A heat pump is used for heating a house in the winter and cooling it in the summer by reversing the flow of the refrigerant. The interior temperature should be 20oC in the winter and 25oC in the summer. Heat transfer through the walls and ceilings is estimated to be 2500 kJ per hour per oC temperature difference between the inside and outside.
(a) If the winter outside temperature is 0oC, what is the minimum power required to drive the heat pump?
(b) For the same power input as in part (a), what is the maximum outside summer temperature for which the house can be maintained at 25oC?