Solar panels, heat pumps and insulation in Tonbridge conservation area
In the Tonbridge conservation area (Tonbridge and Malling), 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 88 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. 1,153 homes inside the boundary have an energy certificate: 29.6% are solid-wall homes with no wall insulation, 72.8% heat with a gas boiler and 39.5% are rated D–G; 16 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
1,153homes with an energy certificate
29.6%solid walls, no insulation
72.8%heated by a gas boiler
16heat pumps
Article 4: Tonbridge and Malling does not publish Article 4 areas on planning.data.gov.uk — check with the council.
What needs planning permission in Tonbridge
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: 88 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: 64% 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 = 1,153)
Walls
Homes
Share
Solid wall (brick or stone), no insulation
341
29.6%
Cavity wall, insulated (as built or unspecified)
298
25.8%
Modern wall (U-value from the design)
262
22.7%
Timber frame
56
4.9%
Cavity wall, filled
54
4.7%
Cavity wall, unfilled
44
3.8%
Solid wall, internal insulation
28
2.4%
Solid wall, insulated
25
2.2%
Other or not known
17
1.5%
Cavity wall, internal or external insulation
16
1.4%
Cavity wall, partly insulated
9
0.8%
Solid wall, partly insulated
3
0.3%
Heating
Homes
Share
Gas boiler
839
72.8%
Electric (storage heaters, panels, boiler)
260
22.5%
Communal heating
36
3.1%
Heat pump
16
1.4%
Oil
1
0.1%
Solid fuel (wood, coal)
1
0.1%
Loft / roof insulation
Homes
Share
No insulation
105
9.1%
Under 200 mm
185
16.1%
200 mm or more
173
15.0%
Insulated (depth not recorded)
142
12.3%
Flat or other home above
407
35.3%
Other
140
12.2%
Windows
Homes
Share
Double glazed
1,018
88.3%
Single glazed
89
7.7%
Secondary glazing
43
3.7%
Triple glazed
3
0.3%
BCDE
Energy rating: B 202 (17.5%) · C 496 (43.0%) · D 289 (25.1%) · E 146 (12.7%) · F 14 (1.2%) · G 6 (0.5%). Houses and bungalows: 36% of the homes; solar panels on 0.3% of the certificates. Most common build period on the certificates: before 1900. Designated: 1 January 1969.
Compared with Tonbridge and Malling and England
Share of homes
Tonbridge
All 60 areas in Tonbridge and Malling
England
Solid walls, no insulation
29.6%
44.5%
48.7%
Gas boiler
72.8%
73.0%
66.4%
Rated D–G
39.5%
—
56.5%
Caveats
Certificates describe a home when it was assessed; 54% of these are from 2020 or later (latest 28 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 Tonbridge and Malling if in doubt.
Boundary: Tonbridge and Malling Borough Council via planning.data.gov.uk (entity 44004176, reference 2362, 68.7 ha); the council's appraisal or map. Homes are placed by the coordinates of their UPRN (OS Open UPRN); addresses are not shown.