided by diffusion open folios or reinforced cardboard. Air exchange rate in the blower door test at 50 Pascal pressure difference in both directions: n 50 < 0,6 h Windows and outside doors with the best available heat loss protection. Glass: 3-fold with mirror shifts and gas between the panes. Frames: Super-insulated. Energy inlet rate of the glass: Ventilation unit with heat regain Volume stream (Input = Output): Effectiveness of heat regain: U w(glas+frame) < 0,8 W/m²*K g>/= 0,5 30 m³/h pro Person > 85% The register of the formula characters may be found at the end of the paper.

4 3.2 The Thermal Shell This is the closed insulation of all exterior areas (outside walls, ground and roof). It has to be free of interruptions and preferably without heat bridges, like a heavy sweater! For the thickness of the insulation of the outside walls see Table 1. The thickness of the roof insulation can be approx cm and 40 cm of the base insulation. The thickness of insulation is subject to an optimisation process by the Passive House Planning Programme. Co-ordination with the parameters of other elements like quality, direction and size of windows, and the effectiveness of the heat ventilation regain unit etc. is necessary. Free of heat bridges means: The heat bridges cause an additional heat loss of less than 0,01 W/K (= 0,35 W at Delta t =35 K) for point heat bridges and of less than 0,01 W/K (= 0,35 W at Delta t =35 K) on a length of 1 m for the linear heat bridges. Figure 1. Both of the shells of a Passive House. The thermal shell (yellow) and the convection tight shell (red) Figure 2: Insulation with mineral wool, 30 cm thick 3.3 The Convection Tight Shell The convection tight shell (CTS) consists of diffusion open folios or reinforced cardboard pasted together with adhesive tape or a special glue. On the outside walls of new houses the CTS is the internal plaster with the airtight casings for electric switches, distributors etc., or they are made airtight with adhesive paste. Each passage of cables or pipes going through the convection tight shell has to be made airtight. All folios (or cardboard) that are to be connected to the walls or to the ground must be attached by adhesive paste. Likewise, the window frames must be attached to the walls. Hereby, close attention must be paid! The proof of the success of all efforts made is the blower door test at the end of the raw construction phase. The air exchange rate has to be lower than 0,6 at a pressure difference of

5 50 Pascal in both directions. The tightening activities have to be continued until this result is achieved. Figure 3. The leakage streams into the house during the blower door test Figure 4. The blower in the door during the test 3.4 The Passive House Windows The high tech of the Passive Houses is in the windows. They have to be certified by the Passive House Institute. Otherwise, we cannot ensure that the Passive House will have the energy demand as calculated. Where else would we obtain the guaranteed parameters for the calculation? For later our aim is the Passive House windows to be produced and certified in the countries where they are used. We look for production partners in the window industry and for neutral national transfer and consultation centres, which will be qualified for certification. The windows consist of three main elements: Glass, frame and draught excluder. Some details are mentioned in Table 1. The max. value of 0,8 W/m²*K for U w can be achieved only with the U g for glass of max. 0,7 W/m²*K. The special 3-fold glass with mirror shifts and gas fill-in of the spaces between the panes are commercially available as well as the complete windows now, even those made only of wood! The best windows are the double windows made according to old patterns as shown in the following figures. Passive House windows have a positive energy balance throughout the year if they have their exposure from the south to the west or to the east. Their area in these directions has to be large enough to provide enough solar energy for the passive house during the heating period, but small enough to prevent overheating of the building in summertime. The Passive House Planning Programme can control this optimisation. The windows from north to west and north to east should be as small as possible.

6 Figure 5. Double Passive House windows System Leipzig with Uw =0,68 W/ m²*k Figure 6. The window doesn t need any prote ction facility against overheating in summertime The cross section of a simple Passive House window is shown in the following figure: Figure 7. Cross-section of a Passive House window with the isotherms. The window is correctly assembled into a wood construction wall In the following picture you can see the influence of the Passive House design onto the size of the windows in the southern facade. A large increase in the size of the windows was

7 necessary for developing a Passive House from the traditional rural design protected by the regional administration. Figure 8. The increase of the area of the windows in the southern facade for achieving the Passive House Standard creates an improvement of the architecture In this picture, thermal solar equipment with a collector area of 16 m², feeding the central storage containing 800 l heating water, supporting the hot water preparation (by 70 %) as well as heating (ca. 50 %), can be seen. This is a good addition to the windows and makes easy switching to wood as a fuel for the yearly rest heating demand of about 7,5 kwh/ m². 3.5 Ventilation with Heat Regain Because of the high-grade tightness of the buildings, the leakage rate through the exterior areas is very low and the air input and output are compelled to go through the ventilation device and the heat exchanger between the input stream and the output stream. Its heat exchange rate should be higher than 85 %; the best devices have more than 90 %. During the heating period it is not necessary to open the windows. The Passive Houses always have clean air because of the controlled air exchange and the inhabitants lose the feeling that the windows need to be opened. This is the experience of thousands of Passive Houses and flats used and also the experience of the passive house of my own family. The main positive side effects are: 4. Positive Side Effects of the Passive Houses Improvement of thermal living comfort Excellent air quality in the building 4.1 Overview Prevention of mould, even in the most unfavourable cases Better quality of buildings because of project certification and more intensive implementation control

