A QUASI-STEADY-STATE MODEL OF ATTIC HEAT-TRANSFER WITH RADIANT BARRIERS

During the cooling season, heat transfer from the attic into the condi tioned space of a residence can represent a significant portion of the total envelope heat transfer. Radiant barriers are one method used to reduce this heat transfer. A quasi-steady-state model was developed f or predicting attic heat transfer in residences with radiant barrier s ystems. The model was used to estimate the reduction in cooling load t hat would occur with a radiant barrier and to identify important const ruction and environmental parameters that influence this cooling load reduction. The model's output consisted of hourly ceiling heat fluxes inside the house based on hourly weather data inputs. Model results we re compared with detailed experimental results from two small test hou ses. The model predicted typical summer heat flux reductions of betwee n 35 and 43% with different radiant barrier configurations and levels of insulation. These compared to measured heat flux reductions of betw een 29 and 37% in attics under the same conditions. Sensitivity studie s were also conducted to show the effect of uncertainty in several of the important physical attic parameters on the final heat flow predict ions of the model.