Cool air is passive, but heat is always on the move in your home. Installation of a radiant barrier can slow it down. Heat rises, transfers through ceilings and walls, or radiates from a hot surface to a cooler one. Plugging air leaks can prevent heat loss from living spaces due to convection in winter. Adding insulation reduces downward conduction from a hot attic in summer. But heat from the sun’s energy radiating through the roof and into the attic can only be reduced by radiant barrier material.