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Blog Post 6 August 2020 Updated 29 October 2020

Turning a home extension into an energy saving opportunity

Home extensions are an attractive idea: they add space and value, plus often improve the look of a place. But a bigger home means more space to heat, which could increase costs and carbon dioxide (CO2) emissions. We look at how you can achieve the spacious and warm rooms you want, while adding long-term energy efficiency measures as you extend.

Building regulations stipulate that you have to include certain energy efficiency measures when extending, such as:

  • insulating cavities and floors (plus lofts if you have one)
  • making provisions for low-energy lighting wherever possible
  • installing thermostatic valves on any new radiators.

As the homeowner, it’s your responsibility to comply, so you should always confirm with builders at the start that they’ll handle the calculations on your behalf.

Building in insulation

Whether you want to do your part to lower your carbon footprint, improve the comfort your home, or maybe you are looking for ways to reduce your energy bills, adding an extension can be the perfect time to consider the other options to improve your home’s overall energy efficiency.

While the builders are in, you could consider installing wall insulation throughout your home. Sharing some of the costs and hassle with the extension can help make the insulation installation more financially attractive, while making all rooms warmer and potentially bringing fuel bill savings of £145 to £375 or more a year, depending on your home*.

Adding external wall insulation throughout gives the extension and the rest of the home the same look, and a good render can make your home weatherproof for years.

Heating the new spaces

Ensuring you can heat your extension affordably is a key issue. Increasing your floor space may mean you need to upgrade your heating system.

With the transition away from fossil fuels gathering pace, this could be the time to look at whether renewable heat is right for your home. Alternatively, if you decide to upgrade your boiler, aim for the most energy efficient model.

At a minimum, installing a thermostat, programmer and thermostatic radiator valves can save you £75 a year on fuel bills and help to control the amount of heat you need.*

But there are less technological matters to think about too. The layout of your new room is key; try to keep radiators away from bulky items like sofas or sideboards, so they can warm up the space most effectively.

Tackling draughts

Another area to consider is how heat moves between your existing building and an extension. Some extensions, such as conservatories, won’t be heated and so it’s essential to ensure good draught-proofing between the heated and non-heated areas.

Once again, this is an opportunity to think beyond the extension itself and cut out draughts around the entire home. Draught-proofing windows and doors could save the typical household around £25 off its annual energy bill.*

Your extension must have windows and doors that meet minimum heat loss standards and you should try to get the best energy performers you can afford. In the case of windows, A+-rated double-glazing can save £95 a year over single glazing.*

Energy efficient lighting

LED lighting comes in a range of fittings and colours to provide the finishing touch to your energy efficient extension, and up-front costs have dropped considerably as the technology has gained in popularity.

In a typical home, replacing all bulbs with LED equivalents would cut the lighting bill by around 69%, saving around £39 each year.**

You can see which the best performing LEDs in different categories are by visiting the Topten UK site.

An extension is a big investment for any homeowner but it provides an excellent opportunity to make your whole home more energy efficient. Even if you can’t make all the changes suggested here, a few could make a big difference.

* Saving figures throughout assume a gas-heated, 3-bed semi-detached house replacing single glazing with A+ rated double glazing. Gas price of 4.17p/kWh.

**Saving assumes a 3-bed semi-detached house replacing all bulbs with LED equivalents. Electricity price of 16.36p/kWh. Saving does not include cost of replacement bulbs.

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Last updated: 29 October 2020