Listed properties and homes in conservation areas are protected for a reason. Their historical architecture, original windows, and traditional features give character to our cities and towns—but they also make it difficult to modernise.
EPC scores are particularly challenging for these homes. Why? Because many standard energy efficiency upgrades, like replacing windows or insulating external walls, are often not permitted. Planning regulations prioritise visual and structural preservation over performance.
That leaves owners with a limited toolkit. But that doesn’t mean there’s nothing to be done. Small, internal-only upgrades—especially those that are reversible—can still produce measurable EPC improvements without compromising the property’s protected status.
While listed buildings restrict what can be changed externally, many interventions on the inside of the home are fair game—so long as they’re non-invasive and don’t damage historic materials.
Here are some commonly permitted internal upgrades that EPC assessors value:
These upgrades share three key characteristics: they’re reversible, low-cost, and don’t alter the building fabric. For heritage homes, that’s essential. And when layered together, they begin to make a significant difference to EPC performance.
Among all the possible improvements, windows are often the biggest source of heat loss in older buildings. Single-glazed timber sash windows—common in listed homes—can leak heat rapidly, cause draughts, and lower internal surface temperatures, all of which negatively impact your EPC.
Yet replacing those windows is rarely allowed. Even if it were, doing so would remove a core architectural element of your home and likely cost tens of thousands of pounds.
That’s where secondary glazing becomes an essential tool.
Secondary glazing involves installing an additional pane or panel on the inside of your existing window, creating an insulating air gap that reduces heat loss, noise, and condensation.
Unlike double glazing, it doesn’t require removing or altering the original windows. It’s fully reversible, often tool-free, and does not breach listed building regulations.
This makes secondary glazing one of the highest-return EPC upgrades for heritage properties. It can lower U-values (a key EPC metric), reduce cold spots, and significantly cut down on winter heat loss.
Many secondary glazing systems still require drilling, screws, or adhesives—all of which can conflict with conservation rules. That’s why AirShield Glazing Panels are purpose-built for this exact challenge.
With AirShield Glazing, listed building owners get a thermal improvement without any compromise to their windows, walls, or legal standing.
EPC assessments now recognise the role of secondary glazing more accurately than they did in the past. U-value calculations have improved, and the effect of internal glazing solutions is more clearly reflected in scoring models.
Even modest reductions in heat loss through windows can translate into EPC gains of 3–6 points, often enough to move a property from Band D to Band C—the target threshold for most regulation.
This is particularly useful for flats or tenements in listed buildings, where external changes are impossible but internal optimisation is achievable.
Secondary glazing doesn’t have to act alone. It’s even more effective when used in combination with:
This layered approach is what EPC inspectors look for—evidence that the homeowner has made thoughtful, low-impact changes to improve efficiency.
For anyone living in a listed property or within a conservation area, EPC compliance doesn’t require massive disruption. In fact, the best strategies are often those that fit quietly into the home without being noticed.
Secondary glazing like AirShield Glazing Panels offers a rare combination of:
It’s not just a temporary fix—it’s a strategic move that prepares your home for future regulation while protecting its past.
As energy standards tighten across the UK, listed building owners face a growing challenge. But instead of feeling blocked by planning restrictions, it’s possible to work within them—cleverly.
By investing in reversible, compliant upgrades like AirShield Glazing Panels, you can boost your EPC, protect your comfort, and preserve the historical character that makes your home special.
