The headline figures, drawn from Climate Change Committee analysis and summarised by the UK Green Building Council, are these: to hit the 2050 target, at least 15 million homes need one or more insulation measures, around 8 million need draught-proofing, and some 21 million need to move off a gas boiler.

National numbers like that are hard to act on. So here is the same question asked of one building type we survey constantly — the London mid-terrace, built somewhere between 1880 and 1910, solid brick, gas combi, mostly double glazed.

What that house actually needs

  1. Loft insulation to current depth. The single cheapest win, and still routinely missing or compressed to half its useful thickness by decades of storage. If there is a loft, this is first.
  2. Draught-proofing. Suspended timber floors, letterboxes, loft hatches, redundant chimney flues. Cheap, undramatic, and it changes how the house feels more than the certificate suggests.
  3. Heating controls. A room thermostat and thermostatic radiator valves. The assessment software rewards these and so does your bill.
  4. Solid wall insulation — carefully, or not at all. This is the expensive one, the one that moves the band most, and the one with real moisture risk if done badly. Internal insulation costs you room size and needs the ventilation strategy thought through. External is usually impossible on a front elevation in a conservation area.
  5. Heat pump — last, not first. A heat pump in an uninsulated, draughty house is an expensive way to be disappointed. This is why the Boiler Upgrade Scheme generally expects insulation recommendations dealt with first.

The order is the whole point

Note that the list is sequential and that the cheap items come first. That is not an accident of budgeting — it is building physics. Every measure you fit changes how the next one performs, and the fabric measures change it most.

The corollary is that anyone who quotes you for step five without asking about steps one to four is selling, not advising.

If you want to know which of those five your own house needs, that is exactly what an assessment produces. We cover east and south London and you can book online.