[Greenbuilding] passive haus article

[Topher]

On 8/21/2013 6:38 AM, Alan Abrams wrote:
> re the GB advisor article:
> 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, ...

I think that this is a bad way to think of it.  A bit like complaining 
when someone buys a big mac and a /diet/ 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.

The choices are (imho) to optimize /each/ 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/lots/ 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.

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.

Note that NOT optimizing is not an option.

> the downside is that there seems to be no reasonable substitute for foam.

Foam glass seems to be a good option for under slabs.  We just need to 
get a supplier here in the US.

Thank You Kindly,

Corwyn / Topher Belknap

-- 
Topher Belknap
Green Fret Consulting
Kermit didn't know the half of it...
http://www.GreenFret.com/
topher at greenfret.com

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