I have one of those tumble dryers with a condensor - it sucks air from the room with a fan, passes the air through the inside of a 'radiator' like apparatus (as to 'cool' it), and then straight into the drum chamber. from the drum chamber the (warm) air with moist passes through the external side of the radiator, and then condensation occurs.
As the air (from the room) intake is responsible for the 'cooling' of the radiator, would it be better if the room temperature will be a bit cool, as to increase the cooling effect of the radiator? As a result of the tumble dryers work, The room gets very warm, which causes the air intake temperature to increase greatly.
On the downside, cooling the outside air means the tumble dryer will have to invest more energy in warming it again.
So what would be better:
1) Leave everything as is - let the tumble dryer suck the warm air from the room, thus making it use less energy for heating up the air, but more time to work as condensation is less efficient
2) Turn on the air conditioner in the room - let the tumble dryer suck the cooler air from the room, thus making it more efficient (condensation wise), but make it use more energy to heat up the air