Determine the rate of net heat gain (or loss) through a 9-ft-high, 15-ft-wide, fixed 18 -in single-glass window with aluminum frames on the west wall at 3 PM solar time during a typical day in January at a location near 40o N latitude when the indoor and outdoor temperatures are 78oF and 20oF, respectively. The overall heat transfer coefficient for this window is 1.17 Btu/h·ft2·oF.