Low-E: A word you see often in the window industry, so here is what it means: Low-E is the standard term in the window and glass industry that refers to the energy efficiency capabilities of the product. Low-E stands for low emissivity or low emittance. Often used in double and triple glazing units, the low-E coating on glass controls the transfer of radiant heat with insulated glazing thereby reducing energy loss by 30 percent and upwards. A low-E coating is a virtually invisible layer of metallic oxide that is deposited (generally at the time of manufacturing) on the surface of one or more panes of glass. The low-E serves to reduce the transfer of infrared heat and lowers the U-factor of the window, making the window an effective fighter against heat loss. The U-factor is the rate by which the window (or door, or skylight) conducts a non-solar flow of heat: the lower the value of the U-factor, the greater the energy efficiency of the product. The official U-factor ratings are validated by the National Fenestration Rating Council (NFRC) that tests and rates the complete window performance, that is, the frame and spacer material. Windows can gain and lose heat through a number of sources: through the conduction of heat from the glazing or frame; through heat from the sun that radiates into and out of the house from such elements as furniture, upholstery or people and other objects in a room; and air leakage through and from the windows. There are a number of benefits of low-E glass: light can enter the room while providing thermal insulation; the costs to run heating and air conditioning systems is drastically reduced; homeowners can maintain a comfortable living environment without adjusting the thermostat settings; and the possibilities of condensation are greatly decreased. For more information on low-E and other window and door facts, contact Reg or Tom at 703-256-0600, or visit us here at www.WindowsPls.com. Thank you for your business and keep your questions coming our way.