[archi42]

The future is now: Modern houses around here often feature a "Ventilation system with heat recovery": You get fresh air that's heated using the air it replaces. And just let the system run 24/7. You can also recover/regulate humidity.

These systems can sometimes be retrofit into older buildings (we're doing that for our 1950s SFH), but the necessary piping is often labor intensive to install and hence prices can be insane (we were able to combine it with other measures and significantly reduced costs - I installed pipes while the roof was removed). It's much easier for new buildings of course.

[ccamrobertson]

I've heard about these systems, and they indeed sound really cool. Unfortunately living in a 50 year old home with a patchwork of poorly sized ducts, no attic and a tiny crawlspace this will never be economical for me to do.