Independent · Engineer-led · Measured, not assumed
Britain is buying heat pumps, solar and batteries on the strength of a promise. The Government's own data shows the promise and the delivered performance are rarely the same thing.
of monitored heat pumps in the Government's Electrification of Heat trial performed below their design rating.
Key facts — sourced
In the DESNZ / Energy Systems Catapult Electrification of Heat demonstration (~742 monitored homes, published December 2024), 91.9% of properties recorded in-use performance (SPF) below the design figure (SCOP) — a mean shortfall of −0.66, with the median running 17.9% below design. Independent analysis of more than 1,700 heat pumps under Ofgem's Renewable Heat Incentive found the design-versus-actual gap widening in the most recent installations. This is not opinion. It is the Government measuring its own programme.
Every commercial party in the chain is paid on the sale, not on the outcome. Comparison sites and lead-generators are paid per introduction. Manufacturers see only their own hardware. Suppliers sell the kilowatt-hours that inefficiency wastes. There is a structural disincentive to publish a system under-delivering — so, largely, nobody does.
The way home-energy performance is certified is changing. The Standard Assessment Procedure behind today's estimate-based EPCs is being replaced by the Home Energy Model, and reformed, multi-metric certificates — including heating-system performance — are scheduled for the second half of 2027. The conversation is moving from what a system was promised to do, to what it actually does.
Forty years in high-hazard process engineering teaches one habit above all: you do not assume performance, you measure it. A designed figure is a hypothesis. The meter is the truth. SavingEnergy.com exists to hold that line for the British homeowner — plainly, independently, and with no product to sell you.
Sources: Electrification of Heat Demonstration — Heat Pump Performance Data Analysis Report (DESNZ / Energy Systems Catapult, Dec 2024); In-Situ Heat Pump Performance, Ofgem RHI data 2017–2022 (Nov 2024); Home Energy Model — replacement for SAP (GOV.UK consultation).
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