Solar panels, heat pumps and insulation in Barn Hill conservation area
In the Barn Hill conservation area (Brent), 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 Brent covers this area and removes permitted development rights for solar panels on the house, wind turbines on the house, replacement windows and doors, and other alterations to the house, alterations to the roof (e.g. rooflights), chimneys, flues and soil pipes, painting the outside, so there these need planning permission too. 478 homes inside the boundary have an energy certificate: 49.4% are solid-wall homes with no wall insulation, 99.0% heat with a gas boiler and 79.7% are rated D–G; 1 has 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
478homes with an energy certificate
49.4%solid walls, no insulation
99.0%heated by a gas boiler
1heat pumps
Article 4: An Article 4 direction published by Brent covers this area and removes permitted development rights for solar panels on the house, wind turbines on the house, replacement windows and doors, and other alterations to the house, alterations to the roof (e.g. rooflights), chimneys, flues and soil pipes, painting the outside, so there these need planning permission too. (Article 4 for HMOs; Barn Hill)
What needs planning permission in Barn Hill
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)
Planning permission needed (an Article 4 direction here removes this right)
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)
Planning permission needed (an Article 4 direction here removes this right)
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: none recorded inside the boundary; on a listed building, solar panels and heat pumps are not permitted development and need listed building consent.
Flats: 6% 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 = 478)
Walls
Homes
Share
Solid wall (brick or stone), no insulation
236
49.4%
Cavity wall, unfilled
144
30.1%
Cavity wall, filled
66
13.8%
Cavity wall, insulated (as built or unspecified)
8
1.7%
Modern wall (U-value from the design)
5
1.0%
Solid wall, external insulation
5
1.0%
Cavity wall, partly insulated
4
0.8%
Solid wall, internal insulation
4
0.8%
Solid wall, insulated
3
0.6%
Solid wall, partly insulated
2
0.4%
Cavity wall, internal or external insulation
1
0.2%
Heating
Homes
Share
Gas boiler
473
99.0%
Electric (storage heaters, panels, boiler)
3
0.6%
Communal heating
1
0.2%
Heat pump
1
0.2%
Loft / roof insulation
Homes
Share
No insulation
124
25.9%
Under 200 mm
192
40.2%
200 mm or more
110
23.0%
Insulated (depth not recorded)
41
8.6%
Flat or other home above
6
1.3%
Other
5
1.0%
Windows
Homes
Share
Double glazed
450
94.1%
Single glazed
22
4.6%
Secondary glazing
6
1.3%
CDE
Energy rating: B 3 (0.6%) · C 94 (19.7%) · D 237 (49.6%) · E 121 (25.3%) · F 21 (4.4%) · G 2 (0.4%). Houses and bungalows: 94% of the homes; solar panels on 0.4% of the certificates. Most common build period on the certificates: 1930-1949. Designated: 1 March 1990.
Compared with Brent and England
Share of homes
Barn Hill
All 23 areas in Brent
England
Solid walls, no insulation
49.4%
77.8%
48.7%
Gas boiler
99.0%
85.7%
66.4%
Rated D–G
79.7%
—
56.5%
Caveats
Certificates describe a home when it was assessed; 53% of these are from 2020 or later (latest 15 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 Brent if in doubt.
Boundary: London Borough of Brent via planning.data.gov.uk (entity 44014815, reference CA01, 40.5 ha); the council's appraisal or map. Homes are placed by the coordinates of their UPRN (OS Open UPRN); addresses are not shown.