Arkitektskolen AarhusJanuary 2009Class 2ADTeacher: Helle Christensen

Student: Árný Árnadóttir

The Passive House- house of the future -

Contents

Introduction.............................................................................................page 31.

The passive house concept....................................................................page 3 2.

Basic features.........................................................................................page 43.

Details on main elements.......................................................................page 44.

Explanations why it is expensive............................................................page 65.

Example of a passive house..................................................................page 66.

Summary and conclusions.....................................................................page 87.

References..................................................................................................page 9

1. Introduction

In this paper I will explore the main features of passive houses, i.e. houses which use very low energy compared to standard houses. In particu-lar, I will raise and discuss questions such as the following: What is a passive house? What are the basic features that distinguish a passive house from normal standard house in modern society today? How does such a house work? Why is a passive house so expensive? These questions will be answered below, supported with examples and references. In section 2, I explain in simple words what a passive house is and what it stands for. In sec-tion 3, I give an overview over the basic features of a passive house. In section 4, I give details on how the main elements work. In section 5, I give reasons for why the passive house is more ex-pensive than a normal house. In section 6, I con-cretize the discussion with an example of a pas-sive house built in Denmark in 2008. In section 7, I summarize the main content and conclusions of this paper.

2. The passive house concept

A passive house is a house that uses very low energy but still has the same comfort as any other house. All means are taken to keep the en-ergy cost down, everything from planning the site to home appliances. See Figure 1. The house does not use active heating and cooling system, it regulates the heat by itself. This means that a passive house needs around 80% less heating energy than a building built with today’s stan-dards. A low energy house is not the same as a passive house. A passive house has an even further reduction of energy cost. In some cases it may even be possible to reduce the costs to zero. In spite of all this, living in a passive house is just as comfortable as living in any other house, sometimes even more comfortable. There are so many things one does not need to worry about, compared to living in a standard house. For ex-ample, one never has to open windows for fresh air; the house´s ventilation cleans the air every few hours. The ventilation even filters out external pollution and bad smell , preventing both from

Figure 1. An illustration of the elements of a passive house (See www.passivhuscentrum.se)

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even during a cold winter

Using air to air heat exchanger makes - heat recovery rate over 80%

Solar collectors or heat pumps provide - energy for hot water

Household appliances are provided - with an energy saving function(See Krapmeier and Drössler 2001)

4. The main elements of a passive house

I will now discuss the four main functions of a passive house, the ventilation system, solar gains, thermal bridges and windows, each in a row, before I turn to the reason why such houses are not so common (Section 5).

4.1 The ventilation system The ventilation system is the size of a fridge. It supplies all rooms with fresh air and heat, while at the same time it removes consumed air. Long pipes are installed in ceilings and walls not visible to the naked eye. This is shown in Figure 2. Usually ventilation systems are very loud and dis-

Figure 2. Shows how the ventilation system works. (See http://www.isover.com)

entering the house. One never has to suffer the wait for the radiators to heat the house; after a quick change of temperature outside, the ventila-tion system keeps the house at the same heat level at all times. People living in a passive house do not have to worry about large electric or heat bills, the bill will only be a fragment of the amount regular house owners receive. Passive houses are thus extremely advantagous and are a friend to the environment at the same time. The down side of passive houses is that they are expensive to build, which i will return to in Section 5 below.

3. Basic features that distinguish passive house construction from normal standards today

The exterior of the house is insulated - extremely well.

Walls, ceiling and floor are thicker - than normal, up to 60 cm.

The designing of the house is based - on solar energy considerations as that is a large factor in the passive house concept. Orientation towards south and shades should also be taken into consideration.

Energy efficient window frames are - used.

Air leakage through unsealed joints - must be less than 0.6 times the house volume per hour.

Windows should have a three layer - energy glass.

Fresh air can be brought inside the - house through underground pipes that exchange heat with the soil. The air preheats to a temperature above 5°C,

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turbing. This one, however, has built in sound ab-sorbers which are both more quiet than ordinary ventilation systems and more economic. It even filters out all sorts of pollution so that only clean and fresh air may enter the house.

