AT-01-10-4 -- A Simplified Analysis of Radiant Heat Loss Through Projecting Fenestration Products PDF

Current window analysis algorithms can deal with many features, including low-e coatings and substitute fill gases. These methods were developed for products with planar glazings. Results can be generated for projecting products such as greenhouse windows, but the indoor-side heat transfer coefficient must be reduced to reflect differences in convection and radiant exchange for this geometry. Two simplified models are developed for radiant heat loss to projecting windows and are shown to agree well with a pseudo three-dimensional multi-element computer-based calculation. It is confirmed that the indoor-side heat transfer coefficient does not need to be accurately known to characterize a well-insulated window. More research is needed to quantify indoor-side convective heat loss before radiant exchange models can be verified and projecting products can be well characterized in general.

Units: SI