The short answer
The most common air-con questions come down to cost, the law and care. A single split costs roughly £1,500–£3,000 installed; a 2.5 kW unit runs at about 15–25p per hour; only an F-Gas-certified engineer may install or service refrigerant systems; planning permission is usually not needed within permitted-development limits; and a well-maintained system lasts about 10–15 years. This page answers the rest and links to the detail.
This page gathers the questions people ask most about home and commercial air conditioning and answers them accurately, in plain English, with the key 2026 figures and legal facts. It is a quick reference and a map: each answer points to the fuller guide if you want the detail behind it. As ever, it is general information, not a substitute for a survey or quote from a certified installer.
Key facts at a glance
- Single split installed £1,500–£3,000
- Running cost (2.5 kW) About 15–25p per hour
- Service cost £80–£150 per unit
- Who may install F-Gas-certified engineers only
- Planning permission Usually not, within PD limits
- Typical lifespan About 10–15 years
Cost and running cost
The two questions that come up most are what air conditioning costs to buy and what it costs to run. On installation, a single split system typically costs £1,500–£3,000 fitted, a multi-split £3,000–£6,000+, and a portable unit £300–£600 — see installation cost. On running cost, a typical 2.5 kW split draws roughly 0.6–1.0 kWh per hour, which at around a 25p/kWh unit rate is about 15–25p per hour. Modern inverter units are markedly cheaper to run than older fixed-speed ones, because they modulate their output rather than switching fully on and off, and good maintenance keeps the figure down. The headline price of a unit is only part of the story: how efficient it is, how well it is sized to the room, and how it is used all shape the lifetime cost far more than the sticker.
| Question | Short answer |
|---|---|
| What does a single split cost? | About £1,500–£3,000 installed |
| What does it cost to run? | Roughly 15–25p per hour for a 2.5 kW unit |
| What does a service cost? | About £80–£150 per unit |
| What does a re-gas cost? | About £100–£300, after a leak repair |
| How long does it last? | About 10–15 years, well maintained |
The law and installation
Air conditioning is more regulated than many people expect. Under GB F-gas law, only an F-Gas-certified engineer, from a registered company, may install, commission, service or decommission a refrigerant system — DIY installation is illegal, and so is any DIY refrigerant work on an existing unit. On planning, a domestic external unit usually does not need permission if it meets permitted-development limits on siting and size, but conditions apply — and conservation areas and listed buildings are stricter, so always check before fitting. Larger and commercial systems also carry a legal F-gas leak-check duty above set refrigerant thresholds, with records kept. None of this is optional fine print: it is the framework that keeps installations safe, legal and properly documented, and it is one reason to use only a certified installer.
- Installation — certified engineers only; never DIY refrigerant work.
- Planning — usually permitted development for a domestic unit within limits.
- Leak-checks — a legal duty above set refrigerant thresholds, mainly on larger systems.
- Removal — refrigerant must be recovered, not vented, by a certified engineer.
Servicing, problems and care
On upkeep, most homes need a service about once a year at £80–£150 per unit, with filter checks in between — see servicing explained. The most common problems have simple first checks. Weak cooling usually means a dirty filter or a low charge from a leak; water leaks usually mean a blocked condensate drain; and smells usually mean damp or mould inside the unit — with one exception, a burning or electrical smell, which means switch the unit off at once and call an engineer. A re-gas, at £100–£300, should always follow a leak repair rather than be a routine top-up, because a sealed circuit does not consume refrigerant: if it is low, it is leaking.
Where to go next
If you are choosing a system, start with what size air con do I need, since sizing drives both comfort and running cost. If you are ready to buy, see how to get a quote and get matched with a certified installer who will survey the property first. If you already own a system, the servicing and troubleshooting guides keep it efficient and reliable, and the maintenance routine of yearly servicing plus filter checks in between is the single best way to protect your investment. Every figure here is a typical 2026 market range or a Tier-1 legal fact; this page is general information, not a substitute for a survey or quote from an F-Gas-certified installer.
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Frequently asked questions
How much is air conditioning in the UK?
A single split is roughly £1,500–£3,000 installed, a multi-split £3,000–£6,000 or more, and a portable unit £300–£600. Running a 2.5 kW unit costs about 15–25p per hour.
Do I need planning permission for air-con?
Usually not for a domestic external unit that meets permitted-development limits on siting and size, but conditions apply and conservation areas and listed buildings are stricter.
Can I install air conditioning myself?
No. Installing a refrigerant system is legally restricted to F-Gas-certified engineers. DIY installation is illegal and voids the warranty.
How long does air conditioning last?
A well-maintained system typically lasts around 10 to 15 years. Annual servicing is the biggest factor in reaching or exceeding that.
Sources & further reading
- GOV.UK — F-gas: guidance for users, producers and traders
- GOV.UK / Planning Portal — air conditioning and permitted development
- Energy Saving Trust — heating and cooling costs and efficiency
- The Fluorinated Greenhouse Gases Regulations 2015 (GB F-gas)
This guide is general information, not a site-specific survey or a substitute for a quote from an F-Gas-certified installer. Installation, servicing and refrigerant handling are legally restricted to F-Gas-certified engineers.