In Search of Simple, Low-Cost Ventilation

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