French shops will have to close their doors when using air conditioning under a ruling designed to cut energy use.
The rules are soon to be rolled out across France, with some areas already having adopted the policy drawn up by minister Agnès Pannier-Runacher.
Shops will be fined up to €750 (£640) for breaking the rule, as France looks to tighten its energy usage due to pressures resulting from increased costs after Russia invaded Ukraine.
Ms Pannier-Runacher told RMC radio that it is “absurd” that shops would leave the air-con on and open their doors.
She told the Journal du Dimanche newspaper: “(We will) ban shops from having their doors open while the air conditioning and heating are working."
She added that “there will (also) be a ban on illuminated advertising, whatever the size of the city,” between 1am and 6am - which is already in place for smaller places. Airports and stations will be exempt.
The news comes as Shell released a warning that rationing of power supplies cannot be ruled out.
Much of Europe is continuing to feel extreme heat this week following widespread wildfires.