Passive House Report By Axle Von Garde Cabahug Shahidah Syedah
Interior Systems and Circulation 221-530-VA Section 00003 Elizabeth Anne Thorp 12.03.2015
TABLE OF CONTENTS Introduction
What is a Passive House?
The Three Heat Transfer
Passive House in Hot Milieu
Passive House around the world
Application of the Concept
Fire Hazards in Passive House
2 03 04 6 06 7-9 10 11-12 013 4
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Passive House in Cold Milieu
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Passive House Retrofit
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Conclusion
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INTRODUCTION
In the late nineties, a new way of building homes was discussed. This idea hoped to change the point of view of house designers. That is the Passive House (Passivhaus in German). The Passive House began as a method of decreasing the energy utilization in homes. This complex system possesses distinctive strategies to lower energy utilization. These houses are likewise exceptionally made to warmth/cool oneself in order give comfort to the users and guests of the house while utilizing a considerable less energy usage than an average house. The advancement of these houses could help our planet by sparing a ton of energy that would be made by ways that can contaminate our planet. In order for a house to be considered a Passive House, its must achieve the set principles for the utilization of energy and air tightness. The Passive House measures are exceptionally strict in regards of the codes relating to energy use. With such challenging norms, the house advantages its holders with lower cost on the use and environmentally friendly. Passive Homes do have a blemish: they are more expensive in terms of applying. In that case, future research will help manage the cost of applying this design; make the concept more affordable or cheaper. Furthermore, trials will be made to open the Passive House design into the world of business. With such innovation nearby, we could perhaps discover different approaches in designing homes to lessen the measure of contamination tossed all around our environment, making a finer state of living for humans, animals and other living organisms on the planet. This report is in view of distinctive sorts of Passive Homes; how Passive House design varies in different regions, the different standards in a Passive House designs and their impact on the environment. Although, most of all, this report will show how this system can achieve creating functional houses with very low consumption of energy.
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WHAT IS A (Passivhaus PASSIVE HOUSE? in German) The Passive House (Passivhaus in German) system was first mentioned by Bo Adamson (of Lund University, Sweden) and Wolfgang Feist (of the Institut für Wohnen und Umwelt) in May 1988. The concept of these two men was produced through various trial and error projects and as for the financial aspect of the project; they received aid from the German condition of Hessen. The idea of the Passive house speaks today's most elevated energy saving norms on the planet. It diminishes the energy utilization of an ordinary home by around 90% while keeping the same degree of contentment. If the Passive House design concept were applied world wide, it would have a sensational effect on energy preservation. According to the U.S. Energy Information Administration, regular buildings like we have today are in charge of 40% to 50% of all the greenhouse gasses radiated every year and 76% of all power created by U.S. force plants goes to supply the Building Sector. Therefore, sadly, this somewhat proves that the buildings in our surrounding are generally to blame for the climate change. In the battle to lessen energy utilization, Passive House design is an exemplary choice to enhance the circumstance. A part of the methodology of a Passive House is to reuse the heat already being generated in the house. This refers to the warmth being generated but the electrical and gas machines in the house. (I.e. broilers, coolers, PCs and lights) Furthermore, the skin of a Passive House must be greatly and decently insulated and airtight in order to prevent unwanted air exfiltration and infiltration. What most Passive Houses have in common is that they are heavily insulted. They go with criteria of R-40 to R-60 for the walls, R-50 to R-90 for the roof and R-30 to R-50 for the ground slab. Furthermore, most of these houses possess triple glazed windows with a Low-E coating and their method of designing and constructing remarkably avoid thermal bridge, unless if its a wood frame construction. According to The Building Science Corporation the essential Passive House norms are: • Airtightness of 0.6 ACH@50 Pa or less • An aggregate warming & cooling interest of <15 kWh/m2/yr. • Total essential (i.e., source) energy of <120 kWh/m2/yr
Bo Adamson
Wolfgang Feist
<= 0.6 ACH@ 50 Pa
Airtightness
<15 kWh/ m2/yr
Aggregate warming & cooling interest
<120 kWh/ m2/yr
Total essential energy
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H O W PA S S I V E H O U S E WORKS IN DIFFERENT CLIMATES When it comes to Passive house designs, architects take advantage of the different ways of transferring heat; conduction, convection and radiation.
