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<div class="moz-cite-prefix">On 8/21/2013 6:38 AM, Alan Abrams
wrote:<br>
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cite="mid:CADj3_s6_QVNh5VTaXH76ZGUk6Ki62boE-=6BFRAnF3aqh2yr3w@mail.gmail.com"
type="cite">
<div dir="ltr">re the GB advisor article:
<div>Conversely (assuming you are looking at net heat loss
through the building envelope), increasing, say wall
insulation, to compensate for heat loss under a slab, ...</div>
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<br>
I think that this is a bad way to think of it. A bit like
complaining when someone buys a big mac and a <i>diet</i> coke.
Heat losses (exactly like food calories) are additive. There is no
way to 'compensate' for a heat loss by making some other part
better.<br>
<br>
The choices are (imho) to optimize <i>each</i> surface both in
terms of money and energy, or optimize the entire building including
heating, cooling, and ventilation systems. The trouble with the
former is that you can end up producing the highest cost building
(even if cheap to heat). Passivhaus attempts to circumvent this by
replacing expensive mechanical systems with<i> lots</i> of cheap
insulation. This approach has the advantage of moving costs from
volitilely priced energy to constant priced interest on up-front
insulation. If fuel prices double (again) the Passivhaus (or
equivalent) is most likely to survive. <br>
<br>
I hear complaints that Passivhaus is hide-bound with respect to
their metrics (and they are, a bit), but the solution is to make
better (or more locally optimized) metrics, with just as much
evidence behind them.<br>
<br>
Note that NOT optimizing is not an option.<br>
<br>
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cite="mid:CADj3_s6_QVNh5VTaXH76ZGUk6Ki62boE-=6BFRAnF3aqh2yr3w@mail.gmail.com"
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<div>the downside is that there seems to be no reasonable
substitute for foam. <br>
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<br>
Foam glass seems to be a good option for under slabs. We just need
to get a supplier here in the US.<br>
<br>
Thank You Kindly,<br>
<br>
Corwyn / Topher Belknap<br>
<pre class="moz-signature" cols="72">--
Topher Belknap
Green Fret Consulting
Kermit didn't know the half of it...
<a class="moz-txt-link-freetext" href="http://www.GreenFret.com/">http://www.GreenFret.com/</a>
<a class="moz-txt-link-abbreviated" href="mailto:topher@greenfret.com">topher@greenfret.com</a>
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