Solar panels, heat pumps and insulation in Cornwall conservation area
In the Cornwall conservation area (Kensington and Chelsea), 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 Kensington and Chelsea covers this area but deals with other things (such as changes of use); it does not change the rules below. The area has 11 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. 966 homes inside the boundary have an energy certificate: 86.2% are solid-wall homes with no wall insulation, 71.9% heat with a gas boiler and 50.1% are rated D–G; 8 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
966homes with an energy certificate
86.2%solid walls, no insulation
71.9%heated by a gas boiler
8heat pumps
Article 4: An Article 4 direction published by Kensington and Chelsea covers this area but deals with other things (such as changes of use); it does not change the rules below. (Article 4 - No 100; Article 4 - No 106)
What needs planning permission in Cornwall
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: 11 in the area (grade I: 0, II*: 1). 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: 95% 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 = 966)
Walls
Homes
Share
Solid wall (brick or stone), no insulation
833
86.2%
Solid wall, internal insulation
45
4.7%
Modern wall (U-value from the design)
39
4.0%
Timber frame
25
2.6%
Cavity wall, insulated (as built or unspecified)
7
0.7%
Other or not known
7
0.7%
Solid wall, insulated
4
0.4%
Solid wall, partly insulated
4
0.4%
Cavity wall, partly insulated
1
0.1%
Cavity wall, unfilled
1
0.1%
Heating
Homes
Share
Gas boiler
695
71.9%
Electric (storage heaters, panels, boiler)
143
14.8%
Communal heating
118
12.2%
Heat pump
8
0.8%
LPG
2
0.2%
Loft / roof insulation
Homes
Share
No insulation
134
13.9%
Under 200 mm
16
1.7%
200 mm or more
2
0.2%
Insulated (depth not recorded)
56
5.8%
Flat or other home above
741
76.8%
Other
16
1.7%
Windows
Homes
Share
Single glazed
526
54.5%
Double glazed
394
40.8%
Secondary glazing
45
4.7%
Triple glazed
1
0.1%
CDE
Energy rating: B 38 (3.9%) · C 444 (46.0%) · D 362 (37.5%) · E 103 (10.7%) · F 13 (1.3%) · G 6 (0.6%). Houses and bungalows: 5% of the homes; solar panels on 0.0% of the certificates. Most common build period on the certificates: before 1900. Designated: 1 January 1969.
Compared with Kensington and Chelsea and England
Share of homes
Cornwall
All 44 areas in Kensington and Chelsea
England
Solid walls, no insulation
86.2%
79.7%
48.7%
Gas boiler
71.9%
72.9%
66.4%
Rated D–G
50.1%
—
56.5%
Caveats
Certificates describe a home when it was assessed; 55% of these are from 2020 or later (latest 1 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 Kensington and Chelsea if in doubt.
Boundary: Royal Borough of Kensington and Chelsea via planning.data.gov.uk (entity 44012770, reference 12, 7.8 ha); the council's appraisal or map. Homes are placed by the coordinates of their UPRN (OS Open UPRN); addresses are not shown.