Solar panels, heat pumps and insulation in St Johns conservation area
In the St Johns conservation area (Lewisham), 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 Lewisham covers this area, but the published data does not say which rights it removes — check the direction before any work. The area has 4 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. 214 homes inside the boundary have an energy certificate: 64.0% are solid-wall homes with no wall insulation, 92.1% heat with a gas boiler and 50.5% are rated D–G; 0 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
214homes with an energy certificate
64.0%solid walls, no insulation
92.1%heated by a gas boiler
0heat pumps
Article 4: An Article 4 direction published by Lewisham covers this area, but the published data does not say which rights it removes — check the direction before any work. (Small HMO Northern Extension)
What needs planning permission in St Johns
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: 4 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: 65% 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 = 214)
Walls
Homes
Share
Solid wall (brick or stone), no insulation
137
64.0%
Cavity wall, insulated (as built or unspecified)
20
9.3%
Cavity wall, filled
17
7.9%
Cavity wall, unfilled
15
7.0%
Solid wall, internal insulation
10
4.7%
Cavity wall, partly insulated
5
2.3%
Modern wall (U-value from the design)
5
2.3%
Timber frame
4
1.9%
Solid wall, insulated
1
0.5%
Heating
Homes
Share
Gas boiler
197
92.1%
Electric (storage heaters, panels, boiler)
15
7.0%
Communal heating
1
0.5%
LPG
1
0.5%
Loft / roof insulation
Homes
Share
No insulation
31
14.5%
Under 200 mm
29
13.6%
200 mm or more
41
19.2%
Insulated (depth not recorded)
18
8.4%
Flat or other home above
90
42.1%
Other
5
2.3%
Windows
Homes
Share
Double glazed
165
77.1%
Single glazed
44
20.6%
Secondary glazing
5
2.3%
CD
Energy rating: B 4 (1.9%) · C 102 (47.7%) · D 85 (39.7%) · E 16 (7.5%) · F 3 (1.4%) · G 4 (1.9%). Houses and bungalows: 35% of the homes; solar panels on 0.5% of the certificates. Most common build period on the certificates: 1900-1929. Designated: 1 January 1976.
Compared with Lewisham and England
Share of homes
St Johns
All 31 areas in Lewisham
England
Solid walls, no insulation
64.0%
69.0%
48.7%
Gas boiler
92.1%
85.5%
66.4%
Rated D–G
50.5%
—
56.5%
Caveats
Certificates describe a home when it was assessed; 62% of these are from 2020 or later (latest 31 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 Lewisham if in doubt.
Boundary: London Borough of Lewisham via planning.data.gov.uk (entity 44014979, reference LEWCA15, 7.8 ha); the council's appraisal or map. Homes are placed by the coordinates of their UPRN (OS Open UPRN); addresses are not shown.