Conduction
Conduction is the way heat travels through materials when there’s a difference in temperature, making a trip from molecule/atom/ particle to another. For instance, if you were to submerge the tip of a spoon into hot water and wait for a couple of second, the tip of the spoon would be hotter than it used too. If applying this heat transfer on building design, building envelope materials suffer conduction heat gain and loss when there’s a difference in temperature. If the indoor temperature is higher than the outdoor temperature, there’s a heat loss from the outdoor and a heat gain from the indoor of the building. Typically, heat gain and loss happen on windows, wall and roofs of a building. As a result, architects take advantage of this to heat the building. For example, houses are oriented a certain in order to maximize the building’s exposure to the sun; the point when the sun warms the windows and exterior walls the warmth goes by conduction through the openings and walls within the house which leads to warming the house.
Convection
Convection is the way warmth flows through fluids and gasses. This generally explains why hot air rises and cool air goes down; while cooler, denser liquids sink lighter, hotter liquids rise. Be that as it may, within a typical house, twenty percent of the warm air escape through the walls and under the house, thirty-five percent goes out through the openings and forty-five percent is released though the roof. Furthermore, some Passive Homes utilizes air convection to distribute solar heat around the building. Stack Effect or Chimney effect is an example of a common occurrence within buildings. Resulting from buoyancy, it is characterized by the movement of air into or out of a building. Buoyancy, however, is caused by the air pressure difference between the outdoor and indoor environment (which either results a negative or positive force). The stack effect is affected by the thermal difference and the height of the building, because a greater temperature variation and a taller building results a stronger buoyancy force. Furthermore, the stack effect is taken advantage of in Passive House designs, because it helps with the natural ventilation.
Radiation
Radiation is the means by which the warmth travels through the air from hotter conditions to cooler ones. At the point when radiation comes in contact with an item, it is ingested, reflected, or transferred, relying upon specific properties of the material. No transparent materials generally absorb forty to ninety-five percent of the solar radiation depending on their colour; lightly coloured materials absorb a lot less solar radiation. With that being said, in the Passive House design, architects tend to use solar panels with very dark hues in order to maximise the absorption of the solar heat.
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PASSIVE HOUSES IN COLD MILIEU Thermal mass and windows are the fundamental materials to warmth up a Passive House. The most straightforward approach to warm a house would be that the windows ingest the warmth from the sun into the house and warm the house. However, the atmospheric conditions never stay the same. Just like how during summer, since the sun is up for a longer duration and is stronger than some other time in the year, houses tend to be warmth excessively. In contrast, during winter, even though the sun doesn't stay out long and it isn't as solid as in summer, the solar heat being radiated is sufficient to warmth the house. As a result, the essential action to make is to protect the upper portion of the window (Head) from the sun at its highest point. Therefore, during the day, as the sun rises, the house is digesting the heat, but when the sun reaches its highest peak, the window is protected and this prevents the house form overheating. The thermal mass in the house assimilates the warmth that the windows have engrossed in from the sun and preserves it. Later on, when evening falls, this warmth is then discharged and the temperature drops. .
This is simply the approach to warmth up a Passive House. There is however a necessity to have a steady measure of air flow, for it would be exceptionally uncomfortable for the holders to breath the same air throughout the day, particularly since there might be some unwanted “odor” in the house. A Passive House needs to have an energy recuperate ventilator in order to forestall uneasiness. This is a unique ventilation framework where the air from outside is warmed and taken in while the air inside is removed to the outdoor. This network is exceptionally straightforward; it needs the warmed air in the house, a sun powered controlled radiator and the outdoor air. Essentially, when the air from outdoor is streamed into the house, the sunlight based fuelled radiator warms the air. On the off chance that the heater is insufficient, the building will still be warmed properly in light of the fact that the outdoor air will then be absorbed by a mechanical heat exchanger, which will then warm the outdoor air before its discharged. This then causes the exterior air to be at just about the same temperature as the air inside the house thusly managing the warmth from the removed air. Furthermore, an ordinary house generally wastes ninety percent of its energy on heating itself. As result, all through this entire framework, the house needs to be essentially air impermeable, meaning airtight. In most cases, due to convection or Stack Effect, the air escapes from the rooftop since warm air rises. Although it might also find its way out through the gap below doors, the windows, the exterior and foundation walls, the floors and the ground slab.