4.2 Solar gains Sun collectors convert solar radiaton into heat and transfer it to a carrier medium such as water, brine or air. And can then be used to heat water or to help with the heating. The best placement of sun collectors is either on the roof or on the facades. Maximum efficiency

is reached by placing them in a 45° angle facing south and If possible they should be free of shad-ing.

4.3 Thermal bridges Thermal bridges are conductions in buildings, where air from outside can easily enter, thus con-tributing to making the inside temperature cooler. In passive houses much has been done to try to avoid these thermal bridges, because it has been realized that this can severely increase heating costs. These thermal bridges can often be difficult to detect and have throughout time been thought of as either collateral damage or an unsolv-able problem. In the building process of passive houses a reliable method has been developed to detect thermal bridges. By graphically captur-ing the building project, studying floor plans and detailed drawings the thermal bridges become visible and therefore easier to deal with. By using this method, there are better chances of avoid-ing, or at least minimizing thermal bridges. This is demonstrated in Figure 3.

4.4 Windows The windows of the passive house play an ex-tremely an important part of regulating the heat. In cold weather, the triple glazing and thermally insulated frames better resists the cold than the conventional double glazing. On a hot summer day, when the sun shines high on the sky, the triple thermal insulation glazing allows less sun warmth to enter the house, so the house does not overheat. During the winter the low sun shines into the house filling it with warmth. This is shown in Figure 4. If the windows are positioned facing south the heat loss is even less. The following steps must be taken when installing windows in a passive house, to prevent thermal bridges and unnecessary heat loss:

Install 80% of the windows on the - south side.

Place the windows in -

Figure 3. Possible thermal bridges. (See http://www.isover.com)

Figure 4. The three-glazed windows (See http://www.isover.com)

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that over time this concept of houses works. (see Krapmeier and Drössler 2001)

6. Example of a Passive house

Denmark is exploring the opportunities of pas-sive houses and in 2006 three companies held a competition, Middelfart Sparekasse, the house in-vesting company Zeta the house isolation compa-ny Isover. They bought a land for ten houses and invited architect companies to participate. One of the winners was the architect firm +M Arkitekter. See Figure 5. (See www.komfurhusene.dk and www.plusm.dk)

The main goal of the competition was to make a licensed passive house, in a low energy class. Simultaneously the competition organizers wanted the house to be approved by the Danish standards. The demand of the competition was that the house should be fit for a family with three children and the rooms should not be defined as having any particular role, as the plan was to be flexible. The task at hand was not only to design an up to date home, with all modern day demands but also to make a passive house that

the center of the wall of the room.

Cover the frame with an insulating - wedge.

Provide airtight seal joint between - the window frame and the outer wall. (See http://www.isover.com/SiteContent/view.do?navId=15)

5. The reason why the passive houses are not more common

The reason why passive houses are not more common than they are, is all the use of new technology. While technology is new it is also more expensive, but as it becomes more spread and more common it will become more afford-able. Passive houses today are very expensive to build, but very cheap to run. The energy costs are close to none. This makes it very difficult for the common family to afford to buy a passive house, even though it pays off in a few years, since with the low energy cost. Governments in many countries are trying to assist people in finding an easier way of funding the houses by offering to lower other expenses or reduce taxes. These proposals vary from country to country. It is in the governments interest that the concept of passive houses becomes more spread, be-cause these houses help improve the environ-ment by, for example, the use of environmentally friendly energy. That, of course, is in the interest of the whole world since this is an issue that concerns us all. This concept is more spread in some countries than others. Today the main goal of these countries where the concept has established itself is to work on advancing the technology in order to show the world that this house concept works. The best way to do that is by building the houses gradually improving them house by house in order to prove to the world

Figure 5. The passive house designed by +M Archi-tects, located at Stenagervænget 49. (See http://www.komforthusene.dk)

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would meet the needs of everyone, i.e. to make a passive house more advantageous than a normal one. The main architectural idea was a wellknown building type from the twenties and the forties.

See Figure 6. The key concept in such houses was to build rooms of similar sizes around a centered chimney. By us-ing that concept +M Architects

symbolically placed all the technical installations required a passive house in the center. +M Ar-chitects added a chimney to the house, which is something passive houses should be without especially because of the air tightness, which I addressed in section 4.3 above on the thermal bridges. The team at +M made the most original use of the chimney, since it is very traditional in Danish architecture namely, as an exhaust pipe and a window for indirect sunlight. They placed a mirror on the wall opposite to the window, so when standing below it, one can see the sky, quite an attractive element, I must add. This is illustrated in Figure 7.

