Evaluation of Ceiling Heat Fluxes in Residential Buildings with Attic Radiant Barriers in Prevalent Climates across the United States

This paper illustrates how climate affects the performance of attic radiant barriers. The 48 contiguous United States were subdivided into nine predominant climatic regions and a transient heat and mass transfer computer model was used to evaluate the performance of radiant barriers, based on ceiling heat transfer reductions. The simulations were driven by TMY2 weather data from stations within the climatic regions. Results based on integrated hourly ceiling heat fluxes over a 3-month period showed that radiant barriers were most effective in the Tropical Savanna climate (i.e., southern tip of the State of Florida) and least effective in the Mediterranean climate (i.e., the State of California and western regions of the States of Nevada and Arizona). Summer-integrated percent reduction in ceiling heat transfer, based on an insulation level of 3.5 m²K/W (R-19), ranged from 36.8 percent to 2.3 percent. Peak-hour percent reductions in ceiling heat flux ranged from almost 100 percent in the Marine West Coast climate (i.e., the states of Oregon, Washington, the western region of Idaho, and the northwest part of Nevada) to 23 percent in the Desert climate (i.e., large portions of the states of Arizona, Nevada, Utah, New Mexico, and western Texas).