These calculations were performed using the following assumptions:
1. Calculation method below, is the series parallel (also called isothermal planes) method recommended for masonry concrete in
the 1993 Fundamentals Handbook and described in the Series-Parallel Procedure for Calculating the Overall Coefficient of Heat
Transfer.
2. Unit dimensions are taken from Calculations of U-values of Hollow Concrete Masonry by Ralph C. Valore. Faceshell and web
thicknesses are the same for sixteen and eighteen inch long units.
3. Thermal resistivity of concrete is based on an oven dry condition.
4. Insulation is expanded polystyrene with a thermal resistivity of 3.85 hrft2.0F/Btu.
5. R-value includes indoor and outdoor air surface resistances of .068 and 0.17 hrft2.0F/Btu respectively.
6. Calculations includes 3/8” mortar joints. Thermal resistivity of mortar is 0.2 hrft2.0F/Btu in..
Concrete Applications
