Overall building performance is tied very closely to the condition of the building envelope, yet it is very often overlooked when diagnosing building performance problems. The building envelope can be defined as the physical divider between the interior and the exterior environments of a building. The envelope functions as the outer shell, and working with the mechanical conditioning systems, helps maintain the indoor environment and facilitate its climate control. Building envelope design is a specialized area of architectural and engineering practice. Designing a building envelope draws from all areas of building science and indoor climate control.
The building envelope serves many functions and can be separated into three categories: Support, Control and Finish. The foundation, walls, doors, roof and windows are the physical components of the building envelope. The effectiveness of a building envelope can be determined by some common measures, including comfort (the physical protection from the weather and climate), hygiene and public health (measured by indoor air quality), durability and energy efficiency.
If the envelope does not work properly, there are many issues that can arise. Water leaks, excessive filtration, snow/ice formation on windows as well as visual and physical damage to the building are just some of the issues. There are also many benefits gained from a properly functioning building envelope. By eliminating uncontrolled leakage and drafts, building occupants will enjoy improved comfort. Properly working building envelopes also help save wasted energy as well as improve moisture control. The biggest benefit is in the cost savings; it has been shown that companies who ‘tighten’ their building envelope, can save up to 36% in energy costs.