Solar panels, heat pumps and insulation in St Albans - Holywell Hill / Sopwell Lane conservation area
In the St Albans - Holywell Hill / Sopwell Lane conservation area (St Albans), 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 St Albans covers part of this area (about 18% of it) and removes permitted development rights for replacement windows and doors, and other alterations to the house, alterations to the roof (e.g. rooflights), chimneys, flues and soil pipes, painting the outside, so there these need planning permission too. The area has 49 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. 604 homes inside the boundary have an energy certificate: 51.5% are solid-wall homes with no wall insulation, 86.6% heat with a gas boiler and 60.8% 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
604homes with an energy certificate
51.5%solid walls, no insulation
86.6%heated by a gas boiler
0heat pumps
Article 4: An Article 4 direction published by St Albans covers part of this area (about 18% of it) and removes permitted development rights for replacement windows and doors, and other alterations to the house, alterations to the roof (e.g. rooflights), chimneys, flues and soil pipes, painting the outside, so there these need planning permission too. (Sopwell Lane and Albert Street)
What needs planning permission in St Albans - Holywell Hill / Sopwell Lane
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
Inside the Article 4 part of the area: planning permission needed; elsewhere: no permission needed (permitted development)
Part 1 Class A, A.3(a)
Listed buildings: 49 in the area (grade I: 0, 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: 38% 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 = 604)
Walls
Homes
Share
Solid wall (brick or stone), no insulation
311
51.5%
Cavity wall, insulated (as built or unspecified)
168
27.8%
Cavity wall, filled
50
8.3%
Cavity wall, unfilled
22
3.6%
Timber frame
20
3.3%
Solid wall, internal insulation
13
2.2%
Cavity wall, partly insulated
6
1.0%
Modern wall (U-value from the design)
6
1.0%
Other or not known
6
1.0%
Solid wall, external insulation
2
0.3%
Heating
Homes
Share
Gas boiler
523
86.6%
Electric (storage heaters, panels, boiler)
79
13.1%
Communal heating
1
0.2%
LPG
1
0.2%
Loft / roof insulation
Homes
Share
No insulation
107
17.7%
Under 200 mm
183
30.3%
200 mm or more
113
18.7%
Insulated (depth not recorded)
66
10.9%
Flat or other home above
129
21.4%
Other
6
1.0%
Windows
Homes
Share
Double glazed
506
83.8%
Single glazed
70
11.6%
Secondary glazing
26
4.3%
Triple glazed
2
0.3%
CDE
Energy rating: B 15 (2.5%) · C 222 (36.8%) · D 279 (46.2%) · E 77 (12.7%) · F 8 (1.3%) · G 3 (0.5%). Houses and bungalows: 62% of the homes; solar panels on 0.5% of the certificates. Most common build period on the certificates: 1900-1929. Designated: 24 March 1969.
Compared with St Albans and England
Share of homes
St Albans - Holywell Hill / Sopwell Lane
All 45 areas in St Albans
England
Solid walls, no insulation
51.5%
37.1%
48.7%
Gas boiler
86.6%
76.8%
66.4%
Rated D–G
60.8%
—
56.5%
Caveats
Certificates describe a home when it was assessed; 56% of these are from 2020 or later (latest 8 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 St Albans if in doubt.
Boundary: St Albans City and District Council via planning.data.gov.uk (entity 44010118, reference CA11_4d, 18.3 ha); the council's appraisal or map. Homes are placed by the coordinates of their UPRN (OS Open UPRN); addresses are not shown.