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Turning a home extension into an energy saving opportunity

•  Space and warm rooms key issues for householders
•  Going beyond Building Regulations can bring gains
•  Insulation, heating and lighting to tackle as you extend

In the last three years, 16 per cent of homeowners have extended their property.

It can be an attractive idea: it adds space and value, plus often improving the look of a place. These are things that many are looking for. 

But more space means more space to heat, and that can come with added cost and greenhouse gas emissions.

Building Regulations stipulate that you have to take on certain energy efficiency measures when extending, like insulating cavities and floors (plus lofts if there is one), making provisions for low-energy lighting wherever possible, and installing thermostatic valves on any new radiators.

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

Kitchen extension

But beyond mere compliance, real advantage can be gained from seeing an extension as an opportunity in the life of your home to take affirmative action on reducing energy costs and improving comfort. This applies to both the extension itself, and also beyond. Think about investing in the most energy efficient options your budget can stretch to. 

First and foremost, building materials. It’s worth considering breeze blocks over bricks, with external wall insulation over the top. It’s a more efficient option, and with a good aesthetic finish to boot. 

While the builders are in, it might well be a good idea to consider installing wall insulation on the whole home. This saves on cost and hassle, while making all rooms warmer and potentially bringing fuel bill savings of £150 to £250 or more a year, depending on your home and heating system. 

These are not the only advantages of an all-over approach to wall insulation. External wall insulation gives the extension and the rest of the home the same look, and a good render can make your home weather-proof for years.

Heating the new spaces

Thermostatic valve

Making sure an extension is appropriately heated at an affordable cost is a key issue. If there’s more space to heat, it stands to reason that a more powerful boiler could be required, and if so, you should aim for the most energy efficient model. 

Electric heating is something of a ‘quick fix’ for those who don’t want to tamper with their existing heating system when extending. But electricity is the most expensive and carbon intensive fuel, so ultimately, you’d be better off updating heating systems and controls

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. 


Applying energy efficiency principles in your new kitchen

Home electrical appliances using more energy than stated

Europe’s new, old energy label

Tackling draughts

Kitchen window

It’s also very important to take care over how heat moves between the existing building and an extension. If it isn’t going to be heated, for example in the case of a conservatory, it’s instrumental to ensure good draught-proofing between the heated and non-heated areas. 

Again, it may well be a good idea to take this beyond the extension, and cut out those annoying draughts around the entire home. Draught-proofing windows and doors could save the typical household around £20 off their annual energy bill.

Further heat is lost through the windows and doors themselves– and you’ll have to install windows and doors that meet minimum standards. Once more, you should try and get the best energy performers you can afford. In the case of windows, A+-rated double glazing can save £75 a year over single glazing. 

Take the LED, kit the kitchen

Changing a kitchen lightbulb

As mentioned earlier, lighting is covered under Building Regulations, but it’s a good idea to look to the best possible options here – and in most cases, that’s going to be LED. 

LED lighting comes in a range of fittings and colours to fit whatever effect you’re looking for, and up-front costs have dropped considerably as the technology has gained in popularity. 

The long-term savings compared to other forms of lighting are significant – the lighting bill is cut by around 36 per cent every year - making them the best value for money overall. You can see which are the best performing LEDs in different categories by visiting the Topten UK site.

As you can see, there are plenty of ways you can use a push for more space in your home as a ‘trigger point’ for a more concerted effort on energy efficiency. Even if you can’t make all the changes suggested here, even a few could make a big difference.

If your extension is a kitchen, check out our recent blogs on choosing energy efficient appliances, which can bring significant energy and water savings.

Share your thoughts with us in the comments below, or tweet us directly @EnergySvgTrust.

Gary Hartley's picture
Gary Hartley is Energy Saving Trust's expert blogger. He has extensive experience researching and writing on a number of topics, with particular expertise in sustainable energy, policy, literature and sport. As well as providing regular blog content, Gary has also been published in numerous magazines and journals.

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I'm looking to refurbish and extend our 1980's house - we have solar panels and wish to optimise them into this project plus anything else that would make our home more energy efficient besides bringing it up to date and making it warm and comfortable.

I have a problem in that I don't know where to start. Well more so in finding a person such as an architect/project manager in my area that could take on this task. Can you advise how I can find such a person please?

I really do think that people on lower incomes shoul have grants for work to be done to cut greenhouse gases as well as helping them cut their energy bills.
There are an enormous amount of south facing roofs that could have solar panels again to cut greenhouse gases and cut people's fuel bills.
Investment should be made in to batteries where solar powered could be stored for both private individuals and any new public buildings minimising the use of coal and gases.

I need to learn more about external insulation. It is imperative that the style of home (arts and crafts) is not lost. There is no cavity, just double skin. Obviously cost is a real consideration. How does one find the best tradesperson for this job?