The Bill Archive Test: Reading a Flat’s Energy History Before You Sign

A flat can look cosy at a November viewing and still cost a fortune to keep warm in February. The trick is to stop guessing. Before you sign anything, ask for the flat’s energy history — not a vague promise that “the bills aren’t bad”, but actual usage figures or a full year of statements. This is the bill archive test, and it’s one of the most useful checks you can run as a renter.

Why the last bill isn’t enough

A single summer bill tells you almost nothing. A single winter bill tells you plenty, but it might be a one-off cold snap, a broken boiler, or a tenant who ran the heating with the windows open. You want the whole arc: autumn, winter, spring, summer. Twelve months of data shows you the flat’s real appetite for energy, including the awkward months when the heating goes on and the bills jump.

This matters more in 2026 because rents are tight and energy costs are still a serious line in any monthly budget. A flat that looks £75 cheaper per month can easily swallow that saving in gas and electricity. The bill archive test is how you compare the whole cost, not just the headline rent.

What to ask for — and what to ignore

Ask for the last 12 months of energy bills or, better, a supplier annual statement for the property. If the landlord or agent can’t provide that, ask for the annual kWh usage for gas and electricity, plus the heating and hot water system type. You want figures, not adjectives.

Useful things to request:

• Annual electricity usage in kWh, and annual gas usage in kWh if the flat has gas.
• The heating system: gas boiler, electric storage heaters, panel heaters, heat pump, or something else.
• Hot water: combi boiler, cylinder, immersion heater, or communal system.
• Meter type: standard credit meter, prepayment meter, or smart meter.
• A redacted copy of the latest bill showing standing charges and unit rates.
• If there’s a smart meter, the half-hourly or monthly data export from the supplier, if available.

Ignore the monthly direct debit amount on its own. Direct debits are a budgeting tool, not a true usage figure. A tenant might be underpaying and building up debt, or overpaying and waiting for a refund. The kWh numbers are the honest ones. Also ignore “energy efficient” in the listing unless it’s backed by the EPC and actual usage.

How to read a year of usage without an accountant’s brain

You don’t need a spreadsheet qualification. Start with the shape of the year. Does usage spike hard in winter? That’s normal, but a huge spike can point to poor insulation, electric heating, or a draughty flat. Does electricity stay high all year? That might be an immersion heater, old appliances, or electric heating that’s doing more work than you expected.

Then compare like with like. If you’re looking at two flats with gas central heating, compare annual gas kWh and annual electricity kWh. If one flat is all-electric and the other has gas, don’t compare the £ figures directly — compare total kWh and the heating system. A heat pump running at a decent efficiency can use fewer kWh than old storage heaters. A flat with electric panel heaters can be expensive to run even if the rent looks reasonable.

If you know the floor area from the EPC, you can do a rough sanity check: annual kWh per square metre. It’s not perfect, but it helps you spot a flat that’s wildly out of step with similar-sized homes. Ask the agent for the EPC floor area if it’s not in the listing.

Comparing heating systems fairly

Gas central heating is still common in UK flats, and it’s usually cheaper per kWh than direct electric heating. But don’t stop there. Ask how old the boiler is and whether it’s been serviced. A old boiler can still be safe but thirsty.

Electric storage heaters can be fine if they’re on an off-peak tariff, but you need to see how much of the usage is off-peak. If the flat has storage heaters and a standard single-rate meter, that’s a cost warning. Panel heaters and electric radiators are simple but can be pricey over a winter. Heat pumps are more efficient, but they work best in a well-insulated flat — ask for the EPC and any recent insulation upgrades.

Also ask about hot water. A combi boiler heats water on demand. A cylinder with an immersion heater can be expensive if it’s left on. A communal heating system can be convenient, but ask how the charges are calculated and whether you pay via the rent or a separate bill.

Smart-meter red flags

A smart meter is not a problem in itself. It can be genuinely useful. But it becomes a red flag when the data is vague or the setup is odd. Watch for:

• A prepayment meter that the agent glosses over. Ask why it’s there and whether you can switch to credit mode.
• Bills marked “estimated” for months on end. Estimated readings can hide real usage.
• No in-home display and no app access. You can still request data from the supplier, but it’s a hassle.
• Usage that jumps wildly between similar months with no explanation.
• A smart meter that “isn’t connected” or “doesn’t send readings”. Ask for manual readings instead.
• Electric heating paired with very high annual kWh and a weak EPC. That combination can be painful in winter.

If the landlord or agent can’t explain the meter setup, that’s your cue to ask more questions before you commit.

Word-for-word scripts that don’t sound awkward

Here’s an email you can send once you’re serious about a flat:

Subject: Energy usage for [address]

Hi [name],

I’m interested in [address] and I’m doing my budget properly before I decide. Could you send me the last 12 months of energy bills or the supplier’s annual statement for the property? If that’s not available, the annual gas and electricity usage in kWh would be really helpful, along with the heating and hot water system type. A redacted copy of the latest bill showing unit rates and standing charges would also be great.

Thanks, [your name]

If they send only a monthly direct debit figure, reply with this:

Thanks — that’s helpful for context, but I’m trying to compare actual usage. Could you send the annual kWh figures for gas and electricity, or a full year of statements? I don’t need any personal details, just the property’s usage and tariff information.

Keep it friendly. You’re not accusing anyone of anything. You’re just doing the maths before you sign.

When the numbers don’t arrive

Sometimes the landlord genuinely doesn’t have the bills because the tenant pays the supplier directly. In that case, ask for the EPC, the heating system details, and the meter readings at the start and end of the tenancy if available. You can also ask the current tenant — through the agent — whether they’d be willing to share an annual statement with personal details removed. Don’t expect it, but it’s worth asking.

If you get nothing at all, factor in a buffer. Use the EPC’s estimated energy costs as a starting point, then add a sensible margin for a cold winter and any electric heating. And ask yourself whether a landlord who won’t share basic running-cost information is someone you want to rent from.

The takeaway

The bill archive test is simple: ask for 12 months of real usage, read the kWh rather than the direct debit, compare heating systems fairly, and treat smart-meter vagueness as a prompt for more questions. It takes one email and a bit of patience. In return, you get a much clearer picture of what the flat will actually cost to live in — before you sign on the dotted line.