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Bref, the Passive House system do oblige their house designs to be airtight in order to conserve the energy used to warmth up the house, which will then lead to as an inexpensive house to live in. When it comes to designing homes, in general, architects would rather have the conditioned air taken from the outside to be distributed into spaces where it is needed. As a result, in most cases, the conditioned air is streamed through living room and bedrooms and is discharged through kitchens and bathrooms. When the air infiltrates and travels through the house, it manages its way to the kitchen and bathroom and will then escape with all the odors. Additionally, There is other option path for the house to be warmed. This incorporates a Subsoil Heater Exchanger. This mechanical equipment replaces the solar panel and as opposed to warming the air with sun oriented force; it warms the air with geothermal energy. At the point, as opposed to being warmed by the sun powered boards, when air is distributed into the house, it gets warmed by running underground due to the geothermal energy present right under the house. This way of heating a house isn’t more lavish than using the sun (solar panels). However, since the ground is always warm, the house is heated all year long, which can potentially cause excessive distribution of warm air and discomfort to the users of the building.
PASSIVE HOUSE IN HOT MILIEU Utilizing materials that confine the cool air inside the house and a straightforward air circulation system are two regular approaches to keep a house cool as the year progressed. Materials like hay and clay are magnificent cases of materials that preserve the air inside the house refreshing for the users. With a these two materials, it is possible to create a mass that is “stocky” enough to prevent air from escaping and tense enough to have a very low thermal conduction. However, since not all houses can be built with these materials due to the different climates, to cool a Passive House located in a hot weather condition, the building must be properly insulated. Just like the Passive Houses in cool climate, there is still the arrangement of ventilation. However, the energy from the sun-powered boards is transformed into energy that will help with a proficient network of cooling instead. As a result, on days where the sun is not “active”, the house will stay cool and when the sun is shinning, the daylight gives vitality to cool the house. Having a small Opening on the top of the roof of a house can also help with the cooling process. The explanation behind that is that hot air rises due to convection (aka Stack Effect). The size of the opening must also be taken into consideration since we aim to prevent rainwater penetration within the building. The way this works is that, the cool air within a house remains at the base while the hot air finds its way to the highest peak of the building. Furthermore, as the hot indoor air reaches the highest point of the building (generally the roof), it escapes through the opening. However, this network of convection may only be applied on house with “pointy roofs”, because, otherwise, there’s a possible excessive amount of cool air escaping from the building. In this framework, since the roof is the only part of the house that leads the air escape, a ventilation system must be installed. As a result, the other area of the house is properly insulated. Additionally, id is required to have a filter on the summit of the roof to be assured that no cool air escapes form the building; a great way to save the conditioned air used in the house.
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PASSIVHAUS IN DIFFERENT REGIONS OF THE WORLD Each continent has its own characteristics culturally, economically, politically, etc. In the case of this concept, the geographical of a building has a major influence on the different methods used to be considered for a Passivhaus Certification. Quebec’s weather is extremely variable. Montreal, which is located at the south of the province, can reach a high of 36.1°C in the month of July and a low of -33.5°C for the month of January. If we compare this to Kuujjuaq (Nunavik, Quebec), which has registered a record low temperature of -49.8°C, we know that the R-Value, which is the resistance to the transfer of heat, will definitely differ from one another. In the previously mentioned northern village, there will be a lot of more energy needed to heat a house; consequently, the R-value of the different components of a building envelope will be significantly higher than the one in Montreal, for it to satisfy the Passivhaus standards. In fact, this issue needs to be addressed and taken into consideration when building houses based on this concept. This problematic was seen in the United States when they were building houses using the European Standards of the Passivhaus. In Florida, houses were s e e n to b e o v e r i n s u l a te d a n d o v e rg l a ze d w h i c h re d u c e d t h e
1Construction
effectiveness of this type of construction. For example, a lot of money is spent on high-performance windows that have multiple layers of glass to provide a better resistance to the transfer of heat and cold between the indoors and the outdoors. However, in a hot and humid climate of this American state, the maximum heating and cooling demand of 15 kWh/m² established as a Passivhaus standard is not achievable when taking into consideration the building envelope as a whole. In the following paragraphs, we will explore the standards imposed by the Passivhaus Institute in Germany compared to the ones at Canadian and international level, as well as some examples of this construction. Here are some of the standards established for Germany: • Passive Solar Gain1: Optimized south-facing glazing (Satisfy 40% of heating demand) • Window Glazing 2 : Low-E triple glazing (U-value ≥ 0.8 W/(m²K) = R-Value ≥ 7.1) • Window Frames: (U-value ≥ 0.8 W/ (m²K) = R-Value ≥7.1) • Walls: U-value ca. 0.1 W/(m²K) = R-Value ≥ 37.85) • Airtightness3: Less than 0.6 air change/hour at 50 Pa pressure difference
