Changing your windows to improve your EPC rating: a miracle solution?

Since the “Climate and Resilience” Act adopted in 2021, the regulations in the field of energy performance have been tightened and, progressively, poorly rated homes (described as energy sieves) are being banned from being rented out. As an owner, it is normal to seek to improve the results of your energy performance certificate and to consider energy renovation works.

RITMODiag invites you to take stock of the real impact of these works within the context of the energy renovation of your property.

How to deal with a poor EPC rating?

Has your home been rated E, F or G following the energy performance certificate?
It should be noted that since 2023, homes with a G rating can no longer be put up for rent on the property market, and this ban will be extended to F-class homes in 2028 and E-class ones in 2034.

Beyond the regulatory constraints, a poor energy class can devalue a property. So faced with this situation, the most appropriate solution is to carry out renovation works that will allow you to improve the energy performance of your home.
The temptation can be strong to carry out only small, quick and easy energy renovation works. But this approach does not always deliver the miraculous results hoped for.

Improving your EPC with energy renovation works

Before doing everything to improve your EPC, you must manage to identify the real sources of heat loss within your home. These may be located at the level of the roof, the loft, the walls or indeed the windows.

But according to various studies, joinery, although important in the energy performance of the property, does not generally represent the main source of energy loss in the property: far from it! It is nonetheless a very widespread idea, because changing windows brings real comfort for the occupant that is visible and felt. But its role in improving the home’s energy class is minor.

Despite everything one may hear at present, an effective energy renovation generally prioritises the insulation of the walls or the loft before turning attention to the windows.

So, in general terms, which works should be prioritised to improve the energy performance of your property?

The best avenues to improve your EPC… and the false leads

The most impactful works to improve an energy performance certificate are generally:

• External wall insulation (ITE),
• Loft insulation,
• Roof insulation,
• Replacement of heating systems,

These works can gain your property several energy classes, whereas a simple change of windows will often only allow a limited improvement of the EPC.

So what are the real solutions for optimising your energy performance?

First of all, it is important to have an overall view of the possible works, because putting a plaster on an open wound will never be the solution, just as replacing windows on a poorly insulated building will not considerably improve the home’s energy performance!

All the more so as, without an overall view, carrying out small one-off works can lead to bigger problems: thermal imbalance and condensation problems within your house, for example.

As we mentioned above, insulation remains among the most cost-effective works in terms of improving your energy performance certificate. You thereby avoid a great deal of heat loss through the walls of your property or through the roof.

Changing your windows to improve your EPC, myth or reality?

The reality of the figures provides an unequivocal answer: according to ADEME (the French Environment and Energy Management Agency), in an un-insulated home, windows account for only 10 to 15% of total heat loss, compared with nearly 30% for the roof and loft, or 25% for the walls!

(source: Practical renovation guide: insulating your home. Document published by ADEME)

By replacing your current windows with very high-performance joinery (triple glazing), the energy gain only amounts to 5 to 8%. And this gain is not enough to move from one energy class to another.

To obtain a significant impact on the results of your home’s energy performance certificate, it is important to carry out renovation works targeted at the most significant sources of heat loss, such as the insulation of the walls and the loft.

Be careful! Replacing windows is by no means a pointless choice when renovating a property! Indeed, it remains entirely relevant where your home has very old windows (single glazing) or in order to improve comfort within the building and thereby avoid cold walls or draughts.

As with all your property diagnostics, it is essential to call on professionals to carry out the works within your property in order to benefit from the best results.

Find the balance between comfort and energy performance within your home

It is normal to want to find the optimal balance between energy performance, comfort and investment. A home can show a decent result on its EPC, yet present real shortcomings in terms of comfort: damp problems, a feeling of cold, and so on.

Before undertaking works, we advise you to take a comprehensive and precise approach by carrying out an energy audit. In this way, you will benefit from a genuine report on the sources of loss within your property but also from precise, costed and prioritised works scenarios. The scenarios may concern carrying out the works all at once, or in stages. This audit must state, at each stage of the works, the energy class that your home can reach.

As we have already mentioned, good insulation can change everything. Insulating the walls can cut heat loss through the walls by a factor of three, and loft insulation can considerably reduce energy losses through the roof.

Changing your heating system is also an option for finding this balance between comfort and energy performance. Replacing an old boiler that runs on oil or gas is a major lever for action! Installing a heat pump can gain you up to one or two classes on your energy performance certificate.

Every project is unique; to best understand your needs and bring you the best solutions, get in touch right away with the experts at RITMODiag and RITMOAudit.

Would you like to find out more? Contact RITMODiag right now

Benefit from professional expertise by calling on RITMODiag! We offer you a fully transparent visit at the earliest opportunity for your property diagnostics and EPC.

Our property diagnosticians support you in carrying out a complete analysis of your property. We also make auditors available to you for carrying out your energy audits.

Whether for sale, rental or simply to obtain various property diagnostics, our teams are ready to listen to you and offer solutions tailored to your project.

Anticipate the various regulatory deadlines right now and make sure to improve the energy performance of your property assets!