Solar panels, heat pumps and insulation in The Greenway conservation area
In the The Greenway 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. 437 homes inside the boundary have an energy certificate: 54.5% are solid-wall homes with no wall insulation, 92.9% heat with a gas boiler and 62.5% 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
437homes with an energy certificate
54.5%solid walls, no insulation
92.9%heated by a gas boiler
1heat 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. (Houses of Multiple Occupation (HMOs); Residential extensions)
What needs planning permission in The Greenway
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: none recorded inside the boundary; on a listed building, solar panels and heat pumps are not permitted development and need listed building consent.
Flats: 49% 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 = 437)
Walls
Homes
Share
Solid wall (brick or stone), no insulation
238
54.5%
Cavity wall, insulated (as built or unspecified)
57
13.0%
Cavity wall, unfilled
51
11.7%
Cavity wall, filled
34
7.8%
Cavity wall, partly insulated
19
4.3%
Modern wall (U-value from the design)
15
3.4%
Timber frame
10
2.3%
Solid wall, internal insulation
7
1.6%
Other or not known
3
0.7%
Solid wall, insulated
3
0.7%
Heating
Homes
Share
Gas boiler
406
92.9%
Electric (storage heaters, panels, boiler)
30
6.9%
Heat pump
1
0.2%
Loft / roof insulation
Homes
Share
No insulation
74
16.9%
Under 200 mm
121
27.7%
200 mm or more
65
14.9%
Insulated (depth not recorded)
53
12.1%
Flat or other home above
108
24.7%
Other
16
3.7%
Windows
Homes
Share
Double glazed
400
91.5%
Single glazed
31
7.1%
Other
3
0.7%
Secondary glazing
2
0.5%
Triple glazed
1
0.2%
CDE
Energy rating: B 10 (2.3%) · C 154 (35.2%) · D 201 (46.0%) · E 61 (14.0%) · F 11 (2.5%). Houses and bungalows: 51% of the homes; solar panels on 0.2% of the certificates. Most common build period on the certificates: 1900-1929. Designated: 16 October 1975.
Compared with Hillingdon and England
Share of homes
The Greenway
All 32 areas in Hillingdon
England
Solid walls, no insulation
54.5%
25.5%
48.7%
Gas boiler
92.9%
62.7%
66.4%
Rated D–G
62.5%
—
56.5%
Caveats
Certificates describe a home when it was assessed; 57% of these are from 2020 or later (latest 9 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 44015530, reference CA-6, 16.4 ha); the council's appraisal or map. Homes are placed by the coordinates of their UPRN (OS Open UPRN); addresses are not shown.