The energy efficiency of ICF homes begins with the
EPS (expanded polystyrene) blocks used to form the shell, or exterior wall of a
home. These foam blocks have a natural R-value of R-16 to R-30. The "R" in
R-values is often used to determine how energy efficient something is, whether
it is insulation, windows, or any other construction material. Typical 2x4
built homes are insulated from R-11 to R-19. When combined with the thermal
mass properties of the concrete, an ICF wall has performance R-values
comparable to a 2x6 wall insulated to R-50.