A window in my home office has heavy curtains in front of it as an additional layer of insulation. During the day the curtains are pulled aside to allow the light to enter the room and exposing the glass window. The room is heated and kept at 20 deg C. How much heat (J) leaves the room through the 70 cm 90 cm glass window pane that is 4 mm thick when the outside winter temperature is -5 degree C, in 4 hrs? ( 1m = 100 cm) (1m = 1000mm)