[Greenbuilding] Aggressively Passive: Building Homes to the Passive House Standard
Corwyn
corwyn at midcoast.com
Mon Jan 10 07:31:36 CST 2011
On 1/9/2011 4:40 PM, Gennaro Brooks-Church wrote:
>if you build for long enough in a
> certain area you know how thick the insulation should be.
This struck me. How do you know? For that matter, what is your measure
whether the insulation is 'thick enough'.
It is easy enough to make any moderately insulated structure warm
enough. All you need to do is pump more energy into it. So homwowners
not complaining about how cold it is, is not a good measure.
Furthermore, homeowners only comparison for how much fuel they 'should'
be using, is their neighbors. Sadly, even moderately efficient house
are going to look good compared to the rest of the buildings out there.
Most builders around me have no idea what 'thick enough' is.
The only way I can think of, to evaluate 'thick enough' is to compare
the cost of fuel to heat the building over some projected lifetime,
against the cost of various insulation levels (and use some dreaded
spreadsheet :-). Of course, these numbers depend on the price of fuel,
the mortgage interest rate, the price of insulation, anticipated fuel
inflation. and so on. It also means that the number changes every time
one of those things changes. If one is putting in insulation levels
determined in the 80's one had better be paying 80's prices for fuel.
I would love to have a better metric. Can you share yours?
Thank You Kindly,
Corwyn
--
Topher Belknap
Green Fret Consulting
Kermit didn't know the half of it...
http://www.greenfret.com/
topher at greenfret.com
(207) 882-7652
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