Money Saving Expert (MSE) has said there is no definitive answer to the annual question of whether to leave the heating on all day, but it has offered guidance to help households decide based on their heating system.
The website, founded by Martin Lewis, addressed the debate in August 2025, stating: “We wish we could give you a definitive answer, but this question is far more complex than it first seems, and we're not heating engineers or physicists.”
MSE added: “So please ignore clickbait publications erroneously crediting Martin with an answer - he knows a lot (too much) about energy bills, but this one isn't his or our bag. Ultimately, there are arguments for and against it, and it'll likely depend on the type of heating system, your usage pattern, and what type of home and insulation you have.”
Boiler vs heat pump advice
For households with a boiler, which most still have despite the growing popularity of heat pumps, the Energy Saving Trust recommends turning the heating on and off rather than leaving it on all day.
The Trust said: “If you have a boiler, then no - keeping your heating on all the time will use more energy and cost you more money. It’s more energy efficient, and better for your bills, to have your boiler come on when you need it.”
However, for those with a heat pump, the opposite approach could save money. The Trust added: “But if you have a heat pump, then you can save money by leaving the heating on all day. Check out our advice on how to improve your heat pump’s efficiency.”
Try an experiment to compare costs
MSE also highlighted the ‘low and slow’ method, which works best with modern boilers. This involves setting the boiler to a lower constant temperature, such as 18C or 19C, rather than turning it on and off throughout the day, which could help the boiler recover waste heat and operate more efficiently.
The site suggested a practical way to determine the best approach: “So perhaps the best advice is to try an experiment. Try a few days or a week with your heating on a constant low setting and then try only having the heating come on as and when you need it over the same time period and compare the energy use. Take meter readings at the start and end of each period and compare.”
