If you have ever been in an attic, you know how hot such spaces can get. The primary source of heat is direct sunlight. Solar heat is transmitted through the roofing material and radiated to the ceiling insulation. As the roof and insulation warm up, the attic air also becomes heated. Eventually the temperature of the entire system — roof, air, insulation, and attic floor — rises. In a non-vented system, roof temperatures can be well above 170°F, and in the attic, 140°F.