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<font face="Helvetica, Arial, sans-serif">Bonjour mon ami<br>
<br>
I have the PHPP 2007. It shows some drawings on Page 71, but does
not show the impact of moving the window inward or outward. It
does show a wood frame wall and the fact that this has one of the
lowest thermal flanking loss (0.01 W/mK) as shown of the four
examples. It also shows a window installation that would result in
serious rot and damage when the window leaks (windows have a high
likelihood of leaking), but I suppose that is not an energy issue
;)<br>
<br>
The Chisnall pdf shows a great example of the impact of being
really stupid, that is, putting the window in the masonry part of
the wall, and have all the insulation outboard of that. OK, this
is a big mistake, and has nothing to do with being in the center
of the wall or the center of the insulation. It is a major problem
caused by the window being installed in the uninsulated part of
the wall. Ironically, this powerpoint also seems to show this
error being committed in the photo on page 16.<br>
<br>
That one image from the passive house pdf is the close to the
answering the question, although the detail is extreme: the window
is again pushed as far out as possible, has a lot of solid wood
around it and does not actual have insulation around it (like most
windows are installed here).<br>
<br>
The passidia shows that the difference between mounting in middle
and flush to exterior is merely 0.001 W/m K. That is very very
small. Only when you install the window in the masonry (completely
missing the insulation layer) does the thermal bridge value
increase to 0.204 (obviously stupid).<br>
<br>
So again, I dont see any definitive answer that the window needs
to be installed in the middle of the wall or the middle of the
insulation (however that is defined anyway). I also have no
definitive answer (which is why I asked) but in the range of
reasonable installations, the impact seems seems to be small or
even non-existent (by small I mean <0.03 or so W/mK). Of
course, the window needs to be installed with the insulation
layer, and it should ideally be surrounded by some insulation in
the rough opening. Many of the PH drawings are unbuildable, as
they show no rough opening (I have worked in Europe and I know
that the window rough openings are sized larger than the window to
allow for installation, just like they are in north America).<br>
<br>
</font>
<pre class="moz-signature" cols="0">Dr John Straube, P.Eng.
<a class="moz-txt-link-abbreviated" href="http://www.BuildingScience.com">www.BuildingScience.com</a></pre>
<br>
On 12-01-29 12:19 PM, John Daglish wrote:
<blockquote cite="mid:92732805.20120129181909@free.fr" type="cite">
<pre wrap="">Bonjour John,
Sorry not to get back sooner, have been busy.
They calculate the installed value of the thermal bridge heat loss
coefficient W/m.K.
If you look at page 71 of the PPHPP assive House Planning Package 2007 booklet it
shows some best practices for exterieur insulation, concrete form
block, timber I beam, timber frame.
<a class="moz-txt-link-freetext" href="http://www.can.uk.net/conference_2011/leicester/downloads/peter_chisnall.pdf">http://www.can.uk.net/conference_2011/leicester/downloads/peter_chisnall.pdf</a>
p27 cavity wall insulation 0.11 0.01 or 0.12 W/m.K ext mid int
p28-29 external wall insulation 0.08 or 1.84 W/m.K "mid" int
<a class="moz-txt-link-freetext" href="http://gse.cat.org.uk/downloads/passive_house.pdf">http://gse.cat.org.uk/downloads/passive_house.pdf</a>
p9-10
There is a more complete explanation on the web site <a class="moz-txt-link-freetext" href="http://passipedia.passiv.de/passipedia_en/start">http://passipedia.passiv.de/passipedia_en/start</a>
but it is behind a "pay" wall ie. you have to become a member.
but not in German it seems :
<a class="moz-txt-link-freetext" href="http://passipedia.passiv.de/passipedia_de/planung/waermeschutz/fenster/fenstereinbau">http://passipedia.passiv.de/passipedia_de/planung/waermeschutz/fenster/fenstereinbau</a>
external wall insulation ETICS
0.18 or 0.017 or 1.22 W/m.K ext mid int
0.86 or 0.84 or 1.22 W/m2.K window installed U value
PS angle bracket fixings to place the window in an ETICS wall should
have thermal insulating shims!! Even the cavity wall brick fixings
fabricants are doing this now.
Cordialement
</pre>
</blockquote>
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