Gary R. Lloyd wrote:

What are the pros and cons of tighter construction with forced
ventilation versus passive ventilation (leakage), assuming they both
result in roughly the same amount of ventilation?

Here's my opinion:

Advantages Disadvantages

A) Natural leakage Lower first cost Higher fuel consumption
More reliable in winter and summer
Possibly better IAQ: Can't use HRV
CO, CO2, H20 often Lower RH in winter
diluted with a Wet insulation and drywall
large flow of Possible wood rot, mold,
fresh air and mildew inside walls
No ventilation at all
on still mild days

B) Positive ventilation More uniform fresh air
and temp distribution
around the house
It's always easier to
bring air in than to
keep it out, turning
B) into A) if needed...

Nick (who just got a call from two Lennox lawyers saying they may change
the energy-savings claim on their humidifier web site "if it turns
out to be inaccurate in the opinion of our engineers" :-)