Solar panels, heat pumps and insulation in Steyning conservation area
In the Steyning conservation area (Horsham), 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 111 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. 331 homes inside the boundary have an energy certificate: 55.9% are solid-wall homes with no wall insulation, 85.8% heat with a gas boiler and 74.9% are rated D–G; 1 has 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
331homes with an energy certificate
55.9%solid walls, no insulation
85.8%heated by a gas boiler
1heat pumps
Article 4: Horsham 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 Steyning
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: 111 in the area (grade I: 2, II*: 7). 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: 19% 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 = 331)
Walls
Homes
Share
Solid wall (brick or stone), no insulation
185
55.9%
Cavity wall, insulated (as built or unspecified)
47
14.2%
Cavity wall, unfilled
26
7.9%
Modern wall (U-value from the design)
22
6.6%
Cavity wall, filled
21
6.3%
Timber frame
10
3.0%
Solid wall, internal insulation
8
2.4%
Solid wall, insulated
7
2.1%
Cavity wall, partly insulated
4
1.2%
Solid wall, partly insulated
1
0.3%
Heating
Homes
Share
Gas boiler
284
85.8%
Electric (storage heaters, panels, boiler)
44
13.3%
Communal heating
1
0.3%
Heat pump
1
0.3%
Solid fuel (wood, coal)
1
0.3%
Loft / roof insulation
Homes
Share
No insulation
63
19.1%
Under 200 mm
111
33.6%
200 mm or more
62
18.8%
Insulated (depth not recorded)
53
16.1%
Flat or other home above
18
5.5%
Other
23
7.0%
Windows
Homes
Share
Double glazed
263
79.5%
Single glazed
57
17.2%
Secondary glazing
11
3.3%
CDE
Energy rating: B 7 (2.1%) · C 76 (23.0%) · D 147 (44.4%) · E 86 (26.0%) · F 10 (3.0%) · G 5 (1.5%). Houses and bungalows: 81% of the homes; solar panels on 0.0% of the certificates. Most common build period on the certificates: before 1900. Designated: 25 January 2018.
Compared with Horsham and England
Share of homes
Steyning
All 40 areas in Horsham
England
Solid walls, no insulation
55.9%
32.5%
48.7%
Gas boiler
85.8%
67.6%
66.4%
Rated D–G
74.9%
—
56.5%
Caveats
Certificates describe a home when it was assessed; 51% 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 Horsham if in doubt.
Boundary: Horsham District Council via planning.data.gov.uk (entity 44003590, reference CONARAST001, 32.0 ha); the council's appraisal or map. Homes are placed by the coordinates of their UPRN (OS Open UPRN); addresses are not shown.