"- clothes driers: vent outside on hot days, and on warm days ... send the exhaust through an indoor heat-exchanger before venting." We live in the tropics and

"- clothes driers: vent outside on hot days, and on warm days ... send the exhaust through an indoor heat-exchanger before venting." We live in the tropics and do not have anywhere to hang clothing to dry. We use a heat-pump dryer which heats the air on the 'hot' side then through the clothes and then circulates the now-moist air through the 'cold' side which removes the excess heat and condenses the water vapour. The same air then goes through the cycle all over again. That means no huge amount of hot, wet air escaping into an already hot house which needs to be either vented or cooled. And because the energy used in heating the air is not thrown away by venting it, but is recaptured by the 'cold' side, the dryer is cheaper to run.