Solar panels, heat pumps and insulation in The Watling Estate conservation area
In the The Watling Estate conservation area (Barnet), 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 Barnet covers this area but deals with other things (such as changes of use); it does not change the rules below. The area has 2 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. 3,635 homes inside the boundary have an energy certificate: 30.2% are solid-wall homes with no wall insulation, 95.2% heat with a gas boiler and 63.6% are rated D–G; 2 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
3,635homes with an energy certificate
30.2%solid walls, no insulation
95.2%heated by a gas boiler
2heat pumps
Article 4: An Article 4 direction published by Barnet covers this area but deals with other things (such as changes of use); it does not change the rules below. (Article 4 Small Houses in Multiple Occupation (HMO) Area 1)
What needs planning permission in The Watling Estate
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: 2 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: 23% 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 = 3,635)
Walls
Homes
Share
Solid wall (brick or stone), no insulation
1,098
30.2%
Cavity wall, unfilled
951
26.2%
Cavity wall, filled
706
19.4%
Other or not known
320
8.8%
Timber frame
309
8.5%
Cavity wall, insulated (as built or unspecified)
116
3.2%
Modern wall (U-value from the design)
39
1.1%
Solid wall, external insulation
39
1.1%
Cavity wall, partly insulated
22
0.6%
Solid wall, internal insulation
17
0.5%
Cavity wall, internal or external insulation
14
0.4%
Solid wall, insulated
2
0.1%
Solid wall, partly insulated
2
0.1%
Heating
Homes
Share
Gas boiler
3,459
95.2%
Electric (storage heaters, panels, boiler)
116
3.2%
Communal heating
56
1.5%
Heat pump
2
0.1%
LPG
1
0.0%
Solid fuel (wood, coal)
1
0.0%
Loft / roof insulation
Homes
Share
No insulation
609
16.8%
Under 200 mm
1,543
42.4%
200 mm or more
823
22.6%
Insulated (depth not recorded)
191
5.3%
Flat or other home above
444
12.2%
Other
25
0.7%
Windows
Homes
Share
Double glazed
3,542
97.4%
Single glazed
84
2.3%
Triple glazed
6
0.2%
Secondary glazing
3
0.1%
CD
Energy rating: B 51 (1.4%) · C 1,272 (35.0%) · D 2,022 (55.6%) · E 264 (7.3%) · F 23 (0.6%) · G 3 (0.1%). Houses and bungalows: 77% of the homes; solar panels on 0.6% of the certificates. Most common build period on the certificates: 1930-1949. Designated: 8 April 1998.
Compared with Barnet and England
Share of homes
The Watling Estate
All 16 areas in Barnet
England
Solid walls, no insulation
30.2%
48.2%
48.7%
Gas boiler
95.2%
84.8%
66.4%
Rated D–G
63.6%
—
56.5%
Caveats
Certificates describe a home when it was assessed; 71% of these are from 2020 or later (latest 30 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 Barnet if in doubt.
Boundary: London Borough of Barnet via planning.data.gov.uk (entity 44002420, reference CA04, 149.2 ha); the council's appraisal or map. Homes are placed by the coordinates of their UPRN (OS Open UPRN); addresses are not shown.