What a conservation area changes
Permitted development is the set of works that can go ahead without a planning application because a national order grants permission in advance. For air source heat pumps on homes in England, that order is Part 14, Class G. It applies across Liverpool, conservation areas included. What a conservation area adds is one more limit on where the outdoor unit can go.
Paragraph G.2(j) says that on land in a conservation area the unit must not be installed on a wall or a roof which fronts a highway, and must not be installed nearer to any highway bounding the property than the part of the house that is nearest to that highway. In plain terms: nothing on the road side of the house, and nothing in the front garden. Outside a conservation area the rule is looser; there, a road-facing wall is only ruled out above the ground floor.
Everything else in Class G applies as it does anywhere: one unit on a semi-detached or terraced house, two on a detached house, a size limit of 1.5 cubic metres on a house, no pitched roofs, a 1 metre margin on flat roofs, and the MCS 020 a) sound calculation. Since 29 May 2025 the size and number limits have been more generous than they were, which helps in tight yards where a larger single unit replaces two small ones.
Liverpool's conservation areas in numbers
The council lists 36 conservation areas and says they cover 9% of the city and protect about 19,000 properties. The national planning dataset holds all 36 with their references, CA001 to CA036, and most of their designation dates. The oldest, West Derby Village and William Brown Street, were designated in 1969; the most recent, Kensington Fields, in November 2007. Several were designated in a single batch on 24 April 1996, including Sefton Park, Princes Park, Mossley Hill, Lark Lane and Woolton Village.
On the map the areas cluster in three places: the city centre and waterfront (Albert Dock, Castle Street, William Brown Street, Duke Street, Stanley Dock, Rodney Street), the parks and avenues to the south (Sefton Park, Princes Park, Toxteth Park and the Avenues, Grassendale and Cressington Park, Fulwood Park), and the old villages further out (West Derby Village, Woolton Village, Gateacre Village, Childwall Abbey, Wavertree Village). Each has its own character, which is why the council publishes separate material for each.
Article 4 directions
An Article 4 direction lets a council withdraw particular permitted development rights in a defined area. Liverpool City Council's conservation page says that works in a conservation area may be subject to an Article 4 direction, so that changes to a building's external appearance may need planning permission even where they would normally be allowed. Directions name the rights they remove, so the question for a heat pump is whether a direction covering your street withdraws Part 14 Class G. If you live in a conservation area, ask the council before relying on Class G. The street check cannot answer that part for you.
Listed buildings and the World Heritage limb
Two more parts of Class G have a Liverpool angle. Paragraph G.2(i) takes listed buildings, and land within their grounds, out of Class G altogether. Planning data shows 1,569 listed-building records within the city boundary. A heat pump there needs planning permission, and the council's guidance is that listed building consent is needed as well where work affects the building's special character, inside or out.
The other part is the World Heritage limb of G.2(j), which treats a World Heritage Site like a conservation area. Liverpool's waterfront was inscribed in 2004, placed on the in-danger list in 2012, and removed from the World Heritage List on 21 July 2021. That limb therefore no longer applies anywhere in the city. The conservation areas covering the same streets still do.
Positions that usually work in a conservation area
| Position | In a conservation area | Rule |
|---|---|---|
| Back yard, on the ground | Can be permitted development | G.2(j) not engaged |
| Rear wall, any floor | Can be permitted development | G.2(j) not engaged |
| Flat roof of a rear extension, 1 m from edges | Can be, if that roof does not front a road | G.2(g), G.2(j)(i) |
| Front garden or forecourt | Not permitted development | G.2(j)(ii) |
| Front wall, any floor | Not permitted development | G.2(j)(i) |
| Side wall facing a road (corner plot) | Not permitted development | G.2(j)(i) |
When you need a planning application
If the plan fails any part of Class G, the heat pump can still go ahead, but with planning permission rather than permitted development. Applications go to Liverpool City Council. The council's validation guidance lists the plans and documents it expects. For a heat pump, the facts a decision turns on are the same ones Class G uses: the exact position, the unit's size and appearance, and the sound level at the nearest neighbour, so the installer's MCS 020 a) calculation and the product data sheet are the obvious documents to have ready. The site plan should show the unit in relation to the road and the neighbouring windows.
If you think the plan does meet Class G but want certainty, the alternative is a lawful development certificate: the council confirms in writing that the proposal is lawful without granting permission.
Whether a road-facing position matters depends on the street, which the street check helps you work out. For the home itself, terraces and flats looks at where a unit fits on a terrace or a block, and the Warm Homes: Local Grant in Liverpool covers the council scheme that can pay for the work in qualifying homes.