Elements (walls, windows, roofs, skylights, etc.) and materials (insulation, vapor barriers, siding, etc.) that enclose a building much like a sealed envelope. The building envelope is a thermal barrier between the indoor and outdoor environments and is a key factor in the “sustainability” of a building. A well-designed building envelope will minimize energy consumption for cooling and heating as well as promote the influx of natural light. These case studies and resources relate to this strategy.