We've been building low-energy custom
houses in western Montana (7,500
to 9,500 degree-days) for about seven
years, and have learned many lessons
about ventilation during that time.
Our typical home has an R-19 full
basement, R-28 to R-41 above-grade
walls, and R-50+ in the ceilings. We use
triple or low-e wood-frame windows,
and steel or fiberglass insulated doors.
For airtightness, we use either a continuous
poly air/vapor barrier, or the
airtight-drywall method (gaskets or
caulk and low-perm paint). Blowerdoor
tests show that our houses are
close to airtight—typically, at or below
.2 air changes per hour at 50 Pascals.
We have installed heat-recovery
ventilators (air-to-air heat exchangers)
in many of these houses. These seem to
work well when designed and