Independent · 32 London boroughs · Checked Aug 2026

Where it goes decides whether you can build it.

Heat pumps, solar, air conditioning and insulation on a London home. Every rule below is drawn where it actually applies — then checked against your own borough's planning record.

Annotated section through a typical London terrace 1.0m MIN Solar Loft Front slope Heat pump Air con Main block Closet wing Side return
Select a point on the drawing
Usually allowed

Solar on the rear slope

Permitted development on most London houses, including inside conservation areas — provided the panels sit close to the roof and aren't prominent from the street.

Projection · max 0.2m
Payback · 7–12 years
Grid sign-off · G98 under 3.68kW
Always allowed

Loft insulation

No planning permission, no conservation area issue, no Article 4 problem. It is also the fastest payback of anything on this site — and it lowers the heat pump capacity you need to buy.

Cost · £300–£600
Payback · 1–2 years
Permission · none needed
Depends on your borough

The street-facing slope

This is where permitted development most often stops. On a road-facing slope in a conservation area — and anywhere an Article 4 direction applies — you are likely to need a full application.

Application fee · £258
Decision · 8–10 weeks
Strictest borough · Islington, 40 of 42
Watch the boundary

Air source heat pump

The rule that decides most London installations isn't planning policy — it's the metre of clearance to your neighbour's boundary. On a terrace with a filled-in side return, that is often the whole problem.

Clearance · 1.0m from boundary
Unit volume · max 0.6m³
Grant · £7,500 (£9,000 off-grid)
Costs, not saves

Air conditioning

Worth being straight about: cooling adds to your bill. It buys comfort on the ten to twenty genuinely hot days a year, and most split systems will heat efficiently in winter too.

Install · £1,500–£3,000
Running · +£50–£80 a year
Grant · none for cooling only
Five points · tap to compare

Choose your technology

5 guides

Heat pumps

Costs, the £7,500 Boiler Upgrade Scheme grant, and whether your home suits an air or ground source system.

Read the guide →

Solar panels

Panel costs, export payments through the Smart Export Guarantee, and roof suitability for London terraces.

Read the guide →

Air conditioning

What a split system costs to install and run, and the planning rules that catch people out in conservation areas.

Read the guide →

Living in a flat?

Permitted development doesn't apply to flats — but balcony solar, communal systems and batteries do. What leaseholders can actually install.

Read the guide →

Insulation

Why loft and cavity wall insulation pay back in under 4 years — and the honest numbers on double glazing.

Read the guide →

The Borough Ledger

See all →

Our own compiled index of conservation area coverage and Article 4 planning rules — borough by borough, plus area guides where a neighbourhood differs sharply from its borough. This is the detail that decides whether a solar or heat pump install needs planning permission where you actually live. Compare all boroughs →

Chiswick, W4 Area guide Hounslow Ealing Richmond
£7,500
Boiler Upgrade Scheme grant for an air-to-water or ground source heat pump
0%
VAT on solar, battery and heat pump installs until 31 March 2027, no income limit
SEG
Ongoing payments for solar electricity you export back to the grid
£36k
Income threshold for Warm Homes: Local Grant — free upgrades via your council; ECO4 winds down 31 Dec 2026
Your numbers

See what your home could save

Enter your property type, current heating and bill — get an instant estimate across all four technologies.

Open the savings calculator →

How this site is funded

Plainly: right now, it isn't. This site currently earns nothing. There are no adverts, no sponsored placements, no affiliate links, and no paid listings anywhere on it. Where we point you to an installer, we send you to the official MCS certified installer register — a free public tool we have no relationship with and earn nothing from.

That may change. If we add affiliate links in future — where a partner pays us a fee for referring an enquiry — we'll say so here plainly and label them where they appear. What won't change is the editorial position: no installer will ever be able to pay to be featured, mentioned, or ranked ahead of another, and no commercial arrangement will alter the cost, grant or planning figures on this site.

The guides were researched and written before any of that was on the table. The numbers you see are the numbers, not a pitch.