Building envelope is a term often used in the energy and buildings industries, but it might be unfamiliar to most people. A building envelope performs similar functions to a regular old envelope you send in the mail! It encases and protects building occupants and equipment, much like a mailing envelope encases and protects a letter.
A building envelope refers to the parts of a building that act as barriers to the outside world; it includes external walls, windows, skylights, windows, and floors. When constructing a new building, building envelopes almost always have the largest impact on energy efficiency because they can help prevent the transfer of heat in or out of the building.
In the summer you want to keep your building cool and prevent heat from entering, while in the winter you want to contain heat and prevent it from escaping outdoors. A good building envelope can help with both. High-quality envelope components, like thick insulation or high-efficiency windows, help maintain indoor temperatures, while sufficient sealing of gaps and openings in the building envelope, like caulking around baseboards and windows, prevents air infiltration.
The building envelope has a very significant impact on other major energy systems within a building. Since a well-designed building envelope will lose (or, in the summer, gain) heat much more slowly than a low-quality building envelope, there is less need to run the heating, ventilation, and air-conditioning (HVAC) system. This saves money on energy costs and could even allow the HVAC system to be downsized to a smaller system, saving upfront costs. Reducing the energy use of a building also makes it easier to meet the building’s energy needs with renewable energy, such as rooftop solar, because less is needed.
By preventing drafts and uneven temperatures, a good building envelope improves the comfort of its occupants. In addition, improved envelopes can protect occupants’ health, preventing potential problems like mold, mildew, fungal growth, and dust mites. Because high-quality envelopes will also help buildings maintain their temperature during power outages, they are a powerful way to improve resilience, especially as the climate changes.