Substrate Barrier Effects on Total Heat Transfer for a R-30 Fibrous Insulation Batt

Abstract

By implementing various substrate barriers to a R-30 fiberglass in sulation batt, this research shows the overall changes in the substrate heat flux. Inde pendently, a plastic vapor barrier, and both a perforated and nonperforated radiant barrier are analyzed in this study. Conduction, radiation heat transfer, and moisture (mass) transport are considered to be the main contributors to heat transport within attic fiberglass insulation. A transient, one-dimensional, computational thermal model has been developed to simultaneously model all three of these heat transport mechanisms, which allows the total heat flux at the attic insulation substrate to be predicted. This numerical model has the capabilities to determine the effect on each of the three modes of heat transfer once a substrate barrier has been added. Summer time experimental data were collected at an occupied North Mississippi residence for cases with and without a vapor barrier at the substrate for R-30 fiberglass insulation. Within this investigation, experimental and predicted total heat transfer results are compared and analyzed. Profiles such as temperature-time histories, vapor H₂O con centrations, and individual modes of heat transfer plots are presented to support the experimentally determined overall effects on the heat transfer at the substrate once a substrate barrier has been implemented.

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