People opposing the passive house concept have often argued that in a passive house it is not possible to open windows or to have for in-stance your bedroom colder than other rooms. The +M team wanted to find a way to solve this issue, to give the passive house the same flexibil-ity and comfort as other standard Danish houses. Instead of having one ventilation for the whole house, they split it in two so the possibilities for colder bedrooms are better and easier. They also made it possible to open most of the windows.

Figure 8.The ventilation system in the house +M Ar-chitects designed. (See http://www.komforthusene.dk)

Figure 9. The natural ventilation in the passive house +M Architects designed. (See http://www.komfor-thusene.dk)

Figure 6. A building type example. (See http://www.komforthusene.dk)

Figure 7. Direct and indirect sunlight vs. the function of the chimney window vis a vis the mirror. (See http://www.komforthusene.dk)

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seperate. Figure 11, shows the windows in the kitchen area, the wall thickness becomes more visible and the charm it provides.

7. Summary and Conclusions

In this paper I have explained the fundamental aspects of a passive house, i.e. how it is differ-ent from the standard house of today, while it still has the same comfort as modern houses, and in some ways it can even offer better comfort. For an example, the ventilation system keeps the air fresh, cleans the air so thouroughly that even people with allergies can enjoy the fresh summer breeze. The main elements in a passive house are ex-plained, especially how it is different from a standard house. The four main elements are the ventilation system, the solar cells, the process in preventing thermal bridges and the triple glazed windows. Passive houses are very expensive to build be-cause of the new tecnology. Hopefully with time and as the concept spreads it will become more affordable. By following the building process of the house the +M Architects designed for the competition in Vejle it is obvious that passive houses evolve with each house that is built. The houses are made more comfortable and fit the needs of more people. This is very important in the steps of making passive houses the houses of the future. Thereby, passive houses, become closer to being the new standard for everybody.

For a graphical illustration, see Figures 8 and 9. It is completely new for passive houses to have this two way ventilaton element. The +M team also made a suggestion in their report, that a ventila-tion system of this type could in general be made more flexible without much extra effort, which would make the passive house concept more de-sirable, more favorable for everyone. (See http://www.komforthusene.dk/sw27838.asp) Figure 10 and 11 show inside the house +M Architects designed. Figure 10 shows the view from the kithcen towards the livingroom, where the stairs and the open shelves are in between, keeping the rooms open but still at the same time

Figure 11. The windows in the kitchen area in the house +M Architects designed.

Figure 10. The view from the kitchen towards the livin-groom in the house +M Architects designed.

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References

Internet reference:

Aart. Retrieved from the web january 6, 2009. http://www.aart.dk/projects/?id=59&cat=15

Advising and information site about passive houses. Retrieved from the web january 6, 2009. http://www.passivhus.dk

Information file in pdf format about the passive houses in Vejle. Retrieved from the web january 7, 2009. http://www.dtu.dk/upload/centre/lave/21-06-2007%20lavenergibygninger/komfort%20hu-sene%20-%20dtu%2021.06.2007.pdf

Isover. Retrieved from the web january 6, 2009. http://www.isover.com/SiteContent/view.do?navId=14

News and information about passive houses. Retrieved from the web january 6, 2009. Http://www.altompassivhuse.dk

Passiv haus institute. Retrieved from the web january 6, 2009. http://www.passiv.de

Phius. Retrieved from the web january 7, 2009.http://www.passivehouse.us

The comfort houses. Retrieved from the web january 8, 2009. http://www.komforthusene.dk

The passive house centre. Retrieved from the web january 10, 2009. http://www.passivhuscentrum.se

Thisted municapality. Retrieved from the web january 7, 2009. http://climate.thisted.dk/gb/2008/09/first-danish-style-passive-house/

Villa vision. Retrieved from the web january 7, 2009. http://www.villavision.dk

Book reference:

Krapmeier, Helmut; Drössler, Eckart; Cepheus, Living comfort without heating; Springer Verlag Wien New York; 2001.