Solar panels, heat pumps and insulation in Porthleven conservation area
In the Porthleven conservation area (Cornwall), 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. The area has 28 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. 473 homes inside the boundary have an energy certificate: 59.4% are solid-wall homes with no wall insulation, 0.0% heat with a gas boiler and 83.9% are rated D–G; 40 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
473homes with an energy certificate
59.4%solid walls, no insulation
0.0%heated by a gas boiler
40heat pumps
Article 4: Cornwall does not publish Article 4 areas on planning.data.gov.uk — check with the council.
What needs planning permission in Porthleven
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), unless an Article 4 direction removes it — check with the council
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), unless an Article 4 direction removes it — check with the council
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)
Prior approval of appearance from the council, unless an Article 4 direction removes it — check with the council
Replacement windows and doors of similar appearance
No permission needed (permitted development), unless an Article 4 direction removes it — check with the council
Part 1 Class A, A.3(a)
Listed buildings: 28 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: 20% 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 = 473)
Walls
Homes
Share
Solid wall (brick or stone), no insulation
281
59.4%
Cavity wall, insulated (as built or unspecified)
62
13.1%
Cavity wall, filled
28
5.9%
Cavity wall, unfilled
27
5.7%
Solid wall, internal insulation
23
4.9%
Modern wall (U-value from the design)
20
4.2%
Timber frame
12
2.5%
Solid wall, insulated
6
1.3%
Cavity wall, partly insulated
5
1.1%
Solid wall, external insulation
5
1.1%
Cavity wall, internal or external insulation
4
0.8%
Heating
Homes
Share
Electric (storage heaters, panels, boiler)
263
55.6%
Oil
121
25.6%
Heat pump
40
8.5%
LPG
20
4.2%
Communal heating
15
3.2%
Solid fuel (wood, coal)
14
3.0%
Loft / roof insulation
Homes
Share
No insulation
54
11.4%
Under 200 mm
106
22.4%
200 mm or more
174
36.8%
Insulated (depth not recorded)
72
15.2%
Flat or other home above
48
10.1%
Other
19
4.0%
Windows
Homes
Share
Double glazed
439
92.8%
Single glazed
29
6.1%
Triple glazed
3
0.6%
Secondary glazing
2
0.4%
CDEF
Energy rating: A 3 (0.6%) · B 21 (4.4%) · C 52 (11.0%) · D 86 (18.2%) · E 195 (41.2%) · F 81 (17.1%) · G 35 (7.4%). Houses and bungalows: 80% of the homes; solar panels on 0.6% of the certificates. Most common build period on the certificates: before 1900. Designated: 28 February 1978.
Compared with Cornwall and England
Share of homes
Porthleven
All 145 areas in Cornwall
England
Solid walls, no insulation
59.4%
56.0%
48.7%
Gas boiler
0.0%
51.3%
66.4%
Rated D–G
83.9%
—
56.5%
Caveats
Certificates describe a home when it was assessed; 56% of these are from 2020 or later (latest 30 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 Cornwall if in doubt.
Boundary: Cornwall Council via planning.data.gov.uk (entity 44002632, reference DCO86, 31.1 ha); the council's appraisal or map. Homes are placed by the coordinates of their UPRN (OS Open UPRN); addresses are not shown.