It's easy to assume an older home is only expensive to heat. But the things that let the cold in during winter — thinner walls, older windows, small gaps around the frames — work against you in summer too. A home that's hard to warm in December is often just as hard, and just as costly, to run in July.
With UK heatwaves arriving more often, these running costs add up quietly, without most people noticing until the bill lands. The good news: it's simple to spot where the cost is coming from — and there's plenty you can do to cut it before the next hot spell.
What's driving your running costs in summer?
If the question is how much a home costs to run, the first thing that shapes the answer is how energy efficient it is.
And the single biggest factor there might surprise you — not the fuel it runs on, not its shape or size — but its age.
The Office for National Statistics has found that a property's age is the biggest single factor in how efficient it is.
Most older homes were built before insulation standards tightened, and were never designed with either extreme of weather in mind. That's why the same property can be draughty and expensive to heat in winter, then trap the heat and turn stuffy in summer — one underlying cause, driving running costs up all year round.
Summer costs creep up more quietly than winter ones. Fridges and freezers work harder in the heat, poor insulation or single glazing lets heat build up indoors, and the typical response to a hot spell is reaching for a fan. They're considered cheap enough to run, pennies for an evening — and according to Uswitch more than nine million UK homes now reach for one, more than ever before.
As UK summers get hotter, more households are turning to air conditioning to cope, and that's where the cost really starts to climb. Uswitch data shows that running a built-in unit through a heatwave can push costs up from around £3 a week to over £42.
So, the harder a home is to keep cool, the faster running costs add up — and an older, less efficient property is exactly the kind that has to work hardest.
Check your EPC: the quickest way to cut the guesswork
There's a quick way to know for sure how efficient a home is, rather than guessing.
An EPC — an Energy Performance Certificate — rates a UK home's energy efficiency, and every home has one. It's the clearest place to start when you want to understand what a property will cost to run.
Your EPC...
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Gives the property a rating from A to G.
A is the best: an A-rated home holds its temperature well, so it stays warmer in winter and cooler in summer for less, and costs the least to run.
G is the least efficient, where heat escapes fastest in winter and builds up fastest in summer, pushing running costs up at any time of year.
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States the age of the building.
Homes built between 45 and 80 years ago sit in the higher-risk band for overheating, whatever their letter rating.
Most people haven't looked at their certificate in a while, if at all. But it's completely free, and it's the quickest way to find where a home stands — and where the biggest opportunity to cut costs might be.
You can find your EPC by postcode on the government's EPC register.
Want to understand what your EPC means in more detail? Read our guide to EPCs and property searches.
Is your home still right for the long term?
Efficiency is only half the picture. The other half is size.
A larger property costs more to keep comfortable than a smaller one, and that cost applies to every room — the ones in daily use and the ones that aren't. Every room still draws its share of the bill, in the cold months and the hot ones alike.
And don't forget the hidden extra costs. Things like hot water systems, standby power, and ageing appliances often quietly add up regardless of season — take a moment to check what's really driving a bill, it may not be the boiler.
Assess not only how efficient your home is, but also how many rooms you're paying to run. Neither means a home is wrong for you — that's nobody's call but yours. But considered side by side, they show the full running cost of staying put, for winter and future seasons alike.
A smaller, more efficient home is often the single biggest cut to your running costs available — bigger than any tariff switch or gadget.
So, if the bills are becoming too high on a limited income, the upkeep too much, and the thought of future temperatures brings dread, maybe it's time to consider a new home?
Nothing has to change tomorrow. But a home that's costly to run in every season is a cost carried for as long as you stay there. And if you're curious what moving to a newer home could look like, our guide on the benefits of moving to a new build property is a good place to start.
Quick wins to cut your bills now
In the short term, these few simple tips can help cut summer running costs instantly:
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Keep the heat out during the day
Keeping blinds closed during the hottest part of the day blocks solar gain, while opening windows at night allows cross-ventilation — a free way to keep a home cooler without extra appliances.
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Let appliances work for you, not against you
Running dishwashers, washing machines, and other high-draw appliances at cooler times of day (early morning or evening) reduces strain and can lower costs, particularly for anyone on a time-of-use tariff.
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Apply small, low-cost fixes
LED bulbs use around 75% less electricity than traditional incandescent bulbs and last up to 25 times longer, and are one of the simplest year-round swaps. Unplug standby electronics that continue to draw power in standby mode, and check your fridge and freezer settings (a fridge set to 3–5°C and a freezer to -18°C) to avoid unnecessary overcooling.
These small, immediate changes tend to feel more achievable than large-scale renovation — which matters for anyone trying to keep a home running affordably without disruption.
But really, the way to keep cutting your bills and avoid feeling caught out is to know where you stand now, and to assess what's right for the future.
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Know your property's energy rating — if you haven't checked your EPC yet, this is the place to start.
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Get a feel for the numbers — examine your bills and weigh up what the home costs to run across the whole year, not just in winter.
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Ask whether it still suits you — the right amount of space, in an efficient home, is the surest way to keep running costs down in every season.
Frequently asked questions
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What is a good EPC rating?
A or B ratings are the most efficient, meaning a home holds its temperature well and costs the least to run in every season. Most UK homes fall into the C to E range.
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How much does it cost to run air conditioning in the UK?
According to Uswitch, running a built-in air conditioning unit through a heatwave can cost as much as £42 a week, compared to around £3 a week in typical use.
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How do I check my home's EPC rating?
You can find your EPC for free by postcode on the government's EPC register. It takes a few minutes and shows your rating from A to G, along with the age of the building.
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Why do older homes cost more to run in summer as well as winter?
Older homes were often built before modern insulation standards, so they let heat in during summer just as they let heat escape in winter — driving up running costs at both ends of the year.
If you're beginning to wonder what else might be out there, our free guides offer a good place to start:
Over 60? A move could cost less than you think. When you're ready, explore what your options might look like and have a play with the figures using our free online calculator.
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