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The middle of summer may seem an odd time to think about insulating your home, even in the UK. But with energy bills likely to remain high for the foreseeable future, acting sooner to stop the heat from escaping from our homes can make a big difference, especially for those of us who live in poorly insulated older properties.
Most properties built before the 1920s have solid walls, while most built after this period have cavity walls. And, when left uninsulated, solid walls can lose twice as much heat as uninsulated cavity walls. Despite this, by the end of December 2022, fewer than one in 10 (9%) of properties with solid walls in Great Britain were insulated, according to the government’s Household Energy Efficiency statistics.
So why aren’t more of us insulating our solid walls, when the Energy Saving Trust estimates doing so could save a typical three-bedroom, semi-detached household £410 a year on energy bills?
A major investment
You can insulate solid walls either internally or externally. Getting internal insulation put in can lead to a lot of disruption inside your house, and once in place, you will lose a small amount of space in the rooms where it’s installed.
External insulation will change the appearance of your property’s exterior walls but could help protect them from the weather and any future damage. It also involves extensive work to install, and you may need to check with your local council to see if you need planning permission.
Either type of insulation could save a semi-detached household around £410 a year on energy bills, but both are expensive to install. For a typical property, the Energy Saving Trust estimates that internal insulation costs around £7,500 to set up and external insulation costs around £11,000.
Josh Jackman, lead writer at The Eco Experts, an energy-efficiency advice site, calculates that it will take 26.8 years, on average, to break even with external insulation and 18.3 years with internal insulation. “Considering solid wall insulation generally lasts 30 years or more, this is a pretty good result – if you have enough money for the upfront cost,” he says.
By contrast, cavity wall insulation may cost only around £2,700 for a typical semi-detached house, with an annual energy savings of £300, which means it could pay for itself in under 10 years.
Some of the cost of solid wall insulation could be absorbed by getting your walls insulated at the same time as other projects around the house, such as fitting a new kitchen or getting roof repairs.
With the expense and disruption of installing solid wall insulation, it’s perhaps not surprising that so many properties are left uninsulated – especially as there are more affordable ways to cut your energy bills.
Better value for money
If you have thousands of pounds to spend on energy improvements, there’s another option you might want to consider. Jackman points out: “Solar panels are in the same price bracket as solid wall insulation, costing £7,860 for the average three-bedroom house – but you’ll typically save £557 per year and break even in 14.1 years.”
However, the money you could save with solar panels depends on several factors, such as the time of day you use the most energy, and the cost of installation could put it out of reach for many homeowners. Thankfully, there are energy-efficient improvements that are cheaper and could give you a quicker return on investment.
Angela Terry, CEO of One Home, a climate change and energy-saving awareness group, says: “A quarter of heat is lost through an uninsulated roof, and nearly eight million homes have inadequate loft insulation. [Installing it] can be a relatively quick DIY job and, based on a typical semi-detached house, can save £285 a year.”
Even though it’s cheaper to install loft insulation yourself, it may still be worth getting a professional to minimise the chances of any issues with dampness or condensation. “An average cost to install using professional tradespeople is £930 – a three-year payback,” Terry says. “Crucially the benefits last for around 40 years.”
Some even simpler and cheaper ways to save energy don’t involve much work or expense. “Getting high-quality thermal curtains costs around £100 and will save you £245 per year, on average – a truly fantastic return on your investment,” Jackman says. You can also block any draughts around your windows and doors using insulation tape or draught excluders.
Help with costs
Homeowners with a low income who receive certain benefits and live in a property with a poor energy performance certificate (EPC) rating may be eligible for a grant through the government’s Energy Company Obligation (ECO) scheme. But be aware it is available only in Great Britain.
You can see if you qualify by applying through an energy supplier (not necessarily your own). If eligible, the energy supplier will assess your home, recommend upgrades and, if you go ahead, pay towards installation.
The Great British Insulation Scheme is similar to the ECO scheme, but it’s open to a wider group of households. To be eligible, your property needs an EPC rating of D or below and you need to be in council tax band A-D (England) or A-E (Scotland and Wales). However, at the time of writing, not all suppliers have opened the scheme for applications yet.
The Affordable Warmth Scheme and Sustainable Energy Programme can offer similar funding for homes in Northern Ireland.
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