The purpose of the research described herein was to establish the algorithms necessary to perform life-cycle analyses of the solar heat gain through building windows as a function of the ability of the glazing to allow the penetration and utilization within the interior built environment of available sensible radiation from the natural environment. The life-cycle cost model allows evaluations which will influence the glazing selection in response to seasonal changes in insolation and the net energy effect of orientation. The research consisted of two phases. The first included a search of the literature on energy related studies and resulted in a complication of algorithms necessary to determine heat gain through windows, equations required to determine energy cost, and equations necessary to perform life-cycle costing. The second phase of the research was a synthesis process to resolve interfacing problems between unlike calculation systems and units of measure which were encountered. This was accomplished through basic inductive processes familiar to life-cycle costing/value engineering techniques. This resulted in a schematic model to correlate the heat gain calculation with the energy cost calculation to determine the life-cycle cost for the window assembly. The research built upon existing processes to develop a more comprehensive technique for the analysis of window systems to aid in meeting economic specifications during the winter heating months. / Master of Architecture