Daylighting - Let the Sun Shine In Isn't it nice that being "green" (environmentally responsible) can put green in your pocket? "Daylighting" is a simple concept. More windows = more light. And make the windows operable (able to open) can even save on AC. Big savings in lighting are obvious, and in cooling pretty obvious (in borderline weather, folks can open a window and save on AC). Also savings in heating in temperate weather — more light provides natural heat. (Make the windows low-e and reflective and you won't lose heat in cold weather.) Daylighting can provide even greater energy savings when coupled with light fixtures that sense the amount of natural light in a space. If enough natural light is present, the lighting dims or shuts off completely.