Increasing your energy performance score to grade c

I have just spent a fun couple of days looking through the Energy Performance Certificates for two clients and for my own portfolio.


I was rather worried that we might all have to do a lot of work and spend a lot of money to get our properties up to EPC grade C, (minimum 69 points on the EPC score), to keep young Greta, BBC Climate Fruitcake Justin Rowlatt and the others in the Nut Zero fan club happy.

However, the situation was not as bad as I had feared.

The bulk of our portfolios consists of ex council houses, built in the 1970s (with cavity walls – a big plus as we shall see in a moment), and more difficult late Victorian/ early Edwardian “single skin brick properties”, mostly built sometime between 1890 and 1910.

The energy performance certificates were issued at various times in the last ten years, so some are now quite out of date – and since they were done, we have carried out improvements to the properties, in particular, installing new condensing boilers and double glazing.

The certificates for all properties are available online, so anyone can see what the last EPC score is for any property and what measures need to be taken to improve that score. This proved useful as I could not find all my EPCs in my filing systems. It is also helpful to see what neighbours with identical properties have managed to achieve EPC Score-wise!

The website where you can find EPCs is Find an energy certificate – GOV.UK ( Just plug in the postcode or address of any property in question and off you go!

The stated intention is that all new tenancies in rental properties must be EPC rated C or higher before 1 Jan 2026 and for all existing tenancies before 1 Jan 2029. So, if you have not done anything about it by the end of 2025, you had better hope your existing tenants don’t leave or you will have to do the improvements before you can let to someone new.

There are some hopes that the deadlines could be delayed, and the government is supposed to be publishing more on this matter soon, but timescales are slowly running out, so landlords need to be mindful that they will not want to be caught up in a rush to get improvements done before the deadline – there are only a limited number of competent tradespeople about.

So, how did my properties and those of my clients’ fare?

Well, it seems that for the later built properties – those with cavity wall spaces, things are OK. These will easily pass and possibly without me having to fill in the cavity walls, an idea I am not sold on. For me the early problems with the cavity wall filling materials are a concern – and though the materials are better now, I would prefer to wait a while longer and avoid having that done if I can.

That said, having the cavity filled generally gives you between 6 and 8 on the EPC score.

There seems to be a lack of consistency across reports and for some of my properties I am baffled as to why one got a higher score than I expected, and one got such a low one. (And the high scores were not necessarily due to me employing a Domestic Energy Assessor who happened to be a friend of mine either).

One assessor, commenting on the cavity wall insulation, said he was aware that some people get some holes drilled in the wall to make it look like they have filled the cavity wall. He added that the only way to check for sure is to try to look down on the wall from the loft space, but even then, it can be hard to see – and most assessors do not like getting in people’s lofts which are often very dusty and full of stored stuff, making this rather hard to do. Faced with that problem, many will just assume the cavity walls have been filled from the evidence of the drilled holes in the wall. Make of that what you will!

A quick win that I can easily do is to increase the level of loft insulation. For some reason, in the past 50mm or 100mm was deemed OK, but now the standard is 270mm. This can increase the EPC score by between 1 and 3, again depending on the assessor, the size of the space and how much insulation was there in the first place – and should cost less than a couple of hundred pounds. It is a job you can do yourself, but the hard bit is persuading your tenants to clear away any stuff they have in the loft so you can get in and do it. A nice box of chocolates may be called for, though it is of course in their interests and will save a bit of energy, though not that much, usually.

Then of course, having low energy bulbs in is an obvious, low cost and easy win – and will give you an extra one or two points.

Double glazing will raise the score by less than you think – for our standard two and three bed Victorian properties, doing this raised the score by 3 to 5 in most cases. It seems a shame to have to do this when the old single glazed windows can still have some time to run on the clock – and of course for those who believe the full “carbon causes global heating story”, one wonders about the carbon involved in making the new windows. We have opted to not decorate our old single glazed windows for a few years, so the money saved can go towards installing the new double-glazed windows.

Over time, we have been replacing our old gas boilers with new condensing boilers whenever we have been faced with a large repair. In the past, we might have done the repair and kept the old boiler going a bit longer but faced with the need to get the EPC score to at least a grade C, we are now replacing instead. The new condensing boilers raise the EPC score between 6 and 10 for our 2 and 3 bed houses, when combined with room thermostats/TRVs, (as of course they should be), though in one case, replacing the old gas boiler with a new condensing one, would apparently, give a lift of 13 on our EPC score.

It is hard to make sense of the actual EPC scores on similar buildings. There is clearly some margin and latitude given to assessors!

But all in all, doing this exercise put my mind at rest a bit. It seems that only on one property do I have to install both double glazing and a new condensing boiler. On two others, I will have to replace the boiler. On one of them that still has single glazing, the other measures I have put in should still get me over the line and allow me to score a grade C.

I would be most interested in hearing of the experiences of others on this matter.


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