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Loft conversions and energy saving

living area in a loft conversion

Loft conversions are a popular choice to expand a home’s living space. Telltale skips and scaffolding are particularly prevalent in more expensive areas, where homeowners are anxious to make the most of any extra square footage. Some estimates put the number of loft conversions in London at around four in every ten houses.

But loft conversions don’t have to just be about space. Converting your loft is an ideal opportunity to tackle energy efficiency in your home. Could you, for example, use it as an opportunity to upgrade your lighting to high-performing LED lighting? Is your old boiler bringing you big heating bills? Perhaps it could be the ideal time for a change.

Going beyond the regulations

All loft conversions require approval from Building Regulations. As the householder, it’s up to you to get your conversion approved. However your contractors should support you through the approval process and provide you with any necessary calculations.

Energy efficiency is part of the standard building regulations, based on a calculation to minimise heat loss, called a U-value. Building regulations call for 0.18W/m2 or lower, which means you need to minimise heat loss from the conversion by insulating between and beneath the rafters, and maintain continuity of insulation between walls and the roof.

Many loft conversion companies will just put in the required minimum amount of insulation but it’s a good idea to ask for more insulation. Increased insulation can protect your loft conversion from extremes of temperature, save on energy bills and provide additional sound proofing.

Read our guide to roof and loft insulation to find out more. 

Choosing your energy extras

Insulating your loft without installing energy efficient windows would be a mistake. You want the highest performing windows that you can afford; A+-rated double glazing can bring significant bill savings, and you could go further still, with triple-glazing. Good quality windows not only bring lower bills and a warmer space, but excellent noise-proofing and reduced condensation build-up.

Loft conversion - windows on an empty room

Get to grips with heating

To stop the space becoming cold in winter, extra heating such as one or more radiators may well be required, but it would be wise to go for those controlled with thermostatic valves.

In general, it’s important not to forget to make sure the new heat source’s use is regulated, just like the rest of the house. There are a number of ‘smart home’ devices available now, with which you can control the heating of your whole property, even from your phone. This could well be a good opportunity to consider investing in some digital additions. If you don’t currently have any heating controls, upgrading your controls could save up to £120 per year on your heating bill.

Light up for less

Lighting accounts for 15 per cent of a typical yearly electricity bill, so again, using the loft conversion as an opportunity to take action elsewhere might be prudent. You can save £35 by replacing existing bulbs with LED equivalents – and if you want to know which LEDs are the longest-lasting, best of the best, visit Topten UK.

Solar power: the loft link

solar panels on a roof

A possible energy ‘add-on’ that’s unique to loft conversions is the opportunity to make a solar PV panels more economical to install. With reduced rates for the Feed-in Tariff (FITs), an incentive that pays for the electricity you generate and put back on the grid, you can improve return on investment by virtue of a less hi-tech aspect of installation: scaffolding.

During a loft conversion, scaffolding will already be up. It can be an expensive part of a solar installation, but with it already in place, you’re likely to be able to deduct from the fee charged by installers. Skylights can also be placed in a way to ensure the most panels can be fitted, bringing bigger benefits. If you’re thinking of getting solar panels, during a loft conversion is an ideal time because of convenience – you won’t need to get the builders in twice.

Of course, you’ll still need the right sort of roof to get the most out of solar – south-facing with a 30-degree pitch the absolute best – while it’s also worth considering your lifestyle. The more you are at home and using the electricity, the bigger bill savings you make, and the better investment solar is long-term.

Converting a loft throws up important questions about maintaining heat and keeping bills down while increasing space. But done right, it can also be the starting point for a closer look at your home, and some additional energy efficiency upgrades within your budget. 

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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.