Solar panels, heat pumps and insulation in Diss (12/00102/CONARA) conservation area
In the Diss conservation area (South Norfolk), 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 South Norfolk covers part of this area (about 0% of it), but the published data does not say which rights it removes — check the direction before any work. The area has 149 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. 527 homes inside the boundary have an energy certificate: 27.3% are solid-wall homes with no wall insulation, 65.3% heat with a gas boiler and 56.5% are rated D–G; 11 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
527homes with an energy certificate
27.3%solid walls, no insulation
65.3%heated by a gas boiler
11heat pumps
Article 4: An Article 4 direction published by South Norfolk covers part of this area (about 0% of it), but the published data does not say which rights it removes — check the direction before any work. (Riverside)
What needs planning permission in Diss
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: 149 in the area (grade I: 1, 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: 45% 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 = 527)
Walls
Homes
Share
Solid wall (brick or stone), no insulation
144
27.3%
Cavity wall, insulated (as built or unspecified)
130
24.7%
Cavity wall, filled
95
18.0%
Timber frame
52
9.9%
Modern wall (U-value from the design)
40
7.6%
Cavity wall, unfilled
29
5.5%
Solid wall, internal insulation
17
3.2%
Solid wall, insulated
11
2.1%
Cavity wall, partly insulated
6
1.1%
Cavity wall, internal or external insulation
1
0.2%
Solid wall, external insulation
1
0.2%
Solid wall, partly insulated
1
0.2%
Heating
Homes
Share
Gas boiler
344
65.3%
Electric (storage heaters, panels, boiler)
116
22.0%
Communal heating
52
9.9%
Heat pump
11
2.1%
Oil
3
0.6%
LPG
1
0.2%
Loft / roof insulation
Homes
Share
No insulation
49
9.3%
Under 200 mm
100
19.0%
200 mm or more
185
35.2%
Insulated (depth not recorded)
60
11.4%
Flat or other home above
98
18.6%
Other
34
6.5%
Windows
Homes
Share
Double glazed
442
83.9%
Single glazed
51
9.7%
Secondary glazing
32
6.1%
Triple glazed
2
0.4%
CDE
Energy rating: A 1 (0.2%) · B 22 (4.2%) · C 206 (39.1%) · D 179 (34.0%) · E 91 (17.3%) · F 14 (2.7%) · G 14 (2.7%). Houses and bungalows: 55% of the homes; solar panels on 0.4% of the certificates. Most common build period on the certificates: before 1900. Designated: 1 January 1974.
Compared with South Norfolk and England
Share of homes
Diss
All 84 areas in South Norfolk
England
Solid walls, no insulation
27.3%
41.0%
48.7%
Gas boiler
65.3%
47.8%
66.4%
Rated D–G
56.5%
—
56.5%
Caveats
Certificates describe a home when it was assessed; 50% of these are from 2020 or later (latest 22 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 South Norfolk if in doubt.
Boundary: South Norfolk District Council via planning.data.gov.uk (entity 44013402, reference 12/00102/CONARA, 54.9 ha); the council's appraisal or map. Homes are placed by the coordinates of their UPRN (OS Open UPRN); addresses are not shown.