This document summarizes a student paper about passive houses. It defines a passive house as one that uses very low energy through features like excellent insulation, an efficient ventilation system, and triple-glazed windows. It provides details on the key elements of passive houses and explains why they are more expensive to build initially due to new technologies. The document concludes by summarizing a specific example of a passive house built in Denmark, highlighting how its design improved comfort and flexibility over traditional passive house standards.

1. Arkitektskolen Aarhus
January 2009
Class 2AD
Teacher: Helle Christensen
Student: Árný Árnadóttir
The Passive House
- house of the future -

2. 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

3. 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)
3

4. 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,
4

5. 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)
5

6. 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)
6

7. 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)
7

8. 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.
8

9. 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.