Solar panels, heat pumps and insulation in Pinner / West Towers conservation area
In the Pinner / West Towers conservation area (Harrow), 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 Harrow covers part of this area (about 1% of it) and removes permitted development rights for replacement windows and doors, and other alterations to the house, so there these need planning permission too. 37 homes inside the boundary have an energy certificate: 11% are solid-wall homes with no wall insulation, 97% heat with a gas boiler and 89% are rated D–G; 0 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
37homes with an energy certificate
11%solid walls, no insulation
97%heated by a gas boiler
0heat pumps
Article 4: An Article 4 direction published by Harrow covers part of this area (about 1% of it) and removes permitted development rights for replacement windows and doors, and other alterations to the house, so there these need planning permission too. (Residential extensions)
What needs planning permission in Pinner / West Towers
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
Inside the Article 4 part of the area: planning permission needed; elsewhere: no permission needed (permitted development)
Part 1 Class A, A.3(a)
Listed buildings: none recorded inside the boundary; on a listed building, solar panels and heat pumps are not permitted development and need listed building consent.
Flats: 0% 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 = 37)
Walls
Homes
Share
Cavity wall, unfilled
21
57%
Cavity wall, filled
12
32%
Solid wall (brick or stone), no insulation
4
11%
Heating
Homes
Share
Gas boiler
36
97%
Solid fuel (wood, coal)
1
3%
Loft / roof insulation
Homes
Share
No insulation
4
11%
Under 200 mm
22
59%
200 mm or more
7
19%
Insulated (depth not recorded)
4
11%
Windows
Homes
Share
Double glazed
31
84%
Single glazed
4
11%
Secondary glazing
2
5%
CDE
Energy rating: C 4 (11%) · D 21 (57%) · E 12 (32%). Houses and bungalows: 100% of the homes; solar panels on 0% of the certificates. Most common build period on the certificates: 1930-1949.
Compared with Harrow and England
Share of homes
Pinner / West Towers
All 31 areas in Harrow
England
Solid walls, no insulation
11%
55.6%
48.7%
Gas boiler
97%
90.9%
66.4%
Rated D–G
89%
—
56.5%
Caveats
Certificates describe a home when it was assessed; 54% of these are from 2020 or later (latest 24 February 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 Harrow if in doubt.
Boundary: London Borough of Harrow via planning.data.gov.uk (entity 44008801, reference 174_HRW_CA14, 2.9 ha); the council's appraisal or map. Homes are placed by the coordinates of their UPRN (OS Open UPRN); addresses are not shown.