Climate control, or air conditioning, balances the temperature, humidity, air motion and radiant temperature so our bodies can dissipate the excess heat we generate at the correct rate. In other words, a room conditioned to an ideal temperature feels neither too hot nor too cool. There are two ways to achieve this: by central or room air conditioning.
As the name suggests, central air conditioning works from a large electrical refrigerating mechanism with a system of ducts, which enable the central system to cool or heat the entire house. A room air conditioner does virtually the same job of lowering temperature and humidity and filtering the air. If it has a reverse cycle, it also heats the air. These units are designed to heat only one or two rooms. They are usually installed in a window.

How it works.
There are two main types of air conditioners and both cool a room by evaporating liquid at low temperature. Heat extracted from the air is used to change the liquid to a vapor.

Refrigerated - these coolers use a liquid called a refrigerant, which is recycled within the system. Heat extracted from the air is rejected from a condenser into the outside air.

Refrigerated coolers need energy to condense the vapor back into a liquid, and so they use more power than evaporative coolers. Refrigerated coolers are most suitable in humid conditions where they actually reduce humidity in the room. Water from the air condenses as dew on the cool evaporator surface, the dew drains away and is discarded outside.

Some units are called "split,' systems because the condensing section is separated from the evaporating section. Only pipes carrying the refrigerant connect them. This reduces the noise in the room and surroundings.

Most refrigerated units are fitted with air filters and some models can bring in fresh air or exhaust stale air.

Evaporative - these are the simplest type of coolers and they evaporate water. Heat required to evaporate the liquid is taken away from the incoming air stream, making it cooler. The water vapor passes into the room with the air and may increase humidity. This is why evaporative coolers are preferred in drier regions, and less suitable in areas where the relative humidity is high.

These coolers work best with dry air so a mobile unit should be placed near a partly open window, where it can draw in air from outside. This means the cooler also provides ample ventilation.

The capacity of an air conditioner to heat or cool a room is described in B.T.U-s (British Thermal Units). The metric measurement is the kilowatt-hour. 3412 BTU’s are equal to 1 kilowatt hour.

Choosing the right unit.
Central systems - discuss your requirements with experienced air conditioning advisors, and preferably obtain several quotations from reputable suppliers. They will take into account the size of the house and individual rooms, number and orientation of windows, construction materials, number of occupants and such factors as trees and shrubs surrounding the house.

Room air conditioners - preferably have an expert inspect the room where you plan to install the unit. Failing that, take a room plan with you showing the size of the room, orientation and number of windows, and any other information which might be helpful.

Solar air conditioning is also very popular. Contact your local expert for more details and advice if you are considering installing one of these units.

Maintenance.
This is usually fairly straightforward. In most units, the filter should be checked every month or so during the cooling season. Airborne material such as dust, leaves and insects can clog the condenser, which should be checked occasionally by a serviceman. Evaporative coolers are also affected by airborne material and the quality of water in a particular area. Evaporative pads and components should be checked for wear at least yearly. With both types of units, follow the maintenance instructions supplied by the manufacturer. Having the unit professionally serviced at intervals is a small price to pay for long life and efficiency, to say nothing of the increased comfort of living in an air-conditioned environment.