The handbook on windows and energy is a general description of windows with the main focus put on the energy performance. Common window products are described by commonly used nomenclature, description of frame and sash conctructions and description of commonly used glazing types.The energy transmission through windows is described in detail including radiation, convection and conduction as well as solar transmittance of window glazing. The most used terms related to characterization of window energy performance are defined and calculation methods according to international standards are described.A method for estimation of the net energy flow on a yearly basis and/or during the heating season is presented. The method is able to combine the influence of window orientation, window size and window shape, type of glazing, frame area relative to total window area and type of spacer in sealed glazing units. Other factors as shadows and use of night insulation are described as well.Calculation methods according to international standards are explained and a short description of computer programs often used in Denmark for overall energy performance calculations, detailed calculations of heat flow and detailed calculation of light and solar transmittance is given.Different measurement techniques for characterization of window heat loss coefficient and total solar energy transmittance is described and references to interantional standards are given.Finally, the handbook includes a comprehensive list of window related standards and a list of Nordic research and development projects.Two programs are encloased in the handbook for calculation of solar radiation on inclined surfaces including a shadow correction and a simple program for evaluation of energy savings and risk of overtemperature.
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Department of Buildings and Energy, Technical University of Denmark, 1997