The rating is a model, so improving it is partly about improving the house and partly about improving what the model can see. Both matter, and knowing the difference saves real money.
The short version
Insulation and heating controls first, because they are cheap and score well. Keep the paperwork for anything already done, because an assessor cannot credit what cannot be evidenced. Leave solid wall insulation and renewables until the cheap points are gone.
Best value, roughly in order
- Loft insulation to current recommended depth. Low cost, strong effect, easy to evidence.
- Heating controls — programmer, room thermostat, thermostatic radiator valves. Cheap, and a property without them is penalised.
- Low-energy lighting in all fixed fittings. Nearly free points.
- Hot water cylinder jacket or factory-insulated cylinder, where applicable.
- Cavity wall insulation where walls are cavity and unfilled. Moderate cost, good effect.
- Draught-proofing and floor insulation, which help comfort and bills more than they move the number.
The part everyone misses: evidence
An assessor records what they can see or verify. If the loft is boarded over, insulation depth cannot be confirmed and a default assumption is used, usually a pessimistic one. If a boiler was replaced but there is no documentation and the data plate is unreadable, the same problem arises.
- Keep boiler installation certificates and Gas Safe or building control paperwork.
- Keep cavity wall and loft insulation guarantees or grant paperwork.
- Keep window installation certificates, which evidence glazing type and date.
- If the loft is boarded, leave a hatch or a lifted section so depth can be checked.
This is the single cheapest way to gain points: not doing more work, but making the work you already did visible.
Usually not worth it for the rating alone
Solid wall insulation moves the score substantially and costs a great deal, and done badly on an older solid-walled house it can cause interstitial damp and mould. It is a good measure in the right property with the right detailing, and a poor first move for a landlord chasing a letter. Renewables can help the score but rarely pay for themselves on that basis alone.
The order we would work in
Gather the paperwork, do insulation and controls at the next void, get a fresh assessment lodged so the register reflects the work, and only then consider fabric measures. If the house is showing damp, deal with that first: adding insulation to a damp wall makes both problems worse, and The Damp & Mould Man can tell you which you have.
Written by The Surveyor Co, a trading name of LW Renovation Group Ltd, Lincoln. This guide describes how records are written and read; it is not legal advice. Where a deposit scheme, lease or insurer sets a rule, that rule wins.