Solar panels, heat pumps and insulation in Mildenhall conservation area
In the Mildenhall conservation area (West Suffolk), 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 47 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. 472 homes inside the boundary have an energy certificate: 32.4% are solid-wall homes with no wall insulation, 65.7% heat with a gas boiler and 50.4% 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
472homes with an energy certificate
32.4%solid walls, no insulation
65.7%heated by a gas boiler
1heat pumps
Article 4: West Suffolk does not publish Article 4 areas on planning.data.gov.uk — check with the council.
What needs planning permission in Mildenhall
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: 47 in the area (grade I: 1, II*: 0). 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: 56% 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 = 472)
Walls
Homes
Share
Cavity wall, insulated (as built or unspecified)
185
39.2%
Solid wall (brick or stone), no insulation
153
32.4%
Modern wall (U-value from the design)
37
7.8%
Cavity wall, filled
34
7.2%
Timber frame
21
4.4%
Cavity wall, unfilled
16
3.4%
Solid wall, insulated
11
2.3%
Solid wall, internal insulation
10
2.1%
Cavity wall, partly insulated
2
0.4%
Other or not known
2
0.4%
Cavity wall, internal or external insulation
1
0.2%
Heating
Homes
Share
Gas boiler
310
65.7%
Electric (storage heaters, panels, boiler)
154
32.6%
Oil
6
1.3%
Communal heating
1
0.2%
Heat pump
1
0.2%
Loft / roof insulation
Homes
Share
No insulation
25
5.3%
Under 200 mm
63
13.3%
200 mm or more
162
34.3%
Insulated (depth not recorded)
65
13.8%
Flat or other home above
134
28.4%
Other
23
4.9%
Windows
Homes
Share
Double glazed
379
80.3%
Single glazed
52
11.0%
Secondary glazing
38
8.1%
Triple glazed
3
0.6%
BCDE
Energy rating: A 1 (0.2%) · B 48 (10.2%) · C 185 (39.2%) · D 163 (34.5%) · E 62 (13.1%) · F 8 (1.7%) · G 5 (1.1%). Houses and bungalows: 44% of the homes; solar panels on 0.2% of the certificates. Most common build period on the certificates: before 1900. Designated: 19 October 1973.
Compared with West Suffolk and England
Share of homes
Mildenhall
All 48 areas in West Suffolk
England
Solid walls, no insulation
32.4%
40.1%
48.7%
Gas boiler
65.7%
57.5%
66.4%
Rated D–G
50.4%
—
56.5%
Caveats
Certificates describe a home when it was assessed; 54% of these are from 2020 or later (latest 16 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 West Suffolk if in doubt.
Boundary: West Suffolk Council via planning.data.gov.uk (entity 44006977, reference 8600, 34.5 ha); the council's appraisal or map. Homes are placed by the coordinates of their UPRN (OS Open UPRN); addresses are not shown.