Question

On an average winter day (3 or 38 ) in a typical house, energy already in the house is lost at the following rates: (i) 2.1 is lost through partially insulated walls and the roof by conduction; (ii) 0.3 is lost through the floor by conduction; and (iii) 1.9 is lost by conduction through the windows. Additional heating is also needed at the following rates: (iv) 2.3 to heat the air infiltrating the house through cracks, flues, and other openings and (v) 1.1 to humidify the incoming air (because warm air must contain more water vapor than cold air for people to be comfortable). On the same day in the same house some thermal energy is supplied by heating in the following amounts: (i) sunlight through windows, 0.5 ; (ii) thermal energy given off by the inhabitants, 0.2 ; and (iii) thermal energy from appliances, 1.2 .

Part A Suppose that the following design changes are made to the house described above: (i) additional insulation of walls, roof, and floors, cutting thermal losses by 60 ; (ii) tightly fitting double- glazed windows with selective coatings to reduce the passage of infrared light, cutting conduction losses by 70 ; and (iii) elimination of cracks, closing of flues, and so on, cutting infiltration losses by 70 . What is the total rate at which energy is lost from this house? Express your answer to two significant figures and include the appropriate units. ANSWER: = -2.6 Please show how to get to answer per professor answer is -2.6 kW

Answer 1