Comparison of heat transfer modeling with experimental results for residential attics

The heat transfer model was developed for fibrous insulations typically used in residential attic applications. The model predictions were compared with the experimental results obtained at the Oak Ridge National Laboratory for the three Karns Research Houses located near Knoxville, Tennessee. The model was comprised of one-dimensional coupled conduction and radiation heat transport; the unsteady energy equation and radiative transport equation were solved simultaneously. A control-volume-based finite-difference scheme was used to solve the energy equation. The radiative transport equation was solved by the method of discrete ordinates which was inherently required for solving the energy equation. Standard R-30 fiberglass insulation batts without a foil radiant barrier were studied for both summertime and wintertime conditions. The predicted heat fluxes were in good agreement with the experimental heat flux data for the entire one week period for both summer and winter. A key point of this paper is the comparison of the theoretical results with the experimental data for a week's period which has not been attempted previously. 14 refs., 7 figs., 3 tabs.