Thermal Transmittance of Concrete Block Walls with Core Insulation

Abstract

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 conduc tivity, 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, con crete thermal conductivity, and fill thermal conductivity is discussed.