Analysis of Attic Radiant Barrier Systems Using Mathematical Models

Abstract

During the past six years, the Florida Solar Energy Center (FSEC) has conducted extensive experimental research on radiant barrier systems (RBS). This paper presents recent research on the development of mathematical attic models. Two levels of modeling capability have been developed. A very simplified model based on ASHRAE procedures in used to study the sensitivity of RBS performance parameters, and a very detailed finite element model is used to study highly complex phenomena, including moisture adsorption and desorption in attics. The speed of the simple model allows a large range of attic parameters to be studies quickly, and the finite element model provides a detailed understanding of combined heat and moisture transport in attics. This paper concentrates on a parametric analysis of attic RBS using the simplified model. The development of the model is described, and results of the parametric analyses are presented and discussed. Preliminary results from the finite element model are also compared with measurements from a test attic to illustrate the effects of moisture adsorption and desorption in common attics.