It’s no secret that British homes are feeling the chill. Drafts creep in through hidden gaps, walls leak heat like a sieve, and energy bills climb higher each season. Now, imagine waking up one crisp morning in a home that feels as snug as a country cottage—no need to layer jumpers, no creeping dread when the energy bill arrives. That’s the reality you could enjoy with internal wall insulation. And here’s the best part: there are grants available to help you make it happen.
At the Energy Grant Service , we’re on a mission to connect homeowners with the support they deserve. Through government initiatives like ECO4 and the Great British Insulation Scheme, many households can qualify for help to insulate their walls from the inside out. But you’ll never know if you’re one of the lucky ones unless you check.
A (Not-So) Hidden Problem
If you live in an older UK property—especially one built before the 1930s—there’s a good chance you have solid walls rather than cavity walls. Solid walls don’t have that handy gap in the middle where insulation can be injected. The result? A lot of wasted heat. Even more modern properties with poorly insulated interior walls can suffer from substantial heat loss.
You might notice cold patches in certain rooms, or you may find yourself constantly adjusting the thermostat, never quite feeling comfortable. When the weather turns frigid, your boiler or central heating system works overtime, devouring energy and racking up hefty bills. Meanwhile, the planet (and your wallet) take the hit.
Internal wall insulation offers a straightforward solution: install an insulating layer on the inside surface of your external walls. This helps lock in the warmth you pay for, meaning you’ll burn less energy to maintain a comfortable temperature. But don’t just take our word for it—ECO4 and the Great British Insulation Scheme both identify wall insulation as a top-tier upgrade to boost your home’s energy efficiency rating.
Why Internal Wall Insulation Matters
You might be thinking: Why not just do external wall insulation? Indeed, external insulation is another effective method. But for many homes—especially those in conservation areas or those with aesthetic or planning constraints—external insulation isn’t always feasible. Perhaps you love your property’s original brick façade or you live in a listed building. That’s where internal wall insulation comes into its own. By adding insulating material to the inside of your walls, you preserve your home’s exterior charm while significantly reducing heat loss.
The Great British Insulation Scheme Delivery Guidance underscores that insulating your walls can help push your property up the SAP rating scale, often from a D or E rating to a higher, more efficient band. That translates into real money saved each month. How much, you ask? Well, let’s crunch some numbers.
How much money can you save with Internal Wall Insulation
According to data from energy experts and industry bodies (like the Energy Saving Trust), a typical semi-detached home with solid walls could see savings of £200 to £460 per year on heating bills after installing internal wall insulation.
Terraced properties and flats can also benefit substantially, often saving £150 to £300 annually. Your exact savings will depend on your home’s size, construction, and existing insulation.
Now, imagine that extra money staying in your bank account rather than vanishing into the energy ether. Over a decade, you could be looking at thousands of pounds saved—not to mention the priceless comfort of a warmer, cosier home. It’s like giving yourself a pay rise, one that arrives in the form of reduced bills rather than extra paperwork.
And if you combine internal wall insulation with other measures—like loft insulation, cavity wall insulation, or even solar panels —you could multiply your savings. That’s precisely what the ECO4 and Great British Insulation Scheme are all about: encouraging homeowners to undertake a “whole-home” upgrade that maximizes energy efficiency.
Government Grants: How They Work
When we say “grants,” we’re referring to various forms of financial support, from partial subsidies to full coverage, depending on your circumstances.
ECO4—short for Energy Company Obligation—requires energy suppliers to help eligible households install energy-saving measures, including wall insulation. Meanwhile, the Great British Insulation Scheme extends similar benefits to a broader range of homes, focusing on those in lower council tax bands or those with lower energy efficiency ratings.
In a nutshell, if your home is eligible, you could get some or all of the cost of internal wall insulation covered. The same official guidance that covers Heat-Pumps and Boilers also applies to insulation measures. If you’ve got a leaky property that scores poorly on energy performance, you could be first in line for help.
But here’s the thing: eligibility varies. It’s influenced by your household income, your property type, and your existing energy efficiency rating. So let’s not play guesswork. Use our Eligibility Checker at the bottom of this page.
A few simple questions, and you’ll know if you’re in line for assistance—before you invest a single penny of your own money.
The Risks of Not Applying Through the Energy Grant Service
You might wonder: Why not just do it myself? Why not call up the cheapest installer in town?
Here’s why: going it alone can lead to nightmares that make your current heating bills look like pocket change.
Cut-Rate Installations: Some shady operators cut corners by using substandard materials or skipping essential prep work. You might get a bargain price, but the insulation could be less effective, leaving you with mediocre results and potential future headaches.
Moisture and Mould: Internal insulation must be fitted properly, or you risk trapping moisture between your newly insulated walls and the original masonry. That can lead to damp patches, peeling paint, and even structural damage. Worse yet, mold can become a health hazard.
Weeks of Scaffolding or Disruption: While internal wall insulation typically involves less external scaffolding than external insulation, poor project management can still leave your home in disarray. Walls stripped bare, furniture moved around for ages, dust everywhere… you get the picture. A professional approach minimizes disruption and ensures a swift, tidy finish.
Missed Funding: Even if you do qualify for a grant, an unregistered or inexperienced installer may fail to comply with the official guidelines, jeopardizing your funding. You could be left paying out of pocket
Here at Energy Grant Service, we work with certified installers who follow the official PAS 2035 standards (as referenced in ECO4 and Great British Insulation Scheme guidance). This ensures a robust process—from initial assessment to final inspection—designed to keep your home safe, sound, and energy-efficient.
The Step-by-Step Process
1. Check Your Eligibility: Scroll to the bottom of this page and click our Eligibility Checker. In just a few minutes, you’ll know whether you might qualify for a grant under ECO4, the Great British Insulation Scheme, or other relevant programs.
2. Arrange an Assessment: If you’re eligible, a qualified assessor will visit your home. They’ll examine your walls, check for existing insulation, and ensure your property is suitable for internal wall insulation. This step is vital—no guesswork allowed.
3. Tailored Proposal: Next, you’ll receive a detailed plan outlining the scope of work. If you’re approved for grant funding, you’ll see how much you stand to save. If partial funding applies, you’ll know exactly what your share of the cost will be.
4. Installation: A professional installer will then fit insulating material—often rigid boards or stud walls with mineral wool—onto your existing interior walls. They’ll finish with plasterboard or a smooth render, ready for decorating. Expect some redecoration to be necessary, but rest assured, a competent installer will keep disruption to a minimum.
Common Misconceptions
“It’ll shrink my rooms!”
Yes, internal wall insulation will eat up a little floor space—typically a few centimetres per wall. But many homeowners find the trade-off well worth the comfort and savings gained. If space is tight, a professional installer can recommend thinner, high-performance materials.
“It’s too messy!”
Any renovation has its mess. But a skilled team can complete each room in stages, minimizing disruption. Proper planning (and a good dust sheet) go a long way.
“It won’t make much difference.”
Quite the contrary. If your walls are uninsulated or poorly insulated, you could be losing 25% or more of your heat through them. Insulating them from the inside can be one of the most impactful improvements you’ll ever make.
“It’s only for old houses.”
While older homes benefit greatly, even newer properties can gain from additional internal insulation—especially if the existing insulation is subpar or has degraded over time.
Your home could be warmer. Your bills could be lower. And you could be contributing to the UK’s net-zero targets, all by making a single, straightforward improvement. Internal wall insulation isn’t just a building upgrade—it’s a lifestyle upgrade.
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