Solar panels, heat pumps and insulation in Windmill Hill, Gravesend conservation area
In the Windmill Hill, Gravesend conservation area (Gravesham), 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 Gravesham covers this area 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 14 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. 391 homes inside the boundary have an energy certificate: 71.4% are solid-wall homes with no wall insulation, 78.5% heat with a gas boiler and 72.9% are rated D–G; 10 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
391homes with an energy certificate
71.4%solid walls, no insulation
78.5%heated by a gas boiler
10heat pumps
Article 4: An Article 4 direction published by Gravesham covers this area 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. (19 Clarence Place - Ar/76/2; 4, Clarence Place - Ar/97/1; 5, Clarence Place - Ar/82/1; Southern Water Windmill Hill Pumping Station Ar/07/1; Windmill Hill Pumping Station, Ar/07/2; Windmill Hill, CA North - Ar/98/1)
What needs planning permission in Windmill Hill, Gravesend
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
Planning permission needed (an Article 4 direction here removes this right)
Part 1 Class A, A.3(a)
Listed buildings: 14 in the area. 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: 43% 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 = 391)
Walls
Homes
Share
Solid wall (brick or stone), no insulation
279
71.4%
Cavity wall, unfilled
26
6.6%
Modern wall (U-value from the design)
19
4.9%
Solid wall, internal insulation
17
4.3%
Timber frame
12
3.1%
Cavity wall, filled
11
2.8%
Cavity wall, partly insulated
10
2.6%
Cavity wall, insulated (as built or unspecified)
9
2.3%
Other or not known
8
2.0%
Heating
Homes
Share
Gas boiler
307
78.5%
Electric (storage heaters, panels, boiler)
43
11.0%
Communal heating
29
7.4%
Heat pump
10
2.6%
LPG
1
0.3%
Oil
1
0.3%
Loft / roof insulation
Homes
Share
No insulation
88
22.5%
Under 200 mm
88
22.5%
200 mm or more
62
15.9%
Insulated (depth not recorded)
38
9.7%
Flat or other home above
102
26.1%
Other
13
3.3%
Windows
Homes
Share
Double glazed
298
76.2%
Single glazed
74
18.9%
Secondary glazing
19
4.9%
CDE
Energy rating: B 8 (2.0%) · C 98 (25.1%) · D 184 (47.1%) · E 90 (23.0%) · F 8 (2.0%) · G 3 (0.8%). Houses and bungalows: 57% of the homes; solar panels on 0.5% of the certificates. Most common build period on the certificates: before 1900. Designated: 18 August 1975.
Compared with Gravesham and England
Share of homes
Windmill Hill, Gravesend
All 23 areas in Gravesham
England
Solid walls, no insulation
71.4%
59.6%
48.7%
Gas boiler
78.5%
68.8%
66.4%
Rated D–G
72.9%
—
56.5%
Caveats
Certificates describe a home when it was assessed; 59% of these are from 2020 or later (latest 15 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 Gravesham if in doubt.
Boundary: Gravesham Borough Council via planning.data.gov.uk (entity 44016180, reference 2008/25/CONARA, 16.8 ha); the council's appraisal or map. Homes are placed by the coordinates of their UPRN (OS Open UPRN); addresses are not shown.