The 12th International Conference on
Passive Houses
Title: The architectural and technical
consequences of different
window details in a Danish
passive house
Camilla Brunsgaard, Ph.D. student – Aalborg University – Denmark
What is building design?
Building design are multi-dimensional –covering
both technical and architectural aspects
“As well as letting in daylight and sunlight and allowing for
natural ventilation, the window is also usually required to
provide a view while retaining privacy. As an interruption in
the external wall the window poses problems of structural
stability, heat loss and noise transmission, and is thus
arguably one of the most complex of building elements.
…Because design problems are so multi-dimensional they
are also highly interactive. Enlarging our window may well
let in more light and give a better view but this will also
result in more heat loss and may create greater problems
of privacy. It is the very interconnectedness of all these
factors which is the essence of design problems, rather
than the isolated factors themselves.” [Lawson. 1997]
The desk study
•
The goal is to investigate different placements of
windows in a Danish passive house
•
Architectural and technical consequences
– Construction, mounting and replacement
– Architectural expression
– Linear thermal transmittance
•
Case: A house from THE COMFORT HOUSES
– Some of the first certified passive houses I Denmark
– www.komforthusene.dk
– A “traditional” Danish brick house
A traditional Danish brick house
•
Construction, mounting and replacement
– Window rebate along the window opening
– where the window is mounted
– It is easy to replace the window.
•
Architectural expression and sun/ shadow
– Placed outermost in the façade gives a expression
of a plain surface.
– Windows more or less always open outwards.
– Slender frames gives light and simple expression.
More undisturbed view to the outside.
– Lets in a lot of sun.
A traditional Danish brick house
•
Linear thermal transmittance
– Demands from the building regulations is today
0,06 W/mK
– In passive houses it is recommended to have a so
called thermal bridge free constructions at
0,01W/mk
– Therefore we need to think of other solutions of
mounting the window in a passive brick house
than using a window rebate
a (mm)
Ψ
(W/mK)
10
0.157
20
0.111
40
0.067
60
0.046
80
0.036
100
0.030
120
0.027
A passive brick house
•
Construction, mounting and replacing
– No window rebate
– Displacement of the outer wall to cover the frame
From the construction site
Brick 1, U value of 0,1 W/m2K
A passive brick house
•
Architectural expression and sun/ shadow
– The placement of the window close to the façade
respects the traditional brick house solution
– The thicker frame of German passive house
windows is hided by the brickwork, gives light and
simple expression seen from outside
– Window opens inwards
which is rare in Denmark
– Little shadows on window
from wall
– Good daylight inside if
lining is light coloured
A passive brick house
•
Linear thermal transmittance
– 0,02 W/mK fulfil the building regulations
The recommendation is to use ”cold bridge free”
constructions in passive houses. A linear thermal
transmittance of less than 0,01W/mK
•
•
Is it possible to optimize the linear thermal
transmittance?
If so, what is the architectural an technical
consequences?
Variations of a passive brick house
•
Construction, mounting and replacing
– Brick 2 and 3: Mounted with special fittings,
window opens inwards, 115 and 230 mm insulated
frames
– Brick 4: Mounted like Brick 1, outward opening
window, insulated frame inside
Sketch of special fittings
Brick 1
Brick 2
Brick 3
Brick 4
Variations of a passive brick house
•
Architectural expression and sun/ shadow
– Brick 2: The shadows the wall is generating
creates a massive expression, exterior lining that
effect the daylight inside depending at the colour,
depth creates passive shading
Brick 2
Variations of a passive brick house
•
Architectural expression and sun/ shadow
– Brick 3: Same characteristics as Brick 2, but is
further away from a traditional expression, creates
association to an other typology.
Brick 3
Variations of a passive brick house
•
Architectural expression and sun/ shadow
– Brick 4: Similar to Brick 1, but the frame I more
exposed to the outside, clearer view from inside
Brick 4
Variations of a passive brick house
•
Linear thermal transmittance
– Better value the more insulation …as expected.
– But what solution is the best?
Brick 1
Brick 2
Brick 3
Brick 4
Placement
0 mm
115 mm
230 mm
0 mm
Insulated frame
No
Yes
Yes
Yes (inside)
Av. Ψ (W/mK)
0.020
0.009
0.008
0.000
Discussion
•
•
•
•
•
•
•
The lowest linear thermal transmittance might not
be the best architectural solution.
The goal of the study is not to dictate what is right
or wrong
but illustrates how important it is to think of both
architectural and technical results at the same time.
and it illustrates how influential the detail is to the
main concept of the building
-therefore important to work integrated and think
holistic!
What is the future expression of passive houses in
Denmark? Traditional design…?
…or a new architectural style?
Brick 1
Brick 2
Brick 3
Brick 4
www.komforthusene.dk
Questions?
?
…or comments