Express your answer in kWh/d.

Question

How much power is required to cool a house to 22oC on a 40oC day if the "leakiness" (heat-loss coefficient) of the house is 3.6 kWh/d/oC? You may assume that the air-conditioner cooling the house is 100% efficient.

Express your answer in kWh/d.

Answer 1

Hi Sean, 

 

  The rate of power usage (kWh/d) depends on the product of heat-loss coefficient coefficient and the temperature difference to be maintained.

 

      dP/dt = 3.6 kWh/d/°C × (40°C - 22°C) = 64.8 kWh/d  

 

  If the question means that the house is cooled from 40° to 22°C, then with everything being linear for that period of time , dP/dt = 32.4 kWh/d since  the "average" temperature  difference would be 9°C