How can you improve a properties EPC rating?

In the future, it is almost guaranteed that rental properties will need to be an EPC rating C – when this happens is unknown, it could be 2 years time, it could be 8, but with the carbon emissions commitment, it’ll have to happen.

As a property investor myself, I’ve assessed all of my properties to understand the current landscape and to work out what needs to be done to achieve an EPC rating of C.

As an experiment, I took one of my properties, a traditional 2 bed mid terraced stone built property from the early 1900s with a rear extension adding in the 80s. I’ve adjusted various elements and documented them below to see the impact – the wall construction and size stays the same throughout. As an investor myself, I’m looking for a cost effective route to achieving a C rating with minimal disruption to the tenant.

As a side note, most EPC report recommendations will push for wall or floor insulation, or a solar installation – but these are not easy to do, very expensive, with lots of disruption and knock-on effects.

The property starts with a score of 66 which is a rating of D – we need to get to 69 for a rating of C.

Loft Insultation

At the moment, the level of loft insulation is unknown in the property, so adding the thicknesses below shows an impact of 2 or 3 points, adding 200mm of loft insulation at the joists is enough on its own for this property to get to a rating of C.

Joist Loft Insulation

  • 50mm = 68 D
  • 100mm = 68 D
  • 200mm = 69 C
  • 300mm = 69 C

Rafter Loft Insulation

  • 100mm = 68 D
  • 150mm = 69 C

So making sure you have 200mm of joist insulation might gain 3 points.


If the property didn’t have double glazing, it would have dropped to 63 points, which is a rating of D. It currently has double glazing, but an unknown date of installation (2002 is the key year) and even if it had double glazing installed/manufactured after 2002, it would still remain a score of 66 points, a rating of D.

So installing double glazing where there is none might gain 3 points.


There are already LED lights in all fittings at the property (100%) which gives the current 66 point D rating, having 50% or 75% of lights using LED drops the score to 65 D, 25% or no LED lighting gives a 64 point D rating.

So making sure you have 100% LED coverage might gain 2 points.

Heating Controls

The property has a room thermostat and a couple of TRVs on the radiators, however the combinations below show some potential gains.

  • Just a room thermostat on its own would remain the same with 66 points and a D rating
  • Just a boiler time programmer on its own would drop the rating by 3 points to 63, a D rating
  • Having a boiler time programmer, room thermostat, and TRVs on the majority of radiators would gain 1 point, to give 67 and a D rating

So making sure you have good heating controls might gain 3 points.


If the property didn’t have a Combi boiler, and still had the old style back boiler with a water cylinder, it would have dropped 12 points to 54 with an E rating. An older 2005 ish combi boiler would have dropped 1 point to 65 with a D rating, even a brand new combi boiler would still give the current 66 points with a D rating.

So, there you have lots of information about the impact on rating, some more expensive, like windows and boilers, but a lot less than wall or floor insulation or solar.

A lot of smaller changes, like loft insulation to 200mm, 100% LED lighting, and good heating controls might just be enough to move you up 8 points to the magic 69 needed for an EPC rating of C.