This Home Energy Brief focuses on the building envelope. It provides guidance for making improvements to a residential building envelope. One of the key features of an energy efficient home is a tight and properly insulated building envelope. Improvements such as adding insulation, sealing air leaks, and improving window features provide simple and affordable measures that often do not require a professional contractor. A typical homeowner may invest $1,000 on his home’s building envelope, but he can save up to $300 on energy bills each year and enjoy year round indoor comfort. As of 2012, the Home Energy Briefs have been updated and adapted to Southern California Edison’s Online Home Energy Guide.