March/April 2009
A version of this article appears in the March/April 2009 issue of Home Energy Magazine.
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March 09, 2009
How Tight Is a Passive House? I love your magazine and Web site. You inform me about cutting edge technology for advising, building, and renovating—backed up by tests and studies—it isn’t guessing. That is why I was troubled by your recent sidebar on a Passive House (“First U.S. Retrofit to Passive House Standards,” Nov/Dec ’08, p. 25). Your standards for an airtight house are minimal at 0.6 ACH. For EarthCraft and Energy Star standards we are looking for 0.6 ACH (natural) in a renovation. We are looking for 0.35 ACH in a new house. An ACH of 0.6 in a house is not tight by Energy Star standards or by me for new housing. I do have an engineering degree, but I am recognized for my common sense in building applications to obtain cost-effective energy efficiency. I say this because I don’t want you to think I am just finding fault with numbers. Keep up the good work. Bob Congdon Hampton Roads, Virginia Author and architect Nabih Tahan replies: I think that you are confusing natural airtightness—ACH (nat)—with airtightness under pressure. The Passive House requirement is 0.6 air changes per ...

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