According to the US Department of Energy, up to 45% of a home's energy loss is through
the attic, but the amount of heat actually lost will depend on where you live and how cold
your attic gets. Therefore, homes in colder climates require higher insulation values. Recommended
attic insulation levels range from R19 in the southern most parts of the US to R49 in the
northernmost. Consult your local building authority for recommended levels in your area.