[Greenbuilding] Exterior insulation retrofit

nick pine nick at early.com
Sat May 7 13:10:52 PDT 2011

bill.allen at verizon.net wrote:

>>>... I am thinking Marvin Ultimate clad (wood with aluminum cladding on 
>>>the outside) but they cost an arm and a leg, even more so with triple 
>>>glazing to reach R5. Alternatives?

>>Passive solar air heaters, eg 

>I guess you are suggesting I turn my house into a barn.

Not at all. Air heaters can go right over existing house walls, with more 
insulation behind them, s'il te plait.

>That's low on the spouse acceptance factor...

The SAF would probably be higher if the plastic film damper opened into the 
bottom of the air heater, vs into the house from the top.

The materials for Gary's air heaters cost about $2/ft^2 and 1 ft^2 collects 
the heat equivalent of about 1 gallon of oil per year. You might double that 
with hired labor.

Will $1K of these windows save 250 gallons of oil per year? :-) If not, 
leaving the original windows in place and adding air heaters could be more 


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