Guardian reporter shares two-year real-world test on whether AI smart thermostats reduce heating bills

On 7 November 2026, The Guardian published a report by Samuel Gibbs on a two-year experiment to see whether smart thermostats and AI can actually cut household heating bills. The piece opens by noting that manufacturers uniformly claim the answer is yes, quoting average savings in the 25%, or "£180 a year" range.

Gibbs writes that he initially doubted he could cut costs and still keep warm by putting tech in control, but the results surprised him. He also points out that those savings promises come heavily caveated, and with energy costs changing regularly, it can be very difficult to tell what is having an impact in a real home. To find out, he spent the previous two years comparing manual thermostats with AI-driven smart thermostat systems in his own residence.

The overall takeaway from the experiment is that the advertised savings are real, but only under specific usage conditions, with clear limitations in complex, everyday household settings. As of this article, the test results have been made public only through this single Guardian report, with no further updates on his ongoing testing mentioned in the piece.