Estimating air tightness in design phase
How do I estimate air tightness (ACH 50) at the beginning of a project? This is an important input for BEOpt or other heat load calculators.
We’re designing a home for Climate Zone 7 and will be insulating everthing very tightly. Lots of foam will be used – walls (R24 OCF+R6 board), floor joists (R38 OCF) and roof (R49 SIPs on rafters). Everything will be sealed and taped. Triple pane windows with modest fenestration.
Is this likely an ACH <1, 1-2, 2+? Are there any rules of thumb for the early stage?
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