That's a good question about where the exhaust fans expel their air.
By CODE outside, but it was common practice elsewhere to vent the to the attic.
As far as opening windows…

Thanks for the replies.
We have 2 people in the house (1.6 liters) and we run exhaust fans when showering (2 showers taken per 24hrs) or modest amounts of cooking.
We do…

We recently moved into a brand new, super energy efficient single story, 2400sqft home (Ceilings R49, Walls R23, Floors R30) and we noticed the air felt "heavy" as one visitor…