Using the manual J load calculations, how would the AC load be affected by adding a radiant barrier under my roof deck in a 1-1/2 story home? Where can I view this calculation method? I understand over the past few years the use of a radiant barrier was included in these calculations. What are the specifics of how this impacts the calculation? I am trying to evaluate the use of a radiant barrier. Is it off setting some AC equipment cost?
This is a complex question. The best approach is to use the Radiant Barrier Fact Sheet published by the US Department of Energy. The first edition of the fact sheet was published around1990 and provides worksheet-type procedures for estimating savings. Savings depend on geographical location. The second edition of the Radiant Barrier Fact sheet contains useful information, but doesn’t provide the detailed quantitative results being requested. One way to get to the radiant barrier fact sheet is through the website maintained by the Oak Ridge National Laboratory.