Turn down or turn off your radiator? The dilemma of winter to reduce your bill

The answer depends on the duration and other parameters, first of all on the insulation of the dwelling.

The duration of the absence

Whether you leave your home for a few hours or a few days, lowering the temperature of your radiator by a handful of degrees is enough. According to Ademe, one degree less "allows consumption to be reduced by 7%". The government has called on the French not to heat themselves above 19°C.

If you are away during the day, you can lower the heating from 19 to 16°C, advises the French agency for ecological transition, Ademe. For several days of absence, you can go down to 14°C. This makes it possible "to avoid too strong a call for power when restarting", explains Cyril Radici, general manager of Synasav, a national union which brings together heating maintenance professionals.

If the absence is to last several weeks, it is advisable to put your radiators in "frost protection" mode, to prevent the accommodation from falling below 8°C.

Today's weather

If it is "a beautiful sunny autumn day", you can completely cut off the heating before restarting it "when you return in the evening", specifies Florence Clément, from Ademe.

But if it's very cold, then you have to keep your radiators running and just turn them down a few degrees, always to avoid a peak in consumption when you start up again.

Regulate and program

For accommodation with individual heating, "the programmable thermostat is essential", explains Ademe. Connected to the boiler, it keeps the home at a constant temperature. There are now programmable thermostats remotely via smartphone. They cost between 60 and 250 euros and allow “up to 15% energy savings”, according to Ademe.

Thermostatic valves can be installed on water radiators to adjust the temperature of each room.

Connected solutions are multiplying. Sowee, an energy supplier subsidiary of EDF, offers a device to adapt its consumption for "up to 25% savings", according to Tiphaine Bougeard, its general manager. For this winter, it is even possible to "delete" from the electricity network by lowering the radiators to "12 degrees for one hour during peak consumption".

In dwellings with collective heating, "it is possible to individualize heating costs in order to pay charges as accurately as possible for consumption", adds Florence Clément, in particular by installing individual thermal energy meters.

Maintain boilers

Maintaining your equipment "is the key", advises Cyril Radici. According to him, 25% of homes are "without a maintenance contract" and a bad boiler setting drives up the bill.

Although electric radiators are less expensive to purchase than a hot water heating system (gas, wood, oil, electric or heat pump boiler), their consumption is higher. Also, hot water heating is "a more interesting investment in the long term", for Cyril Radici.

One solution: insulation

To avoid heat loss, it is advisable to close the shutters at night, to install thick curtains and door bottoms, to close the doors of poorly heated rooms...

The thermal inertia of housing also comes into play: the heavier and denser the building materials (concrete, solid bricks, stone, etc.), the more they absorb and store heat, and can therefore retransmit it gradually. They take time to heat up, but "keep the calories for a long time and release them over several days, limiting heating needs", according to Engie.

But ultimately, "no matter" the inertia and small gestures of individuals. "If the accommodation is poorly insulated", they "will have no impact", insists Florence Clément.

"We don't want to give false hope, eco-gestures are not enough". It is therefore necessary above all to "think about insulation and energy renovation" to "manage this winter but also those to come".