You know you need an air conditioner, but what size air conditioner do you need? Do you need a ducted air conditioning system or will a portable or wall mounted unit be enough? These are important questions that ultimately an air conditioning specialist in your area will best be able to help you answer, but this guide will help get you started on the right track.

What Does 'Air Conditioner Size' Mean?

When an air conditioning supplier talks about air conditioning size, they are not always talking about its actual physical size. In fact, they are probably talking about its capacity or the area that requires air conditioning. Before you start looking at air conditioners, it's a good idea to first determine whether or not you want to cool and/or heat the entire house or if air conditioning for just the living room or another room will suffice. If you just want to air conditioning for a single room, then you probably don't need a ducted system, but you still need to determine what size air conditioner you need.

What Size Air Conditioner Do You Need?

As mentioned above, when speaking of air conditioner size, you are really speaking about its capacity. An air conditioner's capacity is largely determined by the amount of energy output it is capable of producing. This is measured in kilowatts (kW). The greater the kilwatt output of an air conditioner, the greater the area it can cool (or heat and cool, in the case of a reverse cycle air conditioning system). How, then, do you determine what size air conditioner you need?

Although many other factors need to be considered, under normal conditions, it takes .125 kW of energy to cool 1 square meet of living space. If you have average height ceilings and a reasonably well insulated living room, you can get a rough idea of what size air conditioner you need by multiplying its area in square metres by .125. For example, if your room measures 6 metres by 8 metres (48 sq. metres), your air conditioner should have an output of 6kW in order to be able to cool the room efficiently.

When you start looking at air conditioners, you will see that they have cooling capacities of from less than 5kW to as high as 25kW. The majority of brands and models on the market today are within the 4 to 15kW range. Less than 5kW is sufficient for a smaller area, such as an apartment. Small to medium sized homes usually require something in the 5 to 9kW range while very large homes with vaulted ceilings may require an air conditioner size of 10 to 15kW.

Other Considerations

No matter what size air conditioner you buy, it will consume a significant amount of energy. You can significantly reduce your air conditioning energy consumption by blocking the sun's radiant heat with curtains, blinds and/or awnings. Double glazed windows, too, keep both heat and cold from penetrating into the house and UV blocking window tinting can make a dramatic difference in areas where the sun strikes a window or glass door directly. Take a holistic approach to air conditioning and you may find that a smaller air conditioner size will work as efficiently for you as a larger one would work in a less energy efficient home environment.