On the performance of radiant barriers in combination with different attic insulation levels

Experiments and computer simulations were conducted to evaluate the performance of radiant barriers under three different insulation levels in residential applications. The experiments were conducted in central Texas, USA using side-by-side comparisons in which two houses, with identical floor plans and thermal profiles, were used. The houses were instrumented, calibrated, and their heat transfer rates across the ceilings were measured and recorded. A heat and mass transfer model was used to run the computer simulations. The results suggest that the reductions in heat transfer (on a percentage basis) produced by the radiant barriers decrease as the attic insulation resistance increases. On average, the experimental summer heat flow reductions produced by the radiant barriers in combination with attic insulation resistance levels of 1.94, 3.35, and 5.28 m(2) K/W (R = 11, 19, and 30) were 42, 34, and 25%, respectively. The simulations, driven by typical meteorological year (TMY) data, produced yearly heat flow reductions of approximately 44, 28, and 23% for the same insulation levels, respectively. (C) 2000 Elsevier Science S.A. All rights reserved.