Solar panels, heat pumps and insulation in Westbury conservation area
In the Westbury 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. The area has 95 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. 667 homes inside the boundary have an energy certificate: 38.4% are solid-wall homes with no wall insulation, 61.5% heat with a gas boiler and 51.6% are rated D–G; 2 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
667homes with an energy certificate
38.4%solid walls, no insulation
61.5%heated by a gas boiler
2heat pumps
Article 4: Wiltshire publishes its Article 4 areas on planning.data.gov.uk and none overlaps this area; a direction can still exist on paper, so check with the council.
What needs planning permission in Westbury
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: 95 in the area (grade I: 1, II*: 4). 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: 43% 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 = 667)
Walls
Homes
Share
Solid wall (brick or stone), no insulation
256
38.4%
Cavity wall, insulated (as built or unspecified)
242
36.3%
Cavity wall, unfilled
33
4.9%
Modern wall (U-value from the design)
33
4.9%
Solid wall, insulated
26
3.9%
Solid wall, internal insulation
24
3.6%
Cavity wall, filled
22
3.3%
Timber frame
20
3.0%
Cavity wall, partly insulated
7
1.0%
Other or not known
2
0.3%
Solid wall, partly insulated
2
0.3%
Heating
Homes
Share
Gas boiler
410
61.5%
Electric (storage heaters, panels, boiler)
183
27.4%
Communal heating
68
10.2%
Oil
4
0.6%
Heat pump
2
0.3%
Loft / roof insulation
Homes
Share
No insulation
63
9.4%
Under 200 mm
126
18.9%
200 mm or more
182
27.3%
Insulated (depth not recorded)
123
18.4%
Flat or other home above
144
21.6%
Other
29
4.3%
Windows
Homes
Share
Double glazed
579
86.8%
Single glazed
69
10.3%
Secondary glazing
19
2.8%
BCDE
Energy rating: B 73 (10.9%) · C 250 (37.5%) · D 216 (32.4%) · E 115 (17.2%) · F 11 (1.6%) · G 2 (0.3%). Houses and bungalows: 57% of the homes; solar panels on 0.0% of the certificates. Most common build period on the certificates: before 1900. Designated: 1 January 1975.
Compared with Wiltshire and England
Share of homes
Westbury
All 244 areas in Wiltshire
England
Solid walls, no insulation
38.4%
42.5%
48.7%
Gas boiler
61.5%
45.5%
66.4%
Rated D–G
51.6%
—
56.5%
Caveats
Certificates describe a home when it was assessed; 49% of these are from 2020 or later (latest 22 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 44015329, reference CA/W/220, 21.8 ha); the council's appraisal or map. Homes are placed by the coordinates of their UPRN (OS Open UPRN); addresses are not shown.