Assume that you have a house with 14 windows. Each window measures 45 inches high by 32 inches wide. The windows are single-pane windows with an R = 0.9 ft^2 F h / BTU (the units given in Table 4.2 of the textbook). You are considering replacing the windows with the best commercially available windows quoted in Table 4.2 of the textbook.

a). Calculate the reduction in heat flow (BTU/hour) of energy from the house to the outside if the temperature outside is 10 F and inside is 68 F.

b). Approximately how much money in heating bills will you save over the course of 10 years under these temperature conditions if you have an oil furnace? Assume the burning of oil is 100% efficient at converting the oil energy to heat.

c). Can you find any information regarding the cost of such windows?

 

TABLE 4.2 | R VALUES OF SOME COMMON BUILDING MATERIALS Material Air layer: Adjacent to inside wall Adjacent to outside wall, no wind Cellulose, blown, 5.5-inch Concrete, 8-inch Fiberglass: Wood: 3.5-inch 5.5-inch Glass, 1/8-inch single pane Gypsum board (drywall), 1/2-inch Polystyrene foam, 1-inch Urethane foam, 1-inch Window (R values include adjacent air layer): Single-glazed wood Standard double-glazed wood Argon-filled double-glazed with low-E coating Argon-filled triple-glazed with low-E coating Best commercially available windows 1/2-inch cedar 3/4-inch oak 1/2-inch plywood 3/4-inch white pine *In English units; multiply by 0.176 to convert to Sl units, m K/W. R value (ft.F-h/Btu)* 0.68 0.17 20 1.1 12 19 0.023 0.45 5 6.6 0.9 O 2.0 2.9 5.5 11.1 0.68 0.74 0.63 0.96