Factors to Consider When Choosing the Capacity of Your Home Air Conditioner

Posted on: 17 September 2020

When purchasing an air conditioner, it can be tricky to work out what size to go with. You might have seen guides that marry a specific capacity to a particular room size. While these can be excellent indicators, you need to take other factors into account also. Ask your contractor for their advice, but to get started, consider the following determinants that can influence how much cooling power you'll require.

Local Climate

Imagine two rooms of similar size with comparable windows, one in Perth and the other in Hobart. Of course, their requirements for air conditioning will be different because of their respective climates. With hot summers, Perth properties will have greater cooling needs than Hobart ones. Thus, taking room dimensions only into account when picking the capacity of a system will not be totally accurate — it's too simplistic and leaves out many other relevant factors, such as local climate.

Window Size and Orientation

In a room, one of the main ways that heat from the sun can enter is via glass, whether it be in windows or doors. It may be lovely to open up your home to outside with glass, but you'll pay a price in terms of your home's energy efficiency. It's not only the size of windows that's important, but also their orientation. West-facing windows, in particular, can bake in the hot afternoon sun, as can north-facing openings. If the room you're cooling has windows on a southerly wall, though, they'll typically allow less heat to enter than other orientations. Your evaluations also need to consider whether your home has double-glazed or low-E glass that hinders heat gain.

Window Coverings

Window coverings are another factor that can significantly affect how much heat a window emits and how hot a room tends to get. Are your windows fitted with shutters with inbuilt insulation in the louvres, for instance? Reflective exterior awnings are another way to reduce radiant heat that enters a room when sun rays strike the glass. Many window coverings will specify how much heat they can deflect, and you can use these as a guide. Ultimately, such factors will help you to determine what the best size air conditioner is for you. 


Is the room you intend to cool insulated in the walls or roof? An insulated room will allow far less outside heat to enter and thus lower your cooling requirements. The exterior wall and roof cladding play roles also, as some materials allow heat to flow freely through while other substances don't.

Your air conditioning contractors, who would have cooled places with many different variables, will be able to advise on an appropriate capacity unit for your home, taking everything into account.

To learn more, contact an air conditioning company.