that uses the natural energy of the sun to heat and cool the interior without much maintenance and use of mechanical equipment. to the glass used on windows, doors, etc. 3Resistance of the building envelope to holes or any other forms of leakage that can cause air to move inside a building and out of it 2Refers
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Quebec, Canada In Quebec, many certifications are available such as Novoclimat which has been used for more than 15 years in Quebec. As for the Passivhaus with its more rigorous requirements, it has only been used in the province for the past 2 to 3 years. Even it hasn’t been tasted specifically for the Quebec climate; we can have an approximate idea of the standards that are required for a house to be fully functional under the Passivhaus Institute. In the table called “Properties of the functional Passive House in Jekaterinburg.” Located in Russia, we can establish a relevant comparison with the province of Quebec due to similar climatic statistics. If you compare the values in the chart with the ones mentioned previously, you can see that they surpass the requirements of in a German geographical context. A research conducted and published by the Université de Sherbrooke helped established a more precise overview of the suggested properties of a passive house. For example, the thickness of the insulation should be between 40 to 80 mm, the R-Value for the window frame should be of at least R-8.47 and the one of the window glass should be of at least R-11.13. According to the same research, Écohabitation has revised the required insulation of the building envelope, mainly the wall and the roof. The Passivhaus Institute has established a minimum requirement of R-37.85 for the insulation, but in Montreal this number is of R-51.6 for it to be satisfactory. For example, in Montebello, Québec, a passive house was built well beyond the minimum requirements. With its wall framings composed of a 2”x6” followed by 16” of stone wool insulation and completed with a frame of 2”x4”, an overall R-value of R-65 was established. As for the roof of R-82, there are 21” of the same type of insulation with an 12” air cavity. The foundations were made out of Insulated Concrete Forms (ICF), where the walls are poured and formed around a formwork of two layers of polystyrene insulation. Finally, the airtightness of the house was of 0.36 airchange/ hour @ 50 Pa of pressure difference.
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Doha, Qatar In the case of a country located in the southern hemisphere that is not exposed to winter, major differences can be seen in this concept. As mentioned earlier, houses in hot climate tend to distinguish and have different needs than the ones in cold weather. After exploring the unique climate of a Canadian province, it is essential to analyze Qatar’s usage of the Passivhaus. Located in the Middle East, this country characterized by a hot desert climate uses a much different construction method. In fact, as you can see in the image on bottom of page 10, there is no foundation wall used. In addition, wood is not a material that is abundant in Qatar; for this reason, masonry was used. With respect to the standard construction method used in Qatar, the size of the masonry units are increased by 100 mm and the air cavity of 50 mm are removed.
Also, by using the 37 cm of polystyrene thermal insulation that wraps around the whole building envelope, the bituminous paint that is normally used to create a separation between the compacted soil and the concrete foundation slab is removed. By doing so, the original purpose of the Passivhaus which is to retain heat indoors is replaced by a concept that intends to keep the cool air indoors. Under an extremely hot and humid climate, heat gain and natural lights are controlled using small triple-glazed windows and skylights which are covered with a highperformance coating.
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PASSIVE RETROFIT Reusing and recycling materials for the environment are always techniques that could improve the ecological footprint of an individual on earth. In the case of the Passivhaus concept, other than applying it to new constructions, existing homeowners who wish to improve its energy consumption and reduce its heating and cooling bills are able to do so as well. This certification is known as the EnerPHit. Due to the fact that it is rather impossible to prevent thermal bridging in a basement after it is built, the requirements are a lot more flexible. For example, the maximum heating and cooling demand is known of 25 kWh/m² instead of 15 kWh/m². Also the air tightness is now limited to a maximum of 1.0 airchange/hour @ 50 Pa of pressure difference.
A house built by Barry Byrne, former employee of Frank Llyod Wright was submitted to a complete renovation. Being built in the Brutalist period, it is characterized by the use of geometrical forms and concrete. Indeed, this material is known to create major thermal bridging in a house, which would reduce the overall air tightness. A solution to this problem was created by two passive house consultants, Ken Levenson and Gregory Duncan. They’ve decided to wrap the entire residential building in insulation. It consisted of a 10” fireproof and inert Styrofoam liked insulation made of recycled glass. As you can see in the image of the wall composition, an air barrier is installed to prevent air leakage. Together, they helped reduced the thermal bridging. On top of this, the windows were removed and replaced with modern ones, which satisfies the energy saving.
