Getting the size of your air conditioner right is one of the most important decisions in any install. Too small and it’ll run flat out and never quite cool the room; too big and it’ll short-cycle, waste power and leave the air clammy. Here’s how sizing works for Brisbane homes and a rough guide to get you in the ballpark.
How air conditioner sizing works
Air conditioner capacity is measured in kilowatts (kW) of cooling (and heating). The right capacity depends mostly on the size of the room, but several other factors matter too. The goal is to match the unit to the space so it runs efficiently and comfortably.
A rough room-by-room guide
As a general starting point for a Brisbane home with average insulation:
- Small bedroom or study (up to ~20m²): around 2.5kW
- Larger bedroom or small living area (20–30m²): around 3.5kW
- Living/dining area (30–45m²): around 5–6kW
- Large open-plan area (45–65m²): around 7–9kW
These are starting estimates only — the right unit for your home may differ once the full picture is considered.
Factors beyond room size
In Brisbane’s climate, these all push the required capacity up or down:
- Windows and orientation — large or west-facing windows let in a lot of afternoon heat.
- Insulation — a well-insulated home holds temperature far better.
- Ceiling height — high or raked ceilings mean more air to condition.
- Room use and occupancy — kitchens and busy living areas generate more heat.
- Sun exposure and shading — an unshaded north or west room needs more grunt.
Why bigger isn’t better
It’s a common mistake to think a larger unit is the safe option. An oversized air conditioner cools the air quickly then switches off before it has removed humidity, leaving the room cold but clammy — and the constant on-off cycling wastes power and wears the unit. Correct sizing is about comfort and efficiency, not just power.
Get it sized properly
The only way to be sure is a proper assessment of your space. Integrated Trade Services will measure up, factor in your home’s specifics, and recommend the right system — whether split or ducted. Explore our air conditioning services or call 0400 775 002 for advice and a free quote.