The improvements in efficiency technologies for windows also apply to skylights, but have a greater effect since they receive direct sunlight in the summer and greater outside/inside temperature differentials in the winter (Energy Star
). A skylight's efficiency is dependent on three components: glazing, operation and use, and shape (Energy Savers
standards for skylights, as with windows and doors, are based on climate. Energy Star standards for Southern California, in the South-Central climate, has weaker U-Factor standards, because there is less of a concern regarding heat loss through the skylight during the winter in an area that does more cooling than heating, and stronger SGHC standards, because you want to limit how much heat comes from direct sunlight through the skylight during the summer in a warmer climate. For both U-Factor and SGHC standards, the lower the number, the higher the insulating quality, and the less heat gets out (winter) or comes in (summer).