Solar panels, heat pumps and insulation in Malmesbury conservation area
In the Malmesbury conservation area (Wiltshire), 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 Wiltshire covers part of this area (about 6% of it) and removes permitted development rights for replacement windows and doors, and other alterations to the house, alterations to the roof (e.g. rooflights), painting the outside, so there these need planning permission too. The area has 315 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. 670 homes inside the boundary have an energy certificate: 60.9% are solid-wall homes with no wall insulation, 80.4% heat with a gas boiler and 69.4% are rated D–G; 3 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
670homes with an energy certificate
60.9%solid walls, no insulation
80.4%heated by a gas boiler
3heat pumps
Article 4: An Article 4 direction published by Wiltshire covers part of this area (about 6% of it) and removes permitted development rights for replacement windows and doors, and other alterations to the house, alterations to the roof (e.g. rooflights), painting the outside, so there these need planning permission too. (Malmesbury)
What needs planning permission in Malmesbury
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
Inside the Article 4 part of the area: planning permission needed; elsewhere: no permission needed (permitted development)
Part 1 Class A, A.3(a)
Listed buildings: 315 in the area (grade I: 6, II*: 14). 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: 31% 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 = 670)
Walls
Homes
Share
Solid wall (brick or stone), no insulation
408
60.9%
Cavity wall, insulated (as built or unspecified)
76
11.3%
Cavity wall, filled
62
9.3%
Modern wall (U-value from the design)
40
6.0%
Cavity wall, unfilled
21
3.1%
Solid wall, insulated
18
2.7%
Cavity wall, partly insulated
17
2.5%
Solid wall, internal insulation
16
2.4%
Timber frame
7
1.0%
Solid wall, partly insulated
4
0.6%
Other or not known
1
0.1%
Heating
Homes
Share
Gas boiler
539
80.4%
Communal heating
68
10.1%
Electric (storage heaters, panels, boiler)
49
7.3%
Oil
7
1.0%
Heat pump
3
0.4%
Solid fuel (wood, coal)
3
0.4%
LPG
1
0.1%
Loft / roof insulation
Homes
Share
No insulation
165
24.6%
Under 200 mm
122
18.2%
200 mm or more
119
17.8%
Insulated (depth not recorded)
147
21.9%
Flat or other home above
88
13.1%
Other
29
4.3%
Windows
Homes
Share
Double glazed
502
74.9%
Single glazed
119
17.8%
Secondary glazing
48
7.2%
Triple glazed
1
0.1%
CDE
Energy rating: B 20 (3.0%) · C 185 (27.6%) · D 275 (41.0%) · E 156 (23.3%) · F 24 (3.6%) · G 10 (1.5%). Houses and bungalows: 69% of the homes; solar panels on 0.6% of the certificates. Most common build period on the certificates: before 1900.
Compared with Wiltshire and England
Share of homes
Malmesbury
All 244 areas in Wiltshire
England
Solid walls, no insulation
60.9%
42.5%
48.7%
Gas boiler
80.4%
45.5%
66.4%
Rated D–G
69.4%
—
56.5%
Caveats
Certificates describe a home when it was assessed; 50% of these are from 2020 or later (latest 19 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 Wiltshire if in doubt.
Boundary: Wiltshire Council via planning.data.gov.uk (entity 44015196, reference CA/N/139, 76.8 ha); the council's appraisal or map. Homes are placed by the coordinates of their UPRN (OS Open UPRN); addresses are not shown.