Over 70 years ago, scientists invented aerogel, the least dense solid known to man, and an insulator four times more efficient than fiberglass or foam. Famously, according to Dr. Peter Tsou of NASA's Jet Propulsion Laboratory, "you could take a two- or three-bedroom house, insulate it with aerogel, and you could heat the house with a candle. But eventually the house would become too hot."
Unfortunately, aerogels remained so expensive and unwieldy that only NASA used them with any regularity. However, thanks to recent production advances, aerogel insulation is now available and affordable for consumer purchase.