Over half of all English homes now hold an Energy Performance Certificate rating of C or better — 56% of dwellings reached bands A to C in 2024, up from just 26% a decade earlier. That sounds like good news, but it also means nearly half of the housing stock still sits at D or below. If you’re apartment hunting, that gap matters directly to your monthly bills and long-term comfort.
I’ve been writing about UK property and personal finance for years, and the question I hear most often from buyers and renters is simple: how do I know if a flat will be expensive to heat before I move in? The answer isn’t always obvious from a quick viewing. Energy efficiency isn’t just about saving the planet — it’s about whether you’ll be spending an extra few hundred pounds a year on heating or shivering through winter because the building leaks warmth. Here’s what you actually need to know.
If you’re looking at apartments, the EPC rating is your single best shortcut. But it’s not the only thing to check. A flat might have a decent rating on paper yet still feel draughty if the building’s fabric is poor. That’s why I always suggest pairing the certificate with a few practical checks during a viewing. And if you’re buying rather than renting, you’ll want to think about budgeting for hidden costs of apartment ownership — energy upgrades can be a big one. A simple way to start is with a thermal leak detector to spot draughts yourself before you commit.
What an EPC rating actually tells you about an apartment
The most important thing to understand is that an EPC isn’t just a sticker — it’s a calculation based on how much it would cost to heat and light the property under standard conditions. The government’s Standard Assessment Procedure scores homes from 1 (highly inefficient) to 100 (zero energy cost). In 2024, the average SAP rating for English dwellings was 68 points, up from 45 in 1996. That’s real progress, but the average hides big variation between tenures.
Social rented homes are the most efficient sector, with an average SAP of 71 in 2024. Owner-occupied and private rented homes lag behind at 67 and 66 respectively. What I notice when advising friends and readers is that private rented apartments are the most variable — you can find a modern flat with an A rating next to an older conversion stuck at an E. That’s why you can’t rely on the postcode alone. If you’re buying, a poor EPC is a negotiating point. If you’re renting, it’s a direct line to higher bills. My first move would always be to ask for the full EPC report, not just the front-page grade, because the recommendations section tells you exactly what needs fixing and at what cost. For a deeper look at what else can catch you out, read our guide on what to know when buying an apartment in the UK.
Why energy efficiency matters more now than ever
From October 2030, every rental property in England and Wales must achieve at least an EPC C rating. That’s a massive shift from the current minimum of E. The government has set an investment cap of £10,000 per property for landlords to meet this target, and local authorities can fine non-compliant landlords up to £30,000 per property per breach. If you’re renting, this means your landlord is under pressure to upgrade — but it also means some may try to pass costs on through higher rent or sell up entirely.
For buyers, the implications are just as serious. A flat with a D rating today could become harder to sell or mortgage in a few years as lenders tighten their criteria. And the new Home Energy Module (HEM) assessment method, which replaces the old SAP, will give higher ratings to electric heating systems with smart capabilities over older gas and fossil fuel systems. That means a property’s rating could change when it’s reassessed under the new rules.
Consider this scenario: you’re looking at a ground-floor flat in a 1970s block with electric storage heaters and single-glazed windows. The current EPC says D. Under the new HEM assessment, that rating could drop to E or F because the heating system scores poorly. Your heating bills could be 30-40% higher than a similar flat with a modern heat pump. That’s not a minor inconvenience — it’s hundreds of pounds a year.
I’ve seen too many people fall in love with a flat’s location and kitchen only to discover six months later that the heating costs are eating into their savings. The energy efficiency of a building isn’t sexy, but it’s one of the few things you can’t easily change after moving in — especially in a leasehold apartment where you can’t replace windows or add external insulation without permission. A smart thermostat can help you manage usage, but it won’t fix a poorly insulated building.
Where people go wrong when choosing an energy-efficient apartment
Trusting the EPC grade without reading the full certificate
The front-page letter is useful, but it’s the detail that matters. The EPC report lists recommended improvements with estimated costs and potential savings. I’ve seen flats rated C that only got there because of cheap LED bulbs and a new boiler, while the walls and roof are completely uninsulated. That flat will still be cold and expensive to heat. The full report tells you whether the rating is built on solid fabric improvements or quick fixes. If the recommendations section is long and expensive, the property is a project, not a finished product.
Ignoring the heating system type
Under the incoming HEM assessment, electric heating systems with smart capabilities will score higher than older gas boilers. That’s a reversal of the old hierarchy where gas was king. If you’re looking at a flat with an old gas boiler, it might score worse under the new rules than a modern heat pump system. And if you’re a landlord, replacing a gas boiler with a heat pump qualifies for a £5,000 government grant through the Boiler Upgrade Scheme, which significantly reduces the upfront cost. Don’t assume gas is always the cheaper option anymore — the long-term running costs and regulatory direction are shifting.