Some identical standards can be seen. It is the case for the elements that can be removed without requiring major work that would make the house still livable. For example, the windows and doors opening, the standards remain the same at minimum UValue of 0.8 W/(m²K). These modifications considered rather essential and act like requirements do, in fact, have some exceptions. In the case of a historical building under preservation authorities, an elimination of the cost-effectiveness, or a presence of a legal constraint, these standards can be neglected.
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APPLICATION OF THE CONCEPT Offices in Germany New constructions of a b u i l d i n g s e r v i n g a re s i d e n t i a l occupancy are not the only one that benefit from this rather complex system. In fact, other occupancies of the National Building Code can be submitted to these standards. In this section, we will explore the Group D Occupancy of the code, such as offices. Offices have different considerations than the residential occupancy of a building. Since many people will be present and will be working on computers, a lot of lighting is generally used even in the daytime. For this reason, the internal heat of an office space is significantly higher than the ones in a house. Consequently, it is important to determine the number of openings to prevent overheating from occurring, while allowing solar gains during a colder time of the year.
In this chart published by the German Passivhaus Institut, we can see that in a normal office building that uses air conditioning there is a total usage of 225 kWh/m² compared to a total of 67 kWh/ m² in the rather energy efficient one, the expense in energy is nearly 3.5 times lower in a Passive office building. The major differences are the lighting, the air conditioning and the heating. Again, in this comparison, we see the effectiveness of applying this concept in buildings. In addition, the use of more efficient lighting, such as a dominant use of natural light as well as computers that consume much less energy can reduce the overall energy usage by nearly 7 times. The heating and cooling demand of 15 kWh/m² was surprisingly followed in the Passive Office Building. In conventional German office buildings, this number has reached a lowest value of 68 kWh/m², and on average, it is at 93 kWh/ m².
Unlike homes, office spaces are mostly occupied only during the day. Therefore, to comply to the reduced energy consumption required by the Passivhaus concept, the mechanical system has to be designed to provide a comfortable atmosphere during the day and at night, when everyone is gone, the ventilation decreases. This can be done using a CO2 sensor.
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A clear distinction has to be made. The rigorous standards do not act as a limitation on vertical constructions. In other words, it does not only apply to only low-rise constructions of office buildings. In 2013, the Raiffesen-Holdings Hochhaus Office Building was c e r t i fi e d b y t h e Pa s s i v h a u s Institute’s branch in Austria. It has 20 storeys and mesures 80 m in height.There are many main components that would distinguish this skyscraper from its conventional model that are regularly built in major cities throughout the world. There are 3 characteristics: • Well-insulated double facade • Use of daylight • Advanced mechanical systems.
Furthermore, sensors are present to detect the occupancy and brightness for a better economy in light and cooling demand. As for the mechanical system, the heat generated by the servers that helps maintain the full functionality of the computers are distributed elsewhere. Consequently, in the winter, this building does not need to spend money on additional heating. As shown in the graph below, the data center’s waste heat represents more than 38% of the heating needs of the Raiffesen-Holdings Hochhaus tower. With an additional cost of 3.6 millions $ compared to the standard type of office buildings; this amount is expected to be fully covered in around 14 years through the 80% in energy savings.
The doubled glass curtain walls along with 60 feet of building width contribute to the natural heating of the floors. In fact, the issue of overheating is fixed by a shading system located in between the cavity of the first and second layer of glass. This system is designed to be operable by the occupants of the space based on their personal preference. Also, instead of air conditioning, operable windows at the inner layer of the building envelope help improve the overall ventilation of the office area.
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FIRE HAZARDS IN PASSIVE HOUSE One of the main dangers of a building is fire. Storing various electrical equipment and providing a space for humans, constructions must take into considerations the safety of its occupants. The airtightness of a building built based on the Passivhaus concept is often thought to be submitted to a higher risk of fires. Because it traps the air inside the house, in the case of a sudden increase in oxygen level after sudden break of the openings, this introduction of oxygen mixed with the burning flames may cause explosions. This is called “Backdraft”. In a research conducted by the University of Mons located in Belgium, the fire in a passive house starts to lose its strength at 300 seconds due to a lack of new air. The temperature also does so. On top of this, if ever a layer of the glass fails, the three layers in the windows will, nonetheless, provide additional safety. Due to the air tightness, the temperature is quickly reduced at a constant rate as we can see in the lower graphical representation, unlike the traditional house that continues to increase its temperature for about an extra 300 seconds. Under the same circumstances, a higher accumulation of combustible smoke may occur since air is be trapped indoors. However, it is not typical of a passive house construction, because no scientific proof has been established and no incidents of this type have occurred. Therefore, it would be unrealistic to attribute such fire hazards to distinctive type of construction technique.
