Every winter, as punctual as the arrival of the cold, the same question comes back: is it better to turn off the radiators at night or leave them on at minimum so as not to waste energy? There are those who swear that closing everything saves money and those who, on the contrary, claim that the house gets too cold and the boiler then consumes more in the morning. But what does science really say?
What the studies reveal: switching off isn’t always worth it
According to research by the United States Department of Energy (Energy.gov), lowering the thermostat by 3–5 °C for about eight hours, for example during the night, allows you to save up to 10% on annual heating consumption.
The reason is simple: when the internal temperature is lower, the house disperses less heat towards the outside. So, even if the boiler has to work a little in the morning to bring the temperature back to comfort levels, the total consumption is still lower than keeping the radiators on all night.
The American document also debunks a very widespread myth:
It is false that the boiler works harder after night cooling, thus canceling out the savings benefits.
In short, there is no need to “fight the cold with a thermostat”: you just need to learn to regulate the temperature intelligently.
Turn down, don’t turn off: the compromise that works
Experts agree: keeping radiators on at minimum is often the best choice.
During the night the ideal temperature is between 16 and 18 °C, sufficient to not let the heat accumulated during the day drop too much.
This approach is particularly effective in homes with poor thermal insulation, where walls and fixtures quickly disperse heat. In these cases, turning off the system completely can cause the temperature to drop by several degrees, making it necessary to make a strong effort on the boiler in the morning.
Those who have programmable thermostatic valves or programmable thermostats can manage everything automatically, setting a gradual lowering during the night and a return to comfort before waking up. This way you get a perfect balance between savings and comfort.
Not just a thermostat: insulation and maintenance matter
Of course, the behavior of the thermostat is not the only factor at play. The level of insulation in your home makes a huge difference.
Thin walls, dated fixtures and poor thermal insulation quickly disperse heat, frustrating any good strategy. On the contrary, a well-insulated home maintains the internal temperature for longer, reducing consumption naturally.
Regular maintenance of the boiler and radiators is also essential: an efficient system works less and consumes less. Finally, it should be remembered that for particular systems such as heat pumps or underfloor heating, Energy.gov suggests avoiding too drastic drops, preferring a constant and moderate temperature.
The real rule for saving? Use common sense
There is no one-size-fits-all magic formula, but the direction is clear:
The “real savings” do not lie in turning off everything, but in knowing how to dose the heat wisely and consistently. Because the cleanest energy is always the one that is not wasted.
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