High-Performance Buildings : : Definitions : : High-Performance Envelope

High performance envelope: Roofs, ceilings, exterior walls, windows, doors, external floors and soffits are components of the building envelope. A high performance envelope means that each component is designed to minimize the transfer of thermal energy which in turn creates an energy efficient or "tight" building. Dartmouth's high performance envelope includes:

• Triple-glazed, argon-filled windows. Three layers of translucent or transparent element of a window assembly that lowers the amount of energy loss by inhibiting the transmission of radiant heat while still allowing sufficient light to pass into the space.
• Double-glazed, argon-filled doors. Two layers of transparent glass that inhibits the transmission of radiant heat while still allowing the door to open and close, and provides sufficient light to pass into the space.
• Spray foam insulation. Zero-ozone-depleting insulation that is non-toxic and is made of polyurethane foam ­ the same kind of insulation appliance manufacturers have used in refrigerators and water heaters for years. The liquid polyurethane is pumped through pressurized spray nozzles. As it lands on the surface of the structure's walls and ceilings, it expands to about 100 times its original volume forming a continuous insulating barrier. Over time, as the structure expands and contracts, so will the foam insulation. This eliminates cracks and spaces for warm air to escape.