Also, one must not attribute this lower temperature to the increased amount of insulation placed in a passive house. The research determined that there were not particular link between the thickness of insulation placed and the temperature of the flames. The only factor that would increase the fire hazard is if combustible insulation is placed as a wall finishing. With a lower transfer of heat, the temperature was at 560°C instead of the 350°C for a covering of gypsum wall board. Bref , it is imortant to know that it is the Passivhaus properties does not propagate or start a fire; it is rather what is inside the house, such as the furnitures and appliances that would contribute to a higher risk of fire.
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CONCLUSION More or less, houses built with the Passive House standards attempt to lessen their energy utilization as low as could be under any circumstances. This is done by properly insulating the house and by setting a point of limit, which is reasonably low, to the amount of energy they can utilize throughout the span of one year. The Passive House system also aims to reduce the toxic substance being released by houses since it’s generally the common source air contamination. In order to reduce the negative effect on the environment, this system reduces the energy consumption of houses; it is done by reducing the demand of houses for energy. Subsequently, if the number of houses that needs high amount of energy decreases, less power will be produced, which results a reduction of air pollution. Furthermore, Passive House designs oblige a complex ventilation framework and an airtight house. Consequently, this makes the house a lot more expensive than ordinary houses, although it is guaranteed that, on the long run, Passive Houses costs a lot less to be functional. In spite of the fact that these houses help a great deal on the environment, the reason that the world does not have a greater amount of these houses is generally because the people aren’t yet ready to change their way of living and/or blinded by the initial cost of building a Passive House.
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BIBLIOGRAPHY
Quebec • http://www.politiqueenergetique.gouv.qc.ca/wp-content/uploads/ 2015/02/EE_20150212_002_Marie_Eve_Robinson.pdf • http://ici.exploratv.ca/blog-explorateur/le-monde/maison-kenogamimiracle-defficacite-energetique-climat-nordique
World • http://www.banrepcultural.org/sites/default/files/ hernandez_andres_dissertation_colfuturo_0.pdf • http://vae.ahk.de/fileadmin/ahk_vae/Startseite_Katar/Energieeffizienz/ 7._QGBC_-_Dr._Alex_Amato.pdfhttp://www.theedge.me/qatars-firstpassivhaus-experiment/ • http://www.esru.strath.ac.uk/Documents/MSc_2012/Gu.pdf Renovation…Convert into Passivhaus • http://www.passivhaus.org.uk/page.jsp?id=20 • http://passiv.de/downloads/03_certification_criteria_enerphit_en.pdf • http://www.treehugger.com/green-architecture/historic-modern-houserenovated-passivhaus-standard.html Passivhaus in Different Occupancies • http://www.ctbuh.org/News/GlobalTallNews/tabid/468/EntryId/5216/ Institute-Recognizes-Worlds-First-Passivhaus-Skyscraper.aspx • https://www.besafe.be/sites/besafe.localhost/files/publicaties/Janec/ MaisonPassive.pdf (Page 5) • http://www.seai.ie/Renewables/Renewable_Energy_Library/NonDomestic_Passive_House_Guidelines.pdf • http://greensource.construction.com/green_building_projects/ 2013/1309-rhw2-office-tower.asp Fire Hazard of Passihauv • http://www.aidic.it/cet/12/26/063.pdf • http://www.lesoir.be/270492/article/economie/immo/2013-06-27/pasrisques-accrus-dans-maisons-passives • https://www.besafe.be/sites/besafe.localhost/files/publicaties/Janec/ MaisonPassive.pdf • http://www.maisonpassive.be/?+Il-y-a-t-il-plus-de-danger-lors-d+ Building Science Corporation • http://www.buildingscience.com/documents/insights/bsi-025-thepassivhaus-passive-house-standard How Does Passive House Work? • http://artisansgroup.com/how-does-a-passive-house-work-4/
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