Planning & regulations
No planning permission. No external units. No problem.
Our fan coil units install entirely inside your loft. They connect to your existing heat pump's water circuit — no new external equipment, no external alterations, no planning permission required.
The problem
Already have a heat pump? A second external unit needs planning.
Under UK permitted development rules, you're allowed one air source heat pump per property without planning permission (GPDO Part 14, Class G). If you already have a heat pump and want to add a split AC system for cooling, that's a second external unit — which means you need full planning permission.
Split AC system
- Requires an external condenser unit on the wall or ground
- Second external unit on a property = planning permission needed
- Noise restrictions may apply (MCS 020 / 42 dB at nearest neighbour)
- Visual impact on the building exterior
- Listed buildings: almost certainly refused
- Conservation areas: additional restrictions
Fan coil system
- Entirely internal — unit sits in the loft
- No external equipment, no external alterations
- No planning permission required
- No noise impact on neighbours (unit is inside)
- Uses your existing heat pump — no second unit
- Ideal for listed buildings and conservation areas
Listed buildings
The only option for listed buildings
If you live in a listed building and already have an approved heat pump installation, adding cooling is straightforward with fan coil units. Here's why:
No external alterations
Fan coil units install in the loft and duct to ceiling vents. The only visible change inside the property is a ceiling grille — which can be positioned discreetly and is typically no more intrusive than a bathroom extractor vent.
Uses existing infrastructure
The system connects to your existing heat pump's chilled water circuit. No new penetrations through external walls, no new external pipework, no new electrical supplies to the outside of the building.
No listed building consent needed
Because there are no external alterations and the internal changes are minimal and reversible, listed building consent is not typically required. As always, check with your local conservation officer if you're unsure.
Note: This is general guidance, not legal advice. Planning rules vary by local authority, and listed building requirements can be complex. If you're unsure, contact your local planning authority or conservation officer before proceeding. We're happy to provide technical information about the installation to support any enquiries.
The rules
UK permitted development — what you need to know
Air source heat pumps (GPDO Part 14, Class G)
Permitted development allows one air source heat pump per property without planning permission, subject to conditions including:
- Must comply with MCS 020 planning standards
- Volume of the unit must not exceed 0.6 m³
- Must be at least 1 metre from the property boundary
- Not on a wall or roof fronting a highway
- Not in a conservation area, World Heritage Site, or AONB (additional restrictions apply)
- Unit must be removed when no longer needed
Second external unit = planning permission
If you already have a heat pump installed under permitted development and want to add a split AC system, that second external unit is not covered by permitted development. You would need to apply for full planning permission from your local authority. This adds cost, delay, and uncertainty — and there's no guarantee of approval, especially in conservation areas or for listed buildings.
Fan coil units — no external development
Fan coil units are installed entirely inside the property. They are not “development” in planning terms because there is no external alteration. No planning permission is needed regardless of how many units you install, whether you're in a conservation area, or whether the building is listed.
The only requirement is that your existing heat pump can produce chilled water — which virtually all UK air source heat pumps can.
At a glance
| Split AC | Fan Coil | |
|---|---|---|
| External unit required | Yes | No |
| Planning permission (with existing heat pump) | Required | Not required |
| Suitable for listed buildings | Very unlikely | Yes |
| Conservation area restrictions | Additional hurdles | None |
| External noise impact | Compressor noise | None (internal only) |
| Visual impact on building | External box + pipework | Ceiling vent only |
| Uses existing heat pump | No (separate system) | Yes |
Cool your home without the planning headache
Your heat pump already makes cold water. Our fan coil units turn it into cool air — entirely from inside your loft.