The gap between a home’s design energy rating and its actual gas and electricity use can be 40%, enough to add £400 a year to a typical bill. That discrepancy is now the target of a new policy push from the Innovation News Network, which reports that UK officials are exploring how to bring measured performance into building regulations and EPC assessments.
As Innovation News Network reports, the current system relies on a Standard Assessment Procedure (SAP) that calculates theoretical energy use based on building fabric, heating system, and assumed occupancy behaviour. It does not measure what the meter says. The result: a home can achieve a high EPC rating while leaking heat through unsealed ducts or being heated by a boiler that cycles inefficiently.
Who qualifies, and who doesn’t
The proposed shift to measured performance would affect every homeowner who relies on an EPC rating to make decisions. Currently, a ‘B’ rated home might still cost £1,200 a year to heat if the occupants run the heating differently than the model assumes. A measured system would compare actual consumption against a benchmark, flagging homes that underperform.
The government has not yet published a timeline. But the Building Regulations Advisory Committee has already recommended piloting measured energy performance in new-build homes from 2026. For existing homes, the plan is more tentative, officials are considering voluntary disclosure of real energy data during property sales, similar to the Energy Performance of Buildings Certificates used in some EU countries.
What it costs a typical 3-bed semi
If measured performance becomes mandatory, the immediate effect on homeowners is likely to be a more accurate picture of energy waste. A typical 3-bed semi with a ‘C’ rating might discover its real performance is closer to an ‘E’, meaning the owner has been overpaying by £200–£300 a year compared to the model’s prediction. The upside: targeted upgrades, such as draught-proofing or smart heating controls, would show a measurable payback rather than a theoretical one.
Ofgem data from 2024 shows that the average household spends £1,800 annually on gas and electricity. A 20% modelling error, common in SAP assessments, represents £360 of that. The Energy Saving Trust has long argued that measured performance would help households prioritise the most effective retrofits, rather than relying on generic recommendations.
The catch: data privacy and meter access
But the policy faces a significant hurdle: getting real consumption data from smart meters. While 60% of UK homes now have a smart meter, many are not transmitting half-hourly data. The government would need to mandate data sharing for EPC purposes, which raises privacy concerns. The Home Builders Federation has also warned that measured performance could penalise new homes that are still ‘drying out’, a process that increases energy use in the first year.
Yet the alternative, staying with a system that routinely overstates efficiency, is worse. A 2023 study by UCL found that 70% of new homes in England failed to meet their design energy targets when measured in use. That gap is a technical problem and a consumer protection issue. Households buying a ‘zero-carbon ready’ home are paying a premium for performance they may not get.
What to do now
Homeowners should not wait for the policy to change. The simplest step is to compare your actual annual energy consumption (from your bills or smart meter portal) against the modelled figure on your EPC. If the real number is more than 15% higher, you have a performance gap worth investigating. A thermal imaging survey or a professional airtightness test can pinpoint the leaks.
For those planning major upgrades, heat pumps, solar panels, or deep insulation, insist on a measured baseline before and after installation. That way, you know whether the £10,000 investment actually cut your gas use by 60% or only 30%. The government’s Boiler Upgrade Scheme does not require measured performance data, but savvy installers will offer it. Ask for it.
Households on standard variable tariffs can check their real energy use via their online account. The next step is to book an EPC assessor who uses in-situ testing, not just modelling. That option exists now, and it will give you the truth that current policy still hides.
Frequently Asked Questions
Check your annual gas and electricity consumption in kWh from your supplier's online portal or your annual statement. Then compare this to the 'estimated energy cost' figure on your EPC, the document should list a total kWh for heating, hot water, and lighting. If your real use is more than 15% higher, your home is underperforming.
Potentially, yes. If mandatory measured EPCs are introduced, homes that perform well in reality could command a premium, while those with a large gap between rating and actual use may see lower offers. Early adopters who close the performance gap now could protect their property's value.
