Flats and maisonettes are the most energy efficient property type in England and Wales, with a median Energy Performance Certificate (EPC) score of 74. That puts them a clear step ahead of most houses, which means lower energy bills and a smaller carbon footprint for anyone living in an apartment. For buyers, tenants, and landlords, this isn’t just a nice-to-know fact — it directly affects monthly costs, property value, and legal compliance.
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This article is general information only and does not constitute professional advice. For your specific situation, consult a qualified professional.
Apartments have a built-in advantage: less exposed surface area means less heat escapes. But that doesn’t mean every flat is efficient. The gap between a well-insulated new-build and a draughty Victorian conversion can be huge. Here’s what you actually need to know.
What Makes an Apartment Energy Efficient — and What Doesn’t
The term you’ll see most often is EPC, which stands for Energy Performance Certificate. Every property sold or rented in the UK needs one.
What I tend to notice is that many flat owners assume their property is efficient simply because it’s an apartment. That’s not always true — especially in older conversions where the building fabric hasn’t been upgraded. The leasehold structure of many UK flats can also complicate who pays for shared improvements like roof insulation or new windows.
The Real Cost of Energy Efficiency in Apartments
Energy efficiency isn’t just about EPC ratings — it’s about what you actually pay each month. The average SAP rating for English dwellings hit 67 in 2023, up from 45 in 1996. That’s real progress, but the gap between the best and worst flats is still wide.
New dwellings in England now emit just 1.2 tonnes of CO₂ per year, compared to 3.2 tonnes for existing homes. For a flat owner, that difference shows up in heating bills. A poorly insulated flat in a building with single glazing and an old boiler can cost hundreds more per year to heat than a modern equivalent.
The average cost to bring a dwelling up to EPC band C is a key figure from the English Housing Survey, though the exact amount varies by property type and region. What’s clear is that the upfront cost is usually lower for flats than for houses, because there’s less roof and wall area to treat.
Regional variation matters too. London, the East of England, and the South East all have a median EPC score of 70 (Band C). Yorkshire and the Humber sits at 68 (Band D). If you’re buying or renting a flat in a colder region, the efficiency gap hits your wallet harder. A set of thermal curtains is a cheap fix, but it won’t make up for missing cavity wall insulation or a leaking roof.
Common Mistakes Flat Owners and Buyers Make
Ignoring the EPC before making an offer
Many buyers fall in love with a flat’s location or layout and never check the EPC until late in the process. By then, the survey might reveal that the building has solid walls with no cavity to insulate, or that the heating system is nearing the end of its life. The EPC tells you this upfront. A flat rated D or E might need thousands in improvements — factor that into your offer from the start.
Assuming all flats are equally efficient
Flats and maisonettes have a median EPC of 74, but that’s an average. A ground-floor flat in a Victorian conversion with single-glazed sash windows can score below 50. A top-floor flat in a 2015 block with mechanical ventilation and heat recovery can hit 85. The difference in annual heating costs between those two could be £400–£600. What I’d do is check the EPC register before viewing — it’s free and takes two minutes.
Overlooking shared building fabric
In a leasehold flat, you don’t own the roof, the external walls, or the communal heating system. If the building needs new insulation or a boiler replacement, the freeholder decides when and how — and you pay via service charges. Some leaseholders have faced surprise bills for major energy upgrades they didn’t choose. Always ask what the building’s long-term maintenance plan looks like before buying.
Thinking smart meters solve everything
Smart meters track usage, but they don’t improve efficiency. The English Housing Survey tracks smart meter installation by tenure, and while they help you understand your consumption, they won’t fix draughts or upgrade your boiler. Use the data from a smart meter to identify waste, but don’t mistake awareness for action.
How to Improve Your Flat’s Energy Efficiency — Step by Step
Start with the EPC recommendations
Every EPC comes with a list of recommended improvements, ranked by cost and impact. These are specific to your flat and building type. For a typical flat, the list might include cavity wall insulation (if applicable), loft insulation, boiler upgrade, double glazing, and draught-proofing. Each recommendation includes an estimated cost and annual saving. Follow this list in order — it’s based on a professional assessment, not guesswork.
Target the biggest heat losses first
In most flats, the biggest heat loss is through windows and walls. If you own the flat and have permission from the freeholder, secondary glazing or heavy curtains can help. For rented flats, ask your landlord about draught-proofing — it’s cheap and doesn’t require structural changes. The government’s Energy Company Obligation (ECO) scheme can fund some improvements for eligible households, so check what’s available before paying out of pocket.
Upgrade the heating system
Boiler upgrades from standard to condensing combi models are one of the most common efficiency measures driving improvements, according to the English Housing Survey. If your boiler is more than 15 years old, replacing it could cut your heating bill by 20–30%. For flats with electric heating, storage heaters have improved significantly — modern models are far more efficient than the old brick-filled units.
Understand the future regulatory landscape
The minimum EPC standard for rented properties is moving to Band C. That’s already law for new tenancies from 2025, and existing tenancies follow by 2028. If you’re a landlord with a flat rated D or below, you need a plan now. The cost to improve can be spread over time, but waiting until the deadline could mean a period where the flat can’t be legally let. For owner-occupiers, there’s no legal requirement to improve, but a higher EPC rating adds resale value and lowers bills.
If you’re unsure about your legal obligations as a landlord or leaseholder, it’s worth getting specific advice on rental property compliance from a qualified professional.
Frequently Asked Questions
Can I improve my flat’s EPC without the freeholder’s permission? ▾
What EPC band do I need to rent out my flat? ▾
Are new-build flats always more efficient? ▾
Who pays for energy upgrades in a leasehold flat? ▾
Does a higher EPC increase my flat’s value? ▾
What’s the cheapest way to improve my flat’s efficiency? ▾
Energy Efficiency Is the New Normal for Flat Owners
The direction of travel is clear. The proportion of English dwellings in bands A–C has more than doubled since 2013, and flats are already ahead of the curve. But the gap between the most and least efficient apartments is still wide, and the regulatory pressure on landlords is only going to increase. For anyone buying, selling, or renting a flat, the EPC is no longer a background detail — it’s a central factor in the transaction. Ignoring it costs money.
Remember: this article is general information only. For advice on your specific situation, speak to a qualified professional.
If this was useful, you might also want to read New Build Apartments in the UK: Are They Worth the Hype and the Price?
Sources and Further Reading
Ground Floor vs Top Floor Flats: The UK Apartment Debate Rages On — Explores how floor level affects heating costs and natural light, both tied to energy efficiency.
Buying a London Flat: These 5 Mistakes Could Cost You Thousands — Covers hidden costs including service charges for building maintenance and energy upgrades.
Gov.uk (2024). Chapter 2: Energy Efficiency — English Housing Survey 2023 to 2024. 🔗
ONS (2025). Energy efficiency of housing in England and Wales. 🔗
Department for Energy Security and Net Zero (2026). Household Energy Efficiency Statistics. 🔗
