James Wilkinson Sword wrote: "No, you just need to have no more than one hole. Two holes (on different sides of the building) means a through passage of air. "

You just love to refute everything I
say, don't you? Fact of the matter
is, heat's propensity is to RISE.

25 years ago, we replaced all the
windows with thermopanes, and
blew insulation into the exterior
walls. Guess what: the house
felt COLDER in winter than before
we did all that. Why? because we
neglected to consider the ATTIC
FLOOR. It's called the stack effect.
Drafts under first floor doors
INCREASED.

So we beefed up the attic insulation,
and weather stripped the edges
of the attic hatch. Drastically reduced
the stack affect, and upstairs bed
rooms stayed much warmer in winter,
even over night with the thermostat
setback program.