Solar panels, heat pumps and insulation in Mill Road conservation area
In the Mill Road conservation area (Worthing), 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. 59 homes inside the boundary have an energy certificate: 46% are solid-wall homes with no wall insulation, 83% heat with a gas boiler and 49% 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
59homes with an energy certificate
46%solid walls, no insulation
83%heated by a gas boiler
0heat pumps
Article 4: Worthing 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 Mill Road
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: none recorded inside the boundary; on a listed building, solar panels and heat pumps are not permitted development and need listed building consent.
Flats: 71% 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 = 59)
Walls
Homes
Share
Solid wall (brick or stone), no insulation
27
46%
Cavity wall, insulated (as built or unspecified)
11
19%
Cavity wall, unfilled
8
14%
Modern wall (U-value from the design)
5
8%
Timber frame
3
5%
Cavity wall, filled
1
2%
Cavity wall, internal or external insulation
1
2%
Cavity wall, partly insulated
1
2%
Solid wall, internal insulation
1
2%
Solid wall, partly insulated
1
2%
Heating
Homes
Share
Gas boiler
49
83%
Communal heating
6
10%
Electric (storage heaters, panels, boiler)
4
7%
Loft / roof insulation
Homes
Share
No insulation
4
7%
Under 200 mm
10
17%
200 mm or more
11
19%
Insulated (depth not recorded)
8
14%
Flat or other home above
21
36%
Other
5
8%
Windows
Homes
Share
Double glazed
45
76%
Single glazed
11
19%
Secondary glazing
3
5%
BCDE
Energy rating: B 6 (10%) · C 24 (41%) · D 17 (29%) · E 8 (14%) · F 4 (7%). Houses and bungalows: 29% of the homes; solar panels on 0% of the certificates. Most common build period on the certificates: 1900-1929. Designated: 29 April 2000.
Compared with Worthing and England
Share of homes
Mill Road
All 26 areas in Worthing
England
Solid walls, no insulation
46%
49.8%
48.7%
Gas boiler
83%
61.5%
66.4%
Rated D–G
49%
—
56.5%
Caveats
Certificates describe a home when it was assessed; 42% of these are from 2020 or later (latest 24 December 2025). “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 Worthing if in doubt.
Boundary: Worthing Borough Council via planning.data.gov.uk (entity 44014017, reference WCA15, 2.8 ha); the council's appraisal or map. Homes are placed by the coordinates of their UPRN (OS Open UPRN); addresses are not shown.