Attic fans and radiant heat subfloors are two smart ways to regulate a home's atmosphere. A hot attic acts like a radiator, pushing heat into your living spaces and sending temperatures soaring. In colder climes, attic heat build-up causes snow to melt and run down to where it freezes at the eaves, leading to destructive ice damming.
Not only can a passive, solar-powered attic fan combat these problems, but it's the most environmentally-sound ventilation available. As for radiant heating, the idea's been around for 2,000 years and is just now being perfected. Find out more here.