1. Your answers and our assumptions
The journey collects size information for each room, including a size band or dimensions where supplied, plus room type and sunlight. It also asks about the property, permission and practical installation conditions. These are homeowner answers, not verified site measurements.
A size band uses a representative area, not a measured floor area. If you enter length and width, we multiply them to find the floor area. In both cases, ceiling height is assumed to be 2.4m; the journey does not measure or collect it.
Unknown room size and rooms over 50m² do not receive an online capacity or price. They need a tailored review. Other uncertainties can produce survey flags alongside an indicative result. When any room cannot be sized, the whole-home price and running-cost totals are withheld rather than showing a partial figure as the total.
2. Indicative cooling capacity
The baseline is 40 watts per cubic metre. The model uses room volume, then applies room-type and sunlight factors. It does not infer insulation or building age from the property type, so no property-type heat multiplier is applied.
Little direct sun uses a factor of 0.9, some sun 1 and a lot of sun 1.2. Unknown sunlight uses 1 provisionally and raises a review flag. Room-type factors are also assumptions, not measured heat gains: a bedroom uses 1, while higher-load types such as kitchens, lofts and conservatories use larger factors.
Cooling load in kW = room volume in m³ × 40 × applicable factors ÷ 1,000
The lower and upper load scenarios use 85% and 120% of the central calculation before rounding upwards to the supported capacity bands: 1.5 kW, 2 kW, 2.5 kW, 3.5 kW, 5 kW, 6 kW, 7 kW, 9 kW. These are model scenarios, not statistical confidence limits.
If the required load exceeds the supported maximum of 9 kW for a room, it needs a survey rather than a capped figure presented as sufficient. A capacity band is not a specific product recommendation.
An installer must assess the real heat gain, including glazing, shading, insulation, occupants and equipment. They also confirm suitable unit positions, electrical supply, drainage, noise and access.
3. Indicative installation ranges
Each supported capacity maps to an internal supply-and-fit price band. These bands are assumptions in the model, not live installer offers or a measured market average. The existing complexity allowances are £0 for basic, £200 for standard and £450 for complex access. They do not price every possible complication.
For multiple rooms, the estimate sums separate-system ranges: one indoor/outdoor split-system allowance per room. It does not add another £900 per extra room. It is not a multi-split quote, where several indoor units share an outdoor unit. Your installer may propose a different design and price.
Long pipe runs, scaffolding, electrical upgrades, structural work and other site conditions need individual pricing. Do not assume they are included in an allowance. Ask the installer to state equipment, labour, VAT treatment, exclusions and any permissions in their written quote.
Worked one-room example
- Inputs
- 16m² room, 2.4m assumed ceiling, neutral factors
- Assumed volume
- 38.4m³
- Raw central load
- 1.536 kW
- Rounded capacity range
- 1.5 to 2 kW
- Standard complexity range
- £1,800 to £2,800
This is the same constructed scenario used on the homepage, not a completed job or a price promised for your home.
4. Cooling running costs
The simplified electricity model divides cooling output by an assumed seasonal efficiency (SEER), then multiplies by the hours of use and electricity tariff. The defaults are SEER 6 and 27p/kWh. The tariff is an editable assumption, not a statement of today's regulated price.
Cost = cooling kW ÷ SEER × hours per day × days × electricity price per kWh
Whole-home examples combine the output of the selected rooms, not only the largest unit. This assumes those rooms run for the same hours. It can overstate cost if only one room is used at a time, and does not model the detailed efficiency of a particular multi-split system.
| Scenario | Per hour | 225 hours |
|---|---|---|
| One 2.5 kW room | 11.25p | £25.31 |
| Two 2.5 kW rooms together | 22.50p | £50.63 |
SEER is a seasonal rating, not a promise of hourly efficiency. Weather, temperature settings, cycling, maintenance and the actual system all affect consumption. This example is not a measured electricity bill or a guaranteed upper limit.
Adjust the single-system running-cost example. If your rooms run on different schedules, calculate each separately and add their costs.
5. What happens after the estimate
Coverage is a separate check of currently eligible installers listing your postcode, not part of the sizing calculation and not confirmed appointment availability.
If you choose to request introductions, an independent installer assesses the property and gives you a written quote. Confirm planning, landlord or freeholder requirements with the installer and the relevant authority for your property. The online answers do not establish permission.
CoolMatch is responsible for its introduction service. Your chosen installer is responsible for their survey, design, work and agreed aftercare. The estimate is not an installation contract.
Installer radius maps
The radius tool selects postcode districts whose centre points fall within 1 to 50 straight-line miles of your base district's centre. It does not use your exact address, district boundaries, roads or travel times. Some addresses in a selected district can be beyond the circle. Check the list and edit it to fit where you actually work.
The circle tool covers Great Britain. Northern Ireland and Crown Dependency districts can be entered manually; they are not included in this map dataset. A geographic circle does not indicate demand, available jobs or approved installer coverage.
District coordinates come from doogal.co.uk, using ONS geography. Contains OS data © Crown copyright and database right 2026. Contains Royal Mail data © Royal Mail copyright and database right 2026. Contains National Statistics data © Crown copyright and database rights 2026. Source: Office for National Statistics, licensed under the Open Government Licence v3.0. Retired and explicitly non-geographic records are excluded. The source is checked periodically and can omit recently created districts.
Google Maps loads automatically on the working-area step after CoolMatch finds a valid district centre for your postcode. It shows that centre and your radius. Pan and zoom do not change the base or postcode list; Google does not calculate the list or fetch driving routes. Device location is not used. Google attribution and controls stay visible. If the map cannot load, enter districts manually. See Map privacy.