[Greenbuilding] Aggressively Passive: Building Homes to the Passive House Standard

[Corwyn]

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...
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