The Thermal Boundary

When you first think about conserving energy and making the place you live more comfortable, it may be best to start by identifying your home's thermal boundary.

The thermal boundary, sometimes referred to as the thermal envelope, which restricts or slows the flow of heat, is a catch-all term for the parts of the home that separate the indoor areas that are heated and cooled (conditioned space) from the outdoors or any areas in your residence that are not heated or cooled (unconditioned space). Conditioned spaces are the living room, bedrooms, bathrooms, kitchen, etc. Besides the great outdoors, other unconditioned spaces are usually the attic, crawl spaces, unfinished basement and the garage.

Defining the thermal boundary seems easy at first, but when you begin to look at the many points where the boundary may be breached, it can become a challenge. Add to this that a home's air barrier—which is made up of any material that restricts air flow, such as sheathing, house wrap, and drywall—should be in alignment with the thermal barrier. Remember, most insulation such as fiberglass does not stop air movement. Without an aligned air barrier, fiberglass insulation provides little thermal benefit. An ideally insulated home will have fully aligned thermal and air barriers that are contiguous and continuous over the entire building—encapsulating the conditioned space, thus creating a good thermal envelope around your living area.

How is your Thermal Boundary Performing?

Have it Tested,