Solar panels, heat pumps and insulation in Coppermill Lock conservation area
In the Coppermill Lock conservation area (Hillingdon), external wall insulation needs planning permission, and so does an air source heat pump on a wall or roof facing the road; one at the back or side, internal and loft insulation and solar panels on a roof slope normally do not. An Article 4 direction published by Hillingdon covers this area and removes permitted development rights for replacement windows and doors, and other alterations to the house, so there these need planning permission too. The area has 3 listed buildings; on a listed building solar panels and heat pumps are not permitted development at all and need planning permission and listed building consent. 108 homes inside the boundary have an energy certificate: 6.5% are solid-wall homes with no wall insulation, 61.1% heat with a gas boiler and 50.9% are rated D–G; 2 have a heat pump. EPC register November 2026; rules as at 21 October 2026.
Data: EPC register November 2026 (latest certificate per home), conservation area boundaries 3 November 2026, permitted development rules as at 21 October 2026 · calculated 5 November 2026 · Methodology and sources
108homes with an energy certificate
6.5%solid walls, no insulation
61.1%heated by a gas boiler
2heat pumps
Article 4: An Article 4 direction published by Hillingdon covers this area and removes permitted development rights for replacement windows and doors, and other alterations to the house, so there these need planning permission too. (Changes of use from commercial, business and service uses to dwellinghouses; Construction of new dwellinghouses in employment areas; Residential extensions)
What needs planning permission in Coppermill Lock
Work (house, not listed)
In a conservation area
Rule
Air source heat pump on a wall or roof facing the road, or nearer the road than the house
Planning permission needed
Part 14 Class G, G.1(j)
Air source heat pump at the back or side (outdoor unit up to 1.5 m³, MCS Planning Standards, one per house — two on a detached house)
No permission needed (permitted development)
Part 14 Class G
Solar panels on a pitched roof (up to 0.2 m proud, not above the ridge)
No permission needed (permitted development)
Part 14 Class A, A.2(c)
Solar panels on a wall, balcony or roof enclosure facing the road
Planning permission needed
Part 14 Class A, A.2(e)
Solar panels on a flat roof (up to 0.6 m above the roof)
Replacement windows and doors of similar appearance
Planning permission needed (an Article 4 direction here removes this right)
Part 1 Class A, A.3(a)
Listed buildings: 3 in the area. The table is for houses that are not listed: on a listed building, solar panels and air source heat pumps are not permitted development at all (they need planning permission), and any of these works needs listed building consent.
Flats: 45% of the certified homes here are flats or maisonettes. Homes in a block of flats have no householder rights for alterations; heat pumps and solar have their own, tighter rules for blocks of flats.
The homes in the area (latest certificate per home, n = 108)
Walls
Homes
Share
Modern wall (U-value from the design)
54
50.0%
Cavity wall, insulated (as built or unspecified)
28
25.9%
Solid wall (brick or stone), no insulation
7
6.5%
Solid wall, insulated
5
4.6%
Solid wall, internal insulation
5
4.6%
Timber frame
4
3.7%
Cavity wall, filled
2
1.9%
Cavity wall, partly insulated
1
0.9%
Cavity wall, unfilled
1
0.9%
Other or not known
1
0.9%
Heating
Homes
Share
Gas boiler
66
61.1%
Electric (storage heaters, panels, boiler)
37
34.3%
Heat pump
2
1.9%
Oil
2
1.9%
Solid fuel (wood, coal)
1
0.9%
Loft / roof insulation
Homes
Share
No insulation
1
0.9%
Under 200 mm
24
22.2%
200 mm or more
6
5.6%
Insulated (depth not recorded)
14
13.0%
Flat or other home above
24
22.2%
Other
39
36.1%
Windows
Homes
Share
Double glazed
104
96.3%
Single glazed
4
3.7%
BCDE
Energy rating: B 25 (23.1%) · C 28 (25.9%) · D 37 (34.3%) · E 16 (14.8%) · F 2 (1.9%). Houses and bungalows: 55% of the homes; solar panels on 0.0% of the certificates. Most common build period on the certificates: 2016.
Compared with Hillingdon and England
Share of homes
Coppermill Lock
All 32 areas in Hillingdon
England
Solid walls, no insulation
6.5%
25.5%
48.7%
Gas boiler
61.1%
62.7%
66.4%
Rated D–G
50.9%
—
56.5%
Caveats
Certificates describe a home when it was assessed; 27% of these are from 2020 or later (latest 19 October 2026). “No insulation (assumed)” is the assessor's default for older walls.
The rules are England's national permitted development rules (General Permitted Development Order 2015, Schedule 2, as at 21 October 2026). They do not cover building regulations or a council's own conditions. This is not a planning decision: ask Hillingdon if in doubt.
Boundary: London Borough of Hillingdon via planning.data.gov.uk (entity 44008921, reference COA00000500, 10.0 ha). Homes are placed by the coordinates of their UPRN (OS Open UPRN); addresses are not shown.