A Thermal Resistance (R-Value) Correlation for Blow-in-Blanket Mineral Fiber Insulation

Abstract

A correlation between the apparent thermal conductivity, measured at 75°F, and density of mineral fiber insulation has been developed for the fiber most commonly used in Blow-in-Blanket (BIB) applications. The correlation describes the data obtained for specimens prepared by six contractors to within ±5% in the den sity range 1.6 to 3.0 1b/ft3. R-value per inch increased from 3.85 ft2.hr.°F/Btu.in to 4.22 ft2·hr·°F/Btu·in for densities increasing from 1.6 1b/ft 3 to 3.0 lb/ft3. Thermal measurements obtained with purposely compressed test specimens were not sig nificantly different from results for uncompressed specimens at the same density. The apparent thermal conductivities for three fiberglass BIB products and one rock wool BIB product were a few percent greater than those for the corresponding loose-fill insulation. The thermal data were obtained using heat flux meters located at Ten nessee Technological University and the Oak Ridge National Laboratory.