On the performance of radiant barriers in combination with different atticinsulation levels

Experiments and computer simulations were conducted to evaluate the perform ance of radiant barriers under three different insulation levels in residen tial applications. The experiments were conducted in central Texas, USA usi ng 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 record ed. 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 r esistance increases. On average, the experimental summer heat flow reductio ns produced by the radiant barriers in combination with attic insulation re sistance 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 meteorolo gical year (TMY) data, produced yearly heat flow reductions of approximatel y 44, 28, and 23% for the same insulation levels, respectively. (C) 2000 El sevier Science S.A. All rights reserved.