Home/Running costs
23° Running costs
Less than you think.
Work it out.
Modern inverter units ramp down once the room reaches temperature, so the average draw is far below the number on the label. Drag the slider for a rough figure for your room and your tariff; your quote shows the real one.
22° The calculator
Your room, your tariff.
Estimated cost to run
£1.51a day
Over a month£45 a month
Average draw once at temperature0.7 kW average
Electricity used5.6 kWh a day
An estimate for comparison, not a quote. Average draw figures are typical for inverter wall splits once the room is at temperature; the unit works harder for the first half hour and on the hottest afternoons, and less on cooler days. Change the pence figure to match your tariff.
22° At 27p a unit
Three rooms, side by side.
The same figures as the calculator, at 27 pence per kilowatt-hour, for a night's cooling. Your tariff will differ; it is printed on your bill.
| Room | Unit | Average draw | Per hour | 8 hours a night | Month of nights |
|---|---|---|---|---|---|
| Small bedroom | 2.5 kW | 0.5 kW | 14p | £1.08 | £32 |
| Double bedroom | 3.5 kW | 0.7 kW | 19p | £1.51 | £45 |
| Living room | 5 kW | 1.1 kW | 30p | £2.38 | £71 |
Heating for a third
In heating mode the unit moves about three units of heat for each unit of electricity. The same 3.5 kW unit heating a garden office uses roughly a third of what a fan heater giving the same warmth would.
Half an hour ahead
The timer is the cheapest feature on the remote. On thirty minutes before bed, off at 2 am once the room has settled, and the house stays comfortable for a fraction of the cost of all night.
Clean filters, lower bills
A clogged filter makes the fan work harder and the unit run longer. Rinsing the mesh filters once a month in summer takes two minutes and keeps the running cost where it should be.
21° Straight answers
Things people ask about the cost.
Why is the average draw so much lower than the label?+
The label shows the maximum input, which an inverter unit only uses while it is pulling the room down to temperature. Once the room is there it throttles the compressor back and sips power to hold it. Over an evening the average is typically a fifth to a third of the label figure.
Is it cheaper to leave it on all day?+
No. The cheapest pattern is a timer: on half an hour before you need the room, off when you leave. Cooling an empty room is wasted money; cooling a hot room from scratch at bedtime costs less than holding it cool all afternoon.
What does heating cost?+
Heating is where the system earns its keep. For every unit of electricity it moves roughly three units of heat into the room, so a 3.5 kW unit heating a garden office uses about a third of what a fan heater of the same warmth would.
Will my bill actually go up by this much?+
These are estimates for comparison with your tariff. Real use depends on the weather, how cool you like it and how well the room holds temperature; the fixed quote comes with a running-cost note for your room.
Want the real number for your room?
The fixed quote comes with a running-cost note worked out for your room, your glazing and your tariff.
21° Let's get you here
Free survey.
Fixed quote.
Cool by the weekend.
- A free home survey, usually within a few days.
- A written, fixed quote the same day as the survey.
- Most single rooms fitted and commissioned in one visit.
- Our own engineers, F-Gas registered, no subcontractors.
It answers day and night and can talk you through what would suit the room.