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Will better insulation significantly improve my EPC rating?

ByDave Stopher

Aug 29, 2022

An energy performance certificate (EPC) shows how energy efficient your home is. It is important to know this information, since it will have an impact on how much you pay for your energy bills, how you can improve the energy efficiency of your home, what this will cost and how much money you can save in doing so. Your EPC will also note your carbon emission levels, helping you make more green and sustainable changes. 

It is also a legal requirement that you have a valid EPC of 10 years or less in place for prospective buyers or tenants if you decide to sell or rent out your property. For a qualified energy assessor to undertake the assessment and provide the energy performance certificate it will cost in the region of £75 – £120.  

The EPC certificate will then rate your property on a scale from A to G, with G being the lowest most inefficient rating and A the highest, which is awarded to a very energy efficient home.

A higher EPC rating can certainly add value to your property, as much as 14% if your home moves from a rating of G to A, according to Money Supermarket. When you consider that the average UK property price is £283,496, this is a boost of £39,689.44. 

When it comes to letting your property to tenants, it is also a legal requirement that any rental property has an EPC rating of E or higher. You could be subject to a fine for breaching the Domestic Minimum Energy Efficiency Standard (MEES) Regulations if you do not make the necessary energy performance upgrades before letting the property. Plans are in place to raise the minimum EPC score to a C rating for rental properties by 2030, so always make sure that you are familiar with the legal requirements for landlords before renting out your property. 

You can check if the EPC for your home is still valid here, and head to https://www.gov.uk/get-new-energy-certificate to arrange for a qualified energy assessor to undertake an EPC inspection and provide a new certificate if not. If you have made significant upgrades to your home’s energy efficiency since the EPC was last undertaken it may also be useful to have your home reassessed, especially if you are putting it on the market. If you are selling your home through an estate agent, they will often be able to expedite the EPC process for you, although this may come at an additional cost in comparison to finding an assessor yourself. 

Whether you are planning to make energy efficient upgrades to your home to improve your own lifestyle, or with a view to selling or letting the property, you may well wander what the best approach is to get the most bang for your buck, and whether an update like changing the insulation of the whole house can really make a big difference. 

In short, yes it can. 

It won’t be news to anyone with a boiler that has seen better days that you can significantly improve your energy performance rating and reduce your heating bills by installing a newer, more efficient model such as a ‘combi’ boiler, which combines heating and hot water, so a separate cylinder or tank is not required. Doing so can improve your energy efficiency rating by as much as 20 points. Solar panels are also popular with homeowners keen to save on their energy bills and flex their eco credentials at the same time. However, both of these energy efficient upgrades also come with a major cost implication, with a new boiler costing around £2,000 – 4,000 on average according to Checkatrade and solar panels coming in at a pricey £6,500 on average. Not really the kind of upgrades you want to make if you are not planning to hang around in the property to get your money’s worth.

In contrast, improving the insulation in the roof and walls of your home can be a more affordable way to make it more energy efficient and cut down on those all-important heating bills. Indeed, improving your roof insulation can add an additional 15-20 points to your EPC rating and doing the same for your walls can add another 5-10 points on average.

Insulating your loft and/or roof with a barrier of either glass fibre or a renewable wood fibre to stop heat escaping will cost around £800 on average and according to energy supplier EDF: “Good loft insulation can cut your heat loss by up to 25% – and your energy bills by up to £580 a year”. 

You should always choose loft insulation that is at least 270mm thick and if you plan to use your loft as a living space and want to keep this area toasty warm in addition to the rest of the house it may be useful to go for the slightly more expensive rafter insulation, rather than just installing insulation between the loft floor joists.  

When it comes to wall insulation, you will generally find that older homes in the UK have been built with solid walls, but homes built from the 1920s onwards tended to be built with cavity walls to reduce the likelihood of damp issues spreading into the house. However, it was not until the 1970s that cavity wall insulation became a standard feature, and it did not become compulsory for newly built homes until the 1990s.

Walls are insulated by injecting insulation material (generally mineral wool, polystyrene beads, or the pricier polyurethane foam) via small drill holes in the exterior walls which are then refilled with cement. The cost of installing cavity wall insulation obviously depends on the size of your home, but it will generally cost around £200 per (two-storey) wall according to Mybuilder.com, so for a standard, square built, detached home, it would cost in the region of £800.

Insulating cavity walls can certainly make your home more energy efficient, trapping heat and keeping out the cold, but installing insulation is not suitable for every property so make sure you do your homework and have the property assessed by a qualified insulation installer. You may also be eligible for a grant or loan to undertake the work as part of the government’s Energy Company Obligation (ECO) scheme so do check. 

As with any maintenance work that you have undertaken in your home, you should also always make sure you hire a company which is qualified to undertake the work to ensure that the job is done properly, and the right materials are used.

For more advice on energy efficiency and clean energy solutions, head to The Energy Savings Trust website: https://energysavingtrust.org.uk/