Do you really need an air conditioner?
 
Do you really need an air conditioner?The first step's insulating your ceilings (and walls if possible).
Shading for east, north and west-facing windows helps prevent the sun's heat from entering your home; outside shading is more efficient than internal blinds or curtains.
Draughtproof your home.
Avoid activities that produce heat during the day.
Wear light clothing made from natural fibres.
Try fans for a cooling effect.
If you live in a hot and dry climate, an evaporative air cooler may be a cheaper alternative than an air conditioner.
Buying the right type

If you've decided an air conditioner is worth buying, you need to decide which type best meets your requirements. They come as portable units, wall or window units, split systems where the compressor is installed outside the house and the air outlet(s) inside, and ducted systems with an outside compressor and several ducts inside into as many rooms as you like.

There are cooling-only and reverse-cycle models. Reverse-cycle air conditioners usually only cost a little bit more than cooling-only ones of similar capacity, and provide very efficient electric heating.

Getting the right size is the next step. Use our cooling and heating capacity calculators to find out what you need.

Finally, compare the energy-efficiency rating of the models with the capacity you need. Air conditioners are very efficient. For every kW of electricity consumed, two or more kW of heating or cooling capacity can be produced. However, there are still differences between models.

Air conditioners up to 7.5 kW cooling capacity must carry an energy rating label ¡ª the more stars a model has, the more efficient it is, and the lower its running costs.

The efficiency of larger models (most ducted systems) is expressed as the cooling co-efficient of performance (COP) or the energy efficiency ratio (EER) ¡ª the ratio between the cooling capacity (in kW) and the amount of electricity used in the cooling process (in kW). The higher the value, the more efficient. An efficient system can save you hundreds of dollars in running costs each year compared to a less efficient one.
Portable unitsPortable air conditioners use the same heat-exchange principle as built-in models. So they can cool and dehumidify the air. As they're not installed to a wall or window, you can move them around from room to room ¡ª for example, use them in your living room during the day, and in your bedroom at night.

Portable air conditioners: We tested five models. Only three were able to cool our test room by a reasonable amount. The other two are only suitable as spot or personal coolers. For a similar price, you can get an installed window/wall or even split-system air conditioner, which will give you better performance. The article is free.
Split-systems

Reverse-cycle air conditioners (2.5 - 3.0 kW): We tested four inverters and four non-inverters suitable for a large bedroom or small living area. The report is free for members, and $9.95 for non-members.
Reverse-cycle air conditioners (6.8 kW): We tested six models with 6.5 to 7.2 kW claimed cooling capacity - suitable for a large open-plan living area. The September 2003 report is free for members, and $9.95 for non-members. Want to become a member? Find out more .
Ducted systemsDucted reverse-cycle air-conditioning can be a very convenient way of cooling and heating your home.

A ducted air conditioner consists mainly of a heat pump (1), ducting (2), vents (3) and a return air vent (4).

With a central cooling or heating system, the right size and design depend on a range of parameters, such as your home's floor plan, the size and orientation of windows or level of insulation. The system has to be designed by your installer for your individual situation, and shouldn't be bought "off-the-shelf".