The cheapest ways to improve an EPC rating are usually the paperwork for work already done, low-energy lighting, loft insulation, better heating controls and cylinder insulation. Most advice on improving an EPC rating is written by people who have never done an assessment. It leads with solar panels and external wall insulation, which are the two things almost nobody reading it will actually do. This is the opposite: the cheap, unglamorous measures first, because on the average London property they are what move the score.
Start by finding the paperwork
Before spending anything, spend an hour looking through your files. Where the assessor cannot verify a measure, the methodology requires assuming the worst reasonable case for the property’s age and construction.
That means a cavity filled ten years ago with no certificate is recorded as unfilled. Loft insulation topped up but hidden under boarding is recorded at whatever depth can actually be seen. Producing the documentation costs nothing and can move a rating on its own.
Worth hunting for: cavity wall insulation guarantees, loft insulation receipts, boiler installation and annual service records, window installation certificates, and anything relating to solar panels or a heat pump.
Lighting
The cheapest measure there is. The assessment counts the proportion of fixed light fittings with low-energy bulbs, so swapping the remaining halogens for LEDs is a genuine, if small, gain for the price of a few bulbs. Do it the week before the visit if you like; it counts on the day.
Loft insulation
The single best value structural measure in most houses. The assessment records depth, and the difference between a thin historic layer and a full modern depth is material. If your loft is boarded over an old thin layer, that is worth addressing properly rather than adding another layer on top of the boards.
This one has a real double benefit: it moves the score and it noticeably reduces what you spend on heating. Loft insulation and your EPC covers depths, costs and boarded lofts.
Heating controls
Underrated, and frequently the best return per pound on a London flat where the walls and windows are not going anywhere. A system with a room thermostat, a programmer and thermostatic radiator valves scores better than the same boiler with no controls at all.
If you have a modern boiler on a bare on/off switch, this is where I would look first.
Hot water cylinder insulation
If there is a cylinder, its insulation is recorded. An old cylinder with a thin jacket, or none, is an easy and cheap fix. A modern factory-insulated cylinder is already fine and needs nothing.
Draught-proofing and the fabric
Cheap, sensible, and it makes the property more pleasant to live in. Be honest with yourself about how much it will move a rating on its own, though — the methodology is not especially sensitive to it. Do it for comfort and bills, and take the score as a bonus.
What makes the biggest difference
Cavity wall insulation, where the property has unfilled cavities, is a substantial gain (is your home suitable?). Replacing a genuinely old and inefficient boiler is another. Both cost real money, and both are usually worth doing on their own merits rather than purely for the certificate.
Solid wall insulation and solar panels will appear on plenty of recommendation lists. They can be transformative for the score. They are also expensive, disruptive, and in a lot of flats simply not practical. Do not let a generated list talk you into one.
That is the everyday picture across East London, where so much of the housing is solid-walled Victorian and Edwardian terraces — the local pages for Manor Park and Newham go into what that means for the rating. When you are ready for a new assessment, an EPC is from £69.
Do solar panels improve an EPC rating?
Usually, yes. The rating is worked out from the home’s modelled running costs, and panels that make their own electricity bring those costs down, so the same home normally scores higher with them than without. How much higher depends on the size of the system, which way it faces, any shading, and the size of the home: the same system moves a small home further than a large one.
If the panels are already there, find the installation paperwork. The installer’s certificate gives the size of the system, which the assessment can use instead of an estimate based on how much of the roof the panels cover.
If you are thinking about panels only for the rating, price the cheaper measures above first. Panels are a big outlay, and on a lot of London homes, flats especially, there is no suitable roof to put them on.
Improving the rating of a flat
In a flat, the heating, hot water, controls and lighting usually matter more than the walls and windows, because those are the parts you can change. A flat with other homes above, below and beside it often loses less heat than a house to begin with, so the fabric has less to give.
Heating is where flats most often win or lose points. Old electric storage heaters on manual controls tend to score poorly; newer high heat retention storage heaters, or a gas boiler with a programmer, room thermostat and radiator valves, score better. An electric hot water cylinder with a thin jacket and no thermostat is another easy loss.
A top-floor flat with a loft above it can still gain from loft insulation. And if the building has had work done, such as cavity wall insulation or new windows, ask the freeholder or managing agent for the paperwork: without it, the assessment has to assume the worst reasonable case.
A realistic order of work
- Find and produce the paperwork you already have.
- Swap remaining fittings to low-energy bulbs.
- Sort out heating controls if they are missing or minimal.
- Insulate the hot water cylinder if there is one and it is bare.
- Bring loft insulation up to a proper depth.
- Fill unfilled cavities.
- Only then consider the large-ticket items.
That order suits most homes, not every one. If you would rather have it worked out for yours, I can add an Improvement Plan to your EPC for +£30: a written plan saying why the home scores what it does, which improvements would raise it and where to start, sent within 72 hours of the visit. If you are planning work first, the plan is also available on its own, from £89, with nothing lodged on the register, so the EPC you get afterwards shows the finished home.
Do I need a new certificate afterwards?
You are not obliged to get one just because you have made improvements. But the old certificate is the one sitting on the public register for a buyer or tenant to find, so if you have done meaningful work, a fresh assessment is usually worth it — here is what an EPC costs in London.
If you are close to a band boundary, it is worth asking before you book. Tell me the current score and what you have done, and I will give you an honest view on whether a re-assessment is likely to cross the line — there is no sense paying for a certificate that says the same thing.
If you think the rating on the current certificate is simply wrong, rather than out of date, here is how to challenge an EPC.
Where to go next
What the bands and the score actually mean, and if you let the property, the minimum standard you have to meet.