A thermal window consisting of two panes of 0.25" glass (R-value 0.08 hr. ft. F/BTU each), separated by a layer of air 0.75" thick is now used as a horizontal window in the ceiling (a skylight) of an air conditioned room. Find its R-value in the summer, when the outside is warmer than the inside, and in the winter, when the inside is warmer than the outside (in hr. ft. F/BTU). (Assume that the air is moving outside the window.) R (summer) R (winter) . xhr ft2 F/BTU xhr ft2 F/BTU