Another green term you should be aware of;
LOW-E Windows, Low emittance windows, doors, and skylights offer natural light while blocking the sun's UV rays that heat up the inside of a home, sometimes necessitating air conditioning. The special low-E glazing also stops the sun from fading fabrics, wall coverings and artwork. When shopping for low-E windows, find out what percentage of rays are blocked by checking the UV label on the glass. Most low-E products block 70% to 90%.