Structured Assignment A heat pump is required for a single-family 2-story, 3-person, 30 ft x 30 ft x 18 ft (L x W x H), energy- efficient residential house in Philadelphia, PA, for a typical winter season. Assuming a comfortable indoor temperature is 70 F and on a cold winter day the outdoor temperature is 10 F. Exercise #1: Calculate total heat loss from a house in Philadelphia on a cold winter day. Assume 40% of the wall area is windows with U-value of 0.81 BTU/hr.ft.F. The remaining 60% of the walls has a U-value of 0.2 BTU/hr-ft?". The roof has a U value of 0.05 BTU/hr-ft-F and the floor U-value is 0.41 BTU/hr-ft-"F. For simplicity assume that the ground temperature is the same as the air temperature. (However, in your project design calculations you should refine this assumption.) Assume 0.5 air changes per hour (ACH) due to natural ventilation, such as leakage through windows, etc. Neglect any radiative heat loss/grain from the house. Exercise #2: Determine the watts of electricity needed by the heat pump for a COP of 2 on a cold winter day temperature of 10 F. Also determine the rated capacity of the heat pump assuming it has a COP of 3.5 at the rating temperature of 47"F. . Structured Assignment A heat pump is required for a single-family 2-story, 3-person, 30 ft x 30 ft x 18 ft (L x W x H), energy- efficient residential house in Philadelphia, PA, for a typical winter season. Assuming a comfortable indoor temperature is 70 F and on a cold winter day the outdoor temperature is 10 F. Exercise #1: Calculate total heat loss from a house in Philadelphia on a cold winter day. Assume 40% of the wall area is windows with U-value of 0.81 BTU/hr.ft.F. The remaining 60% of the walls has a U-value of 0.2 BTU/hr-ft?". The roof has a U value of 0.05 BTU/hr-ft-F and the floor U-value is 0.41 BTU/hr-ft-"F. For simplicity assume that the ground temperature is the same as the air temperature. (However, in your project design calculations you should refine this assumption.) Assume 0.5 air changes per hour (ACH) due to natural ventilation, such as leakage through windows, etc. Neglect any radiative heat loss/grain from the house. Exercise #2: Determine the watts of electricity needed by the heat pump for a COP of 2 on a cold winter day temperature of 10 F. Also determine the rated capacity of the heat pump assuming it has a COP of 3.5 at the rating temperature of 47"F
