Heat loss through the
uninsulated basement of an
otherwise well-insulated house
can account for up to 40% of the
total house heat load. That fact
should justify spending a
reasonable amount of money on
basement insulation. But
computer simulations, controlled
experiments, and field studies
consistently suggest otherwise.
Since most basements are not
fully heated, the below-grade heat
loss is so small that, based on
energy savings alone, full wall
insulation is rarely cost effective
and sub-slab floor insulation is
never cost effective.
Figure 1 shows the calculated
annual heat loss from a basement
located in a cold climate
(Madison, Wis.). Notice the huge
difference between the fully
heated (68°F) basement and
unheated (50°F) basement cases.
This is what makes basement
insulation different from upstairs
wall and ceiling