THE CURRENT
BUILDING ENVELOPE
There has been a focus in the news on green insulation and the building envelope. Here's the word from the experts, partners Stuart Disston, AIA, and McKee Patterson, AIA
What does whole house envelope mean in the 2010 house?
Stuart - The whole house building envelope simply means insulating the entire perimeter: attic, rafter, basement and crawl space. Insulating all these spaces puts all the plumbing lines and mechanical equipment in a conditioned space which makes them more efficient.
Traditional Insulation (at left)
Modern Insulation (at right)
Is there a downside to building such a tight structure?
Mac - The assets greatly outweigh the liabilities. Not only are temperatures easily controlled and more efficient, but a tight envelope, high grade double paned windows and doors and high performance insulation, etc., masks outside noise. You do need to install equipment to change the air, mixing outside with inside air.
What types of insulation do you feel are both effective and green?
Stuart - Products with the highest R value (thermal resistance) are the most efficient. Though the most expensive, closed-cell foam has the highest R value, stopping air and moisture. Pictured below is closed-cell foam we've used in an attic eave where its density adds strength to the ceiling.
Closed-cell foam insulation in attic.
What about open-celled and cellulose?
Mac - Open-cell foam insulation costs less than closed-cell and has a lower R-value but is more appropriate for spaces that need to be accessible. Manufacturers have also "greened" foam products by replacing petroleum based chemicals with resin from soy or castor oils.
Lycene, Open-celled foam insulation, a "greened" product.
Stuart - Cellulose is certainly the greenest of all insulation, as it is made from newspaper or wool, treated to be fire retardant. Tightly packed cellulose is a superb air-blocker, as it can be installed in areas that fiberglass cannot reach.
Nu-Wool cellulose insulation.
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