Wright, John L.Sullivan, Harry F.2017-03-222017-03-221995-08CH-95-8-3http://hdl.handle.net/10012/11576© 1995. American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc. (www.ashrae.org). Published in ASHRAE Transactions, Vol. 101, Part 1. For personal use only. Additional reproduction, distribution, or transmission in either print or digital form is not permitted without ASHRAE’s prior written permission.A simple two-dimensional (2-D) numerical control volume formulation is presented that can be used to model heat transfer through a vertical insulated glazing unit. This model accounts for natural convection of the fill gas (including the effect of secondary cells), conduction within the solid materials, and radiant exchange between the various surfaces facing the fill-gas cavity. This model closely reproduces average and local heat transfer rates measured using a guarded heater plate apparatus. Simulations clearly show that fill-gas motion causes the minimum indoor surface temperature (during cold weather) to be located at the bottom edge of the indoor glazing. Calculated results were also used to gain insights into heat transfer patterns in glazing systems with various combinations of low-emissivity coatings, fill gases, and edge-seal designs.enEnergy conservationEnergy consumptionWindowsMathematical modelsHeat transferCommercial buildingsResidential buildingsEnergy utilizationArticle