To measure the length and width of a home, follow the illustrations below. This calculates the exterior walls for the “insulate walls” recommendation as well as the foundation perimeter that is used in the basement and crawlspace calculations. The wall square footage that's calculated from this is also used when calculating the window square footage as a percentage of wall area.

The grey portion of the illustration is the footprint of the actual house's conditioned space, then imagine a rectangle drawn around the house.

Note: DO NOT INCLUDE unconditioned garages, carports, porches, or any other unconditioned space as part of the house shape. If unconditioned space falls within the rectangle surrounding the conditioned space, then do nothing different.

If the house is a U shape, then you have additional exterior walls that need to be accounted for that the imaginary rectangle does not cover. In this instance, add the length of “X” to the Width of the house.

While in the app, hover over the title of the field (House Length or House Width) to see the tooltip.

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