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Effective R-Value
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| The Total Effective R-Value performance of
ICFs consists of three factors: (1) the R-Value of the expanded polystyrene,
(2) the thermal mass of the concrete, and
(3) the enormous reduction in air leakage
(infiltration).
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Insulating Value
First, the R-Value of BuildBlock's polystyrene
alone is R-20, compared to wood
frame's R-9 to R-15. So ICF walls are expected
to cut the conduction losses through foundation
and above-grade walls by about half.
Air Infiltration
Air leakage accounts for as much as 40% of the
heat load requirements of a wood framed
structure. Nothing blows through solid concrete!
ICF walls reduce air infiltration by about
half, compared to wood frame.
Thermal Mass
But ICF walls do more
than cut down on the biggest types of energy
loss. The concrete gives them the heat-absorbing
property "thermal mass." This is the ability to
smooth out large swings in temperature. It keeps
the walls of the house a little warmer when the
outdoor temperature hits its coldest extreme,
and keeps the house a little cooler when the
outdoor temperature is hottest.* |
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*Energy loss graphs
and thermal mass information from
Portland Cement Association, Technology Brief 1 |
As a result, with the combined performance
of these three factors, ICF walls actually perform as high
as R-50 in some areas of the country. |
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