Higher ceilings mean more air to heat or cool. For every 300mm above a standard 2.4m ceiling, we recommend increasing your air conditioner’s capacity by 10%. 

Example:
If your room has a ceiling height of 3.0m, that’s 600mm above the standard 2.4m.
To calculate the extra capacity needed:

• Add 10% per 300mm above 2.4m.

• So, 600mm = 20% extra capacity.

If a standard room needs a 5.0kW unit, your room may require a 6.0kW unit (5.0kW + 20%).

Good insulation in the roof, walls, windows, and doors makes a big difference. Poor insulation allows heat to enter in summer, and escape in during winter. This requires a larger unit to maintain a comfortable temperature year-round.

Example:
A lounge with no roof insulation and uninsulated glass doors will struggle to maintain temperature. Even a small room might need to size up from a 2.5kW unit to a 3.5kW to compensate for heat gain/loss.

The more glass windows and doors you have, the more heat or cold will transfer between indoors and outdoors – especially if they’re large, uncovered, or unshaded. This makes it harder for your air conditioner to work efficiently.

Example:
A small bedroom with two large north-facing windows and higher ceiling will heat up quickly in Summer. You may need a 2.5 – 3.0kW unit instead of the standard 2.0kW, despite the room’s size. 

Internal walls, corners, and partitions can limit the natural flow of air, meaning the cool or warm air from your unit doesn’t reach every part of the room evenly. A more powerful unit – or multiple units – may be needed in complex layouts.

Example:
An open kitchen and dining area with a partial dividing wall may restrict airflow. A larger unit or a multi-split system may provide more even temperature control across the space.

Where you live has a big impact on your air conditioning needs. Homes in hot or cold climates require higher-capacity units to keep indoor temperatures stable, even if the room size is the same as those in temperate climates.

Example:
If you live in Far North Queensland, where summer temperatures reach 35°C+, a 3.5kW unit that’s suitable for a room in Melbourne may need to be upgraded to a 5.0kW unit to cope with the heat.

Your home’s position and exposure to sunlight affect how much heat it absorbs during the day. A north-facing room receives more direct sun, making it warmer and harder to cool in summer.

Example:
A north-facing living room with large windows can become a heat trap. Even if it’s insulated, the increased solar load means you’ll likely need a higher kW system to maintain a comfortable indoor climate.