06/01/2026
Heating Myth Busted? Martin Lewis Finally Weighs In on the Question Everyone Argues About
The great heating debate is back and this time, Martin Lewis has stepped into the boiler room to settle it.
As temperatures drop and thermostats creep up, households across the UK are once again divided over a familiar question: should you leave the heating on all day, or switch it on only when you need it?
Supporters of the so-called "low and slow" approach swear by it, claiming that keeping radiators ticking over at a steady temperature warms homes more efficiently and avoids energy spikes. Critics, however, insist it is nothing more than an expensive myth.
Now, Martin Lewis’ MoneySavingExpert has taken a deep dive into the issue, pulling together evidence from the Energy Saving Trust, British Gas, an independent plumber, and feedback from MoneySavers on social media. According to reports from the Express, it is the most detailed guidance available so far.
The headline verdict from MSE is clear: "leaving the heating on all day leads to greater heat loss and means higher cost".
That sounds decisive, but the reality is more nuanced.
The Energy Saving Trust says that running heating continuously is generally less cost-effective. Its advice is simple: only heat your home when you actually need to, so you are not paying to warm empty rooms. Using a programmable thermostat is highlighted as the most efficient way to hit the right temperature at the right times.
However, Heat Geek offers a different perspective, arguing that the "low and slow" method can work better in certain homes. If you have a modern condensing boiler or a heat pump, are at home most of the day, or spend evenings and weekends indoors, a steady temperature could make sense. Modern boilers installed after 2005 reclaim waste heat before it escapes, while heat pumps draw warmth from the outside air.
In these cases, maintaining a consistent 18 or 19°C may actually improve efficiency. The key, according to experts, is resisting the temptation to blast the heating when you feel cold. Slower, steadier heating allows systems to operate more efficiently and recover more waste heat.
That said, this approach is not for everyone. If you are frequently out of the house, or if your walls are made of plasterboard which heats up quickly, switching the heating on and off may work better. Homes with cavity wall and loft insulation, or underfloor heating, are more suited to the "low and slow" method.
There is also the condensation argument. Some experts believe that keeping a consistent background temperature reduces moisture build-up in walls, which can otherwise transfer heat outside and contribute to damp and mould.
So who is right? According to MSE, there is no universal answer.
Instead, households are encouraged to test both methods themselves. Take meter readings at the start and end of each approach, compare the results, and try to ensure the outside temperatures during each test week are similar.
In other words, the heating debate is not over yet. The answer might depend less on opinion, and more on your home, your habits, and what your meter tells you.
Which side are you on?
