HI-85-01-2 -- Thermal Transmittance of Concrete Block Walls with Core Insulation

Thermal transmittance values (U-values) of concrete block walls, with and without core insulation, tested at three laboratories are summarized . Insulations were perlite, vermiculite, expanded polystyrene (EPS) beads, and EPS inserts.

Measured U-values are compared to values calculated using the isothermal planes method. For empty core concrete block walls with known concrete thermal conductivity, measured U-values were within 10% of calculated values. However, for walls with core insulation, measured U-values differed by 0% to 40% from calculated values.

Sensitivity of wall thermal transmittance to changes in block configuration, concrete thermal conductivity, and fill thermal conductivity is discussed.

Units: Dual