Can a loft conversion have an outdoor unit on the wall?
A loft conversion can still be permitted development on a rear wall that does not face a highway (Class G, G.2(k), checked 25 Sep 2026). The highway-facing wall above the ground floor is the case Class G leaves out.
computed
Worked case from the decision engine
Result on the facts named above: permitted development.
Worked rear wall, above the ground floor, not facing a highway: permitted development. The same facts on a highway-facing wall: planning permission needed. A pitched-roof mount is outside Class G on its own sentence.
Volume, noise and listing in the worked case are entered facts. They are not read off the postcode.
Cooling paths
At 400 hours and the Ofgem cap, the split scenario is £27.71 and the portable scenario delivering the same 2.5 kW is £101.23.
| Path | What it is | Up front | £ for 400 h | Open |
|---|---|---|---|---|
| External shading | No outdoor unit | Shelf prices sit in the shade class of the retail file | No compressor draw in the catalogue | /tools/sizing/ |
| Fan | Devola Low Noise 20W 9 Speed 9-inch DC Desk Fan - White - DVF7DCFAN | £59.95 | £2.11 for 400 h at 20 W | /tools/running-cost/ |
| Portable | Cirro® 12000 BTU Super Quiet Smart Portable Air Conditioner - Cooling | £519.99 | £101.23 to deliver 2.5 kW for 400 h at EER 2.6 | /tools/running-cost/ |
| Split / air-to-air | Daikin Perfera 2.5 kW, SEER 9.5 | median shelf £1,027.49 (n=14) | £27.71 for 400 h | /tools/payback/ |
The clauses this situation turns on
ENG-11 · G.2(k) · checked 25 Sep 2026. in the case of land, other than land within a conservation area or which is a World Heritage Site, the air source heat pump would be installed on a wall of a dwellinghouse or block of flats if—(i) that wall fronts a highway; and (ii) … above the level of the ground floor storey Source
ENG-06 · G.2(f) · checked 25 Sep 2026. the air source heat pump would be installed on a pitched roof Source
Next pages
· · n= · · updated 25 Sep 2026 · version 1.0.0 · CSV of the values on this page