The space between the panes of a double-glazed window can be filled with either air or carbon dioxide at atmos- pheric pressure. The window is 1.5 m high and the spac- ing between the panes can be varied. Develop an analysis to predict the convection heat transfer rate across the window as a function of pane spacing and determine, under otherwise identical conditions, whether air or car- bon dioxide will yield the smaller rate. Illustrate the results of your analysis for two surface-temperature conditions: winter (-10°C, 20°C) and summer (35°C, 25°C).