Solar panels, heat pumps and insulation in Trowbridge (newtown) conservation area
In the Trowbridge (newtown) 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 17 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. 630 homes inside the boundary have an energy certificate: 85.9% are solid-wall homes with no wall insulation, 86.5% heat with a gas boiler and 82.2% 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
630homes with an energy certificate
85.9%solid walls, no insulation
86.5%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 Trowbridge (newtown)
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: 17 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 = 630)
Walls
Homes
Share
Solid wall (brick or stone), no insulation
541
85.9%
Cavity wall, unfilled
22
3.5%
Modern wall (U-value from the design)
16
2.5%
Solid wall, internal insulation
13
2.1%
Cavity wall, insulated (as built or unspecified)
12
1.9%
Cavity wall, filled
10
1.6%
Timber frame
5
0.8%
Solid wall, insulated
4
0.6%
Cavity wall, partly insulated
3
0.5%
Cavity wall, internal or external insulation
2
0.3%
Solid wall, external insulation
2
0.3%
Heating
Homes
Share
Gas boiler
545
86.5%
Electric (storage heaters, panels, boiler)
67
10.6%
Communal heating
15
2.4%
Heat pump
2
0.3%
Solid fuel (wood, coal)
1
0.2%
Loft / roof insulation
Homes
Share
No insulation
124
19.7%
Under 200 mm
217
34.4%
200 mm or more
175
27.8%
Insulated (depth not recorded)
42
6.7%
Flat or other home above
57
9.0%
Other
15
2.4%
Windows
Homes
Share
Double glazed
609
96.7%
Single glazed
17
2.7%
Secondary glazing
3
0.5%
Triple glazed
1
0.2%
CDE
Energy rating: A 1 (0.2%) · B 9 (1.4%) · C 102 (16.2%) · D 324 (51.4%) · E 168 (26.7%) · F 17 (2.7%) · G 9 (1.4%). Houses and bungalows: 80% of the homes; solar panels on 1.3% of the certificates. Most common build period on the certificates: before 1900. Designated: 1 January 1975.
Compared with Wiltshire and England
Share of homes
Trowbridge (newtown)
All 244 areas in Wiltshire
England
Solid walls, no insulation
85.9%
42.5%
48.7%
Gas boiler
86.5%
45.5%
66.4%
Rated D–G
82.2%
—
56.5%
Caveats
Certificates describe a home when it was assessed; 51% of these are from 2020 or later (latest 25 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 44015322, reference CA/W/204, 25.2 ha); the council's appraisal or map. Homes are placed by the coordinates of their UPRN (OS Open UPRN); addresses are not shown.