How the calculator works
What goes into your air conditioner size estimate?
The calculator estimates how much heat enters one room on a hot day. It then suggests a common unit size and estimates energy use and running cost.
Your room
We use the floor area, ceiling height, windows, insulation, outside walls, number of people and whether the room has a roof above it. Each of these can change how quickly the room heats up.
Outdoor temperature
We look up recent weather for your location when it is available. For the size estimate, we test the room against 30°C in the UK and 35°C in the US. This makes the result a rough guide, not a final system design.
Energy use and running cost
We estimate how much electricity the unit may use from the room result, your daily hours and an assumed unit efficiency. We multiply that by the electricity price you enter. Your real cost will depend on the unit, weather and how you use it.
Solar panels
If you enter your solar panel size, we estimate how much of the cooling electricity may be covered during daylight. We use stored solar data for the location when it is available. Otherwise, we use a broad UK or US estimate.