Get the size right and your air conditioning will cool quickly, run quietly and cost less to run. Get it wrong and it either struggles on hot days or wastes energy. Here’s how sizing works.
What kW means
Air conditioning output is measured in kilowatts (kW). The higher the number, the more heat the unit can move out of a room. It’s about capacity, not how much electricity it uses.
A quick guide by room
Room
Typical size
Average UK bedroom
Around 2.5 kW
Living room
Typically 5–7 kW
Kitchen or open plan
Typically 5–7 kW
Home office or garden room
Confirmed at survey
What changes the size
- Room size and ceiling height
- How much glazing there is, including roof lights
- Which way the room faces
- How well the room is insulated
- How many people and appliances are usually in it
Engineer’s tip
A south-facing bedroom with a big window can need more cooling than a larger north-facing one. That’s why rules of thumb are only a starting point.
Why we survey first
Every Coolhome quote starts with a free home survey. We measure each room, check the walls and windows, and agree where the units will go. You get a fixed price for the right size of system, not a guess.
Not sure what size you need?
We’ll measure up for free, with no obligation.
