A Transient Heat and Mass Transfer Model of Residential Attics Used to Simulate Radiant Barrier Retrofits, Part II: Validation and Simulations

A computer program was developed and used to implement the model described on Part I of this paper. The program used an iterative process to predict temperatures and heat fluxes using linear algebra principles. The results from the program were compared to experimental data collected during a three-year period. The model simulated different conditions such as variations in attic ventilation, variations in attic ceiling insulation, and different radiant barrier orientations for summer and winter seasons. It was observed that the model predicted with an error of less than ten percent for most cases. This paper presents model results for nonradiant barrier cases as well as cases for radiant barriers installed horizontally on top of the attic floor (HRB) and for radiant barriers stapled to the attic rafters (TRB). Savings produced by radiant barriers and sensitivity analyses are also presented. The model results supported the experimental trend that emissivity was the single most significant parameter that affected the performance of radiant barriers.