Overlooking the building’s fabric and age
An apartment in a converted Victorian house might have beautiful high ceilings and original features, but solid brick walls are much harder to insulate than cavity walls. The EPC will flag this, but many buyers don’t realise that insulation upgrades can reduce household energy use by up to 25% with a payback period of 10-15 years. That’s a solid return, but only if you can actually do the work. In a leasehold flat, you may need the freeholder’s permission to install internal wall insulation or replace windows. Check the lease before you buy.
| Tenure Type | Average SAP Rating (2024) | % in Bands A–C (2024) |
|---|---|---|
| Social rented (local authority) | 71 | 74% |
| Social rented (housing association) | 72 | 74% |
| Owner occupied | 67 | 53% |
| Private rented | 66 | 51% |
Private rented apartments are the most likely to be in band E or below — 9% of private rented dwellings are rated E, compared to just 2% of social rented homes. If you’re renting, that’s a red flag. If you’re a landlord, it’s a ticking clock until 2030. A carbon monoxide alarm is essential in any property with a gas boiler, but it won’t solve the underlying efficiency problem.
Forgetting to check the building’s common areas
In a block of flats, the energy efficiency of your individual unit is only part of the story. Poorly insulated communal hallways, single-glazed stairwell windows, and unheated corridors all affect how much heat your flat loses. The EPC only covers the dwelling itself, not the shared fabric. Ask the freeholder or management company about any planned upgrades to the building’s envelope. If the block has a poor overall energy performance, your flat will always be fighting a losing battle.
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How to choose an energy-efficient apartment: a practical guide
Read the full EPC report before you view
You can find any property’s EPC on the government’s online register using the postcode. Don’t just look at the grade — scroll to the recommendations section. It lists specific improvements with estimated costs and potential rating improvements. If the report recommends solid wall insulation and new windows, that’s a £10,000+ project. If it only suggests LED bulbs and draught-proofing, the property is already in decent shape. This information is free and takes five minutes to check. It should be the first thing you do before booking a viewing.
Ask about the heating system and its age
Find out what type of heating the flat uses and when it was installed. A gas boiler older than 10 years is nearing the end of its efficient life. Electric storage heaters from the 1980s are energy hogs. Heat pumps and modern electric systems with smart controls score better under the new HEM assessment and qualify for government grants. If the seller or landlord can’t tell you the age of the system, that’s a warning sign. You can also check the boiler’s service record — a well-maintained system is more efficient than one that’s been neglected.
Check insulation levels and window quality
During a viewing, look for signs of poor insulation. Cold walls, draughty windows, and single glazing are obvious red flags. Ask whether the property has cavity wall insulation, loft insulation (if it’s a top-floor flat), and double or triple glazing. The EPC will tell you this, but it’s worth confirming with your own eyes. If the windows are original and single-glazed, replacing them could cost several thousand pounds. In a leasehold flat, you may need the freeholder’s permission, and the cost might be shared through the service charge.
Consider the building’s future compliance
If you’re buying a rental property, the 2030 deadline is non-negotiable. Work out whether the flat can realistically reach EPC C within the £10,000 investment cap. If the property is valued at less than £100,000, the cap drops to 10% of the property’s value. Some properties — particularly those with solid walls or listed building status — may qualify for exemptions, but the process requires evidence and registration. Don’t assume you’ll get an exemption. Plan for compliance or factor the cost into your offer.
- 1Check the EPC onlineVisit the government’s EPC register, enter the postcode, and download the full certificate. Focus on the recommendations section, not just the grade.
- 2Inspect the heating systemAsk about the boiler or heat pump’s age, type, and service history. Modern electric systems with smart controls score better under new rules.
- 3Check insulation and windowsLook for cavity wall insulation, loft insulation, and double glazing. Single glazing and cold walls are expensive to fix in a leasehold.
- 4Plan for 2030 complianceIf buying to rent, calculate whether the property can reach EPC C within the £10,000 cap. Factor upgrade costs into your budget or offer.
For a more detailed look at what can go wrong after you move in, read our guide on snagging list secrets to avoid costly mistakes. And if you’re dealing with a leasehold property, the strata title regulations can affect what improvements you’re allowed to make.
Frequently asked questions about energy-efficient apartments
Can I be evicted if my landlord doesn’t meet the 2030 EPC C target? ▾
Does a higher EPC rating always mean lower bills? ▾
What if the apartment is listed or in a conservation area? ▾
How long is an EPC valid for under the new rules? ▾
Can I improve my flat’s EPC rating without the freeholder’s permission? ▾
What’s the cheapest way to improve an EPC rating by one band? ▾
Energy efficiency isn’t the most exciting part of apartment hunting, but it’s one of the few things that affects your comfort and finances every single day. Start with the EPC, check the heating system and insulation, and always think about what the building will look like under the 2030 rules. If this was useful, you might also want to read building insurance woes: a UK apartment owner’s insurance checklist.
Sources and Further Reading
10 essential tips for buying fixtures in your UK apartment — A practical guide to what you can and can’t change in a leasehold flat, including energy-related fixtures.
Understanding tenant rights when buying a condominium — Covers your legal position on repairs and improvements in shared ownership buildings.
English Housing Survey 2024 to 2025: Chapter 2 — Energy Efficiency. Ministry of Housing, Communities and Local Government, 2025.
2026 Changes to EPC Energy Efficiency Rules for Rental Properties. Anthony Jones, 2025.
Sustainable Home Practices UK 2026. Home Energy Model, 2025.
