Over the past few years, I've been
surprised at the number of fairly airtight
new houses I've seen. I'm not
talking about houses built only by
energy specialists either. Many of the
builders are just trying to produce the
best house they can, and have learned
enough to close off the big leaks in
the ceilings. They know about
recessed lights, plumbing chases, and
kitchen soffits, and they use sheetmetal
firestops around chimneys
where they pass through ceilings.
The houses I've pressure-tested that
were built since 1984 typically range
from 3 to 5 air changes per hour (ach)
at 50 Pascals (compared to 1 to 3 ach
for very energy-efficient houses, and 9
to 18 for typical houses