Solar panels, heat pumps and insulation in Wellesley Road conservation area
In the Wellesley Road conservation area (Hounslow), 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 Hounslow covers this area but deals with other things (such as changes of use); it does not change the rules below. 1,191 homes inside the boundary have an energy certificate: 75.4% are solid-wall homes with no wall insulation, 90.5% heat with a gas boiler and 64.7% are rated D–G; 4 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
1,191homes with an energy certificate
75.4%solid walls, no insulation
90.5%heated by a gas boiler
4heat pumps
Article 4: An Article 4 direction published by Hounslow covers this area but deals with other things (such as changes of use); it does not change the rules below. (Dwellinghouses (C3) to small HMOs (C4) - borough-wide Article 4 Direction)
What needs planning permission in Wellesley Road
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
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: 74% 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 = 1,191)
Walls
Homes
Share
Solid wall (brick or stone), no insulation
898
75.4%
Cavity wall, unfilled
69
5.8%
Cavity wall, insulated (as built or unspecified)
55
4.6%
Cavity wall, filled
48
4.0%
Timber frame
35
2.9%
Cavity wall, partly insulated
26
2.2%
Modern wall (U-value from the design)
26
2.2%
Solid wall, insulated
11
0.9%
Solid wall, internal insulation
11
0.9%
Solid wall, partly insulated
7
0.6%
Other or not known
5
0.4%
Heating
Homes
Share
Gas boiler
1,078
90.5%
Communal heating
56
4.7%
Electric (storage heaters, panels, boiler)
52
4.4%
Heat pump
4
0.3%
LPG
1
0.1%
Loft / roof insulation
Homes
Share
No insulation
227
19.1%
Under 200 mm
136
11.4%
200 mm or more
65
5.5%
Insulated (depth not recorded)
172
14.5%
Flat or other home above
568
47.7%
Other
22
1.8%
Windows
Homes
Share
Double glazed
964
80.9%
Single glazed
196
16.5%
Secondary glazing
29
2.4%
Triple glazed
2
0.2%
CDE
Energy rating: B 31 (2.6%) · C 389 (32.7%) · D 578 (48.5%) · E 158 (13.3%) · F 31 (2.6%) · G 4 (0.3%). Houses and bungalows: 26% of the homes; solar panels on 0.1% of the certificates. Most common build period on the certificates: 1900-1929. Designated: 3 December 2002.
Compared with Hounslow and England
Share of homes
Wellesley Road
All 29 areas in Hounslow
England
Solid walls, no insulation
75.4%
49.9%
48.7%
Gas boiler
90.5%
77.4%
66.4%
Rated D–G
64.7%
—
56.5%
Caveats
Certificates describe a home when it was assessed; 50% of these are from 2020 or later (latest 31 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 Hounslow if in doubt.
Boundary: London Borough of Hounslow via planning.data.gov.uk (entity 44009065, reference 1232, 33.1 ha). Homes are placed by the coordinates of their UPRN (OS Open UPRN); addresses are not shown.