Question

Heat Loss and Heating Costs of a House Part A A house has well-insulated walls 17.1 cm thick (assume conductivity of air) and area 411 m2, a roof of wood б.бб cm thick and area 279 m2, and uncovered windows 0.626 cm thick and total area 33.4 m2. Assuming that the heat loss is only by conduction, calculate the rate at which heat must be supplied to this house to maintain its temperature at 21.4°C if the outside temperature is -11.5°C. Thermal conductivity data: air0.023 W/(m K), wood 0.12 W/(m-K) and glass-0.84 W/(m-K). Submit Answer Tries 0/6 Part B If the house is initially at 12.0°c, estimate how much heat must be supplied to raise the temperature to 21.4°C within 27.4 min. Assume that only the air needs to be heated and that its volume is 703 m3. Take the specific heat of air to be 0.24 kcal/(kg.Co) Submit Answer Tries 0/6 Part C If natural gas costs $0.080 per kilogram and its heat of combustion is 5.06x107 J/kg, how much is the monthly cost (in $) to maintain the house at a temperature of 21.4°C for 24.0 hr each day assuming 89.1 percent of the heat produced is used to heat the house? (Do not enter units) Submit Answer Tries 0/6

Answer 1