What Is A Deep Energy Retrofit?

In a deep energy retrofit, sealing the holes is important, but so is upgrading materials that are fundamental for the energy efficiency of an older home, using materials that make it more on par with newer ones. For example, as part of a deep energy retrofit, you might replace all your windows with triple pane insulated glass unit windows, and insulate the underside of your roof to help prevent heat penetration into your attic.