8 Attention: There is no Passive House without trained planners and certification, trained handicraft people and trained supervisors during the implementation! No air-conditioning system necessary for the summertime, not even for office buildings Heating costs are only % of these for new houses with the actual standard of protection against heat loss and most of all: Easy switching to energy supply for the rest demand from renewable energy sources. 4.2 Thermal Living Comfort The thick insulation provides high temperatures (min. 19 C) on the internal surface of the outside walls. This gives a warm and pleasant feeling to human skin. The windows with the large glass areas are also warm (min. 16 C), even if there is no sunshine. The cold fall-down of the natural air ventilation from the windows no longer exists. The radiators of the heat distribution system are small because of the low energy demand and do not have to be located below the windows any more for preventing the cold air fall-down. The whole house within the thermal shell has nearly the same temperature. If one room, for instance the be room, is to have a lower temperature, then it is proposed to plan and perform the thermal separation for this room. But it is not necessary. Calculations have shown that an open window in one room at night during the winter period increases the key figure, yearly specific energy consumption per m² residential area within the thermal shell, by about 3 kwh/ m². 4.3 Easy Switching to Renewable Energy Sources According to our opinion this is no side effect but the goal of the effort. How easy it is, can be seen from the following very rough calculation: The rest energy demand for heating of one Passive House residential unit is max. where: (60 m² * 15 kwh/ m²*a) /η = 1125 kwh/a fuel η - Efficiency of energy transformation from the fuel into the heated rooms taken as 0,8 for modern facilities. The rest energy demand for hot water preparation to one Passive House residential unit is max. where: (1,5 kwh/(person*d) * 365 d/a * 3P)*0,5 /η = 990 kwh/a fuel, η - Efficiency of energy transformation from the fuel into the hot water taken as 0,8 for modern facilities % of the energy demand of the hot water preparation is covered by the thermal solar equipment. For the sum - heating and hot water preparation - are necessary: ( ) kwh/ H u = 490 kg wood (as chips, pellets etc.) during one year,

9 where: H u Heat content of the fuel. In the case of naturally dried wood it is 4,3 kwh/kg. This amount of wood can sustainably grow in an area of energy forest of where: 490 kg*a/ E = 0,05 ha = 500 m², E = kg/ha*a sustainable yield of an energy forest. For this purpose, only 0,05 ha * 10 Mio = ha are needed for approx. 10 Mio residential units in Poland. Including possible reducing factors, this will not be more than ha. 5. Additional Investment Costs of Passive Houses Leaving aside investment costs, this speech will concentrate on the full housing costs. Nevertheless, a comparison of the investment costs of 9 Passive Houses built with all in all 250 flats in Sweden, France, Germany, Austria and Switzerland to houses built according to national standards has presented additional investment costs of only 8 % [2-4]. As long as some key elements have to be imported, this amount will be higher in the CEE countries. This is also due to the lower base costs. This comparison is a reliable base for providing a successful economy for Passive Houses, also in the CEE countries. 6. Conclusions The Passive House Standard is not protected. We would like to encourage every administration (national, regional or communal) to introduce the Passive House Standard for ensuring survival during the coming period without uranium, oil and natural gas. This lecture is to help house owners not to feel compelled to go back to hard coal and its follow-up products as the only long-range fossil energy source which would double the CO 2 emissions! Not depending on the implementation as the legal standard, everybody is invited to use the experiences made in Germany, Austria, Switzerland, Denmark and Sweden and to apply the Passive House planning tools and the Passive House technologies for achieving the Passive House Standard in new buildings and to reduce the energy demand by thermo-modernisation down to the limit which is double the one for new houses. This is not unrealistic. The authors offer their consultation, experiences and facilities.

10 7. Register of the Formula Characters Unit Definition U W/m²*K Heat transmission coefficient of an outside area: The heat stream in W, which goes through 1m² of the outside area, if the temperature difference between the internal and external space is 1K U w W/m²*K Heat transmission coefficient of the windows or outside doors: The heat stream in W, which goes through 1m² of the whole of the outside area for the window, if the temperature difference between the internal and external space is 1K? W/m*K Heat conductivity of a construction material: The heat stream in W, which goes through 1m² of the area of a test piece with the thickness of 1 m, if the temperature difference between the both sides is 1K n - Air exchange number: The air stream in m³/h related to the internal volume of the building? W/m*K Heat bridge coefficient of a linear heat bridge: The heat stream in W, which goes through the heat bridge with a length of 1m, if the temperature difference is 1K? W/K Heat bridge coefficient of a point heat bridge: The heat stream in W, which goes through the heat bridge, if the temperature difference is 1K - Solar cover rate of a thermal solar equipment: The share of the energy supply of the solar equipment in the energy demand. 8. References [1] Feist W., Gestaltungsgrundlagen Passivhäuser (German), publishing house Das Beispiel, Darmstadt 2001, pp. 7 and 62 [2] Krapmeier H. and Drössler E., CEPHEUS Living Comfort without Heating ( in German and English), Springer Wien New York 2001, ISBN This book is the official final document of the project CEPHEUS (Cost Efficient Passive Houses as an European Standard) Austria , supported by the EU Thermie programme (BU/0127/97) [3] Feist W., Peper S. and Görg M., CEPHEUS project information no. 36: Final Technical Report (in English), enercity/stadtwerke Hannover AG 2001, delivery by [4] Feist W., Peper S. and Görg M., CEPHEUS project information no. 38: Final Publical Report (in English), enercity/stadtwerke Hannover AG 2001, delivery by

11 7. Contact Partner in Poland Dr arch. Anna Bac Faculty of Architecture - Technical University Wroclaw Tel./fax: anna.bac@pwr.wroc.pl JACO, Osrodek Oszczedzania Energii Arch. Agnieszka Cena, Tel.: , agcena@cieplej.pl Internet: 8. Contact Partner in Germany IntegerProject Dipl.-Ing. Dieter Brandt Tel.: , Fax: brandt.consultant@t-online.de Internet: and