Physics is clear that it is a mistake

In the middle of winter, a classic dilemma always returns in Spanish homes: is it advisable to leave the heating on all day to avoid the “peak of consumption” when turning it back on or is it better to turn it off every time we go out? For years, fear of an astronomical bill has fueled the myth that “keeping warm” is cheaper. But this winter, experts have decided to settle the issue by relying on an unbeatable ally: the laws of physics.

The five minute rule. For Jorge Morales de Labra, industrial engineer and energy analyst, the answer does not allow nuances. As explained in Cadena CopeTurning off the heating is always worth it. In fact, he exemplifies it very simply: “Even if you go down for five minutes to buy bread, it is economically worthwhile to turn it off.”

This statement has a solid scientific basis. As Morales de Labra details, heating systems consume energy constantly to compensate for the heat losses that the home suffers through walls, ceilings and windows. If the heating remains on while no one is there, we are paying for a comfort that no one enjoys, forcing the boiler to work tirelessly to counteract the cold outside.

So why does shutting down save more than maintaining? The key lies in demystifying the “effort” that the boiler makes when starting. Although it is true that the boiler works more intensely to recover the initial temperature, this specific consumption is much lower than the sustained expenditure to keep the system running during hours of absence.

Furthermore, the figures support this thesis. According to data from the OCU (Organization of Consumers and Users)If we decide to turn off the heating completely at night, the savings can skyrocket up to 67%. For their part, energy efficiency studies cited by El Español They estimate that by simply turning off the system for short and moderate absences, a family can reduce their annual bill by 8% to 15%. In an average home, this represents a direct saving of between 50 and 120 euros per year.

The “invisible limit” of 21 degrees. Another common mistake is to confuse comfort with excess heat. The Institute for Energy Diversification and Saving (IDAE) warns that Each degree we go above that threshold makes the bill 7% more expensive. The official recommendation is clear:

• During the day: Between 19 °C and 21 °C is the optimal temperature.
• At night: Simply keep it between 15°C and 17°C, or turn it off directly.

It should be remembered that this rule is universal for radiators and heat pumps. Nevertheless, systems such as underfloor heatingwhich have great thermal inertia and take hours to heat up, require more stable management and do not benefit from shutdowns lasting just minutes.

The crucial role of insulation. It’s not all the thermostat’s fault; The reality is that almost half of what we pay depends on the walls. If your house has leaks, heat literally escapes through the cracks, forcing you to turn up the heat to avoid shivering. It is a vicious circle that empties the pocket. Luckily, the International Energy Agency (IEA) suggests several effective patches that do not require getting into work:

• Seal drafts: Installing weather stripping on doors and windows can save up to 100 euros annually.
• Blind management: Open them during the day to take advantage of the sun and close them tightly at nightfall to add an extra layer of insulation.
• Adjust the boiler: It is recommended to lower the boiler delivery temperature (the water that goes to the radiators) to improve the efficiency of the equipment.
• Smart ventilation: Simply open the windows for a few minutes in the morning to renew the air without the walls getting cold.

An investment in control. Savings do not come from being cold, but from managing the heat intelligently. Jorge Morales de Labra emphasizes the importance of smart thermostats. These devices allow programming the heating so that it turns on half an hour before we get home or turn it off from our cell phone if we have forgotten.

In short, this winter science gives us permission to turn off the switch. Heating an empty house is not comfort, it is waste. True efficiency is not about generating more heat, but about preventing the heat we have already paid for from escaping.

Image | freepik

Xataka | Heating has an invisible limit: going over that temperature raises the bill without you noticing more heat