A heat pump must be used to heat a house in winter and, in reversing its operation, to cool it in summer. The indoor temperature should be maintained at 20C. The heat exchange through the walls and the roof is rated at 2400 kJ/h per degree temperature difference between inside and outside. a) If the outdoor temperature in winter is 0C, what is the minimum power required to operate the heat pump? b) If the power supplied is the same as in (a), what is the outside temperature permissible maximum to maintain the interior temperature at 20C?

Rp.: a) 0,91 kW b) 40C