De-humidifiers dry the air without cooling it. They work like a normal air conditioner, except that a heat exchanger is placed between the intake and exhaust. In combination with convection fans they achieve a similar level of comfort as an air cooler in humid areas, but only consume about a third of the electricity. They are also preferred by those who find the draft created by air coolers discomforting. Air conditioners automatically act as dehumidifiers when they chill the air and thus need to handle the accumulated water as well. Some models use the condensing coil and fan to evaporate the accumulated water into the outdoor air, while normal units simply allow the water to collect in a tank. Some air conditioning units need to be connected to a drain.

A dehumidifier is an appliance that reduces the level of humidity in air, usually for health reasons, as humid air can cause mold and mildew to grow inside homes, which has various health risks. Very high humidity levels are also unpleasant for human beings, and can cause unsightly condensation. Dehumidifiers are useful in a variety of situations including new buildings, and buildings which have been subject to flooding.

Portable air conditioners come in three forms, split, hose exhaust, and evaporative. The main uses/advantages of Portable Air Conditioning are:

• It is portable, and thus location can be easily changed.
• Temporary – in areas where air conditioning might not normally be needed, but there is a temporary requirement.
• Emergency – portable air conditioning units can be supplied as emergency backup, in case of fixed air conditioning failure – especially critical in such areas as IT, Data Centres and Server Rooms.
• If a permanent solution where fixed air conditioning is not possible.