Solar panels, heat pumps and insulation in Horncastle conservation area
In the Horncastle conservation area (East Lindsey), 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 114 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. 528 homes inside the boundary have an energy certificate: 55.9% are solid-wall homes with no wall insulation, 75.2% heat with a gas boiler and 65.9% are rated D–G; 5 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
528homes with an energy certificate
55.9%solid walls, no insulation
75.2%heated by a gas boiler
5heat pumps
Article 4: East Lindsey does not publish Article 4 areas on planning.data.gov.uk — check with the council.
What needs planning permission in Horncastle
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: 114 in the area (grade I: 6, II*: 2). 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: 32% 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 = 528)
Walls
Homes
Share
Solid wall (brick or stone), no insulation
295
55.9%
Cavity wall, insulated (as built or unspecified)
85
16.1%
Modern wall (U-value from the design)
54
10.2%
Solid wall, internal insulation
40
7.6%
Cavity wall, filled
24
4.5%
Solid wall, insulated
12
2.3%
Cavity wall, unfilled
10
1.9%
Cavity wall, partly insulated
2
0.4%
Other or not known
2
0.4%
Timber frame
2
0.4%
Cavity wall, internal or external insulation
1
0.2%
Solid wall, external insulation
1
0.2%
Heating
Homes
Share
Gas boiler
397
75.2%
Electric (storage heaters, panels, boiler)
112
21.2%
Communal heating
7
1.3%
Heat pump
5
0.9%
Oil
3
0.6%
Solid fuel (wood, coal)
3
0.6%
LPG
1
0.2%
Loft / roof insulation
Homes
Share
No insulation
36
6.8%
Under 200 mm
142
26.9%
200 mm or more
211
40.0%
Insulated (depth not recorded)
36
6.8%
Flat or other home above
53
10.0%
Other
50
9.5%
Windows
Homes
Share
Double glazed
377
71.4%
Single glazed
116
22.0%
Secondary glazing
31
5.9%
Triple glazed
4
0.8%
CDE
Energy rating: A 1 (0.2%) · B 26 (4.9%) · C 153 (29.0%) · D 216 (40.9%) · E 112 (21.2%) · F 18 (3.4%) · G 2 (0.4%). Houses and bungalows: 68% of the homes; solar panels on 0.9% of the certificates. Most common build period on the certificates: before 1900.
Compared with East Lindsey and England
Share of homes
Horncastle
All 17 areas in East Lindsey
England
Solid walls, no insulation
55.9%
56.7%
48.7%
Gas boiler
75.2%
68.9%
66.4%
Rated D–G
65.9%
—
56.5%
Caveats
Certificates describe a home when it was assessed; 56% 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 East Lindsey if in doubt.
Boundary: East Lindsey District Council via planning.data.gov.uk (entity 44001186, reference 4522, 37.8 ha); the council's appraisal or map. Homes are placed by the coordinates of their UPRN (OS Open UPRN); addresses are not shown.