France’s biggest trade union has called on retail shops and fashion brands to turn their in-store lights off past midnight.

“We have to come to a very strict application of the rule of turning the signs off between 1 a.m. and 6 a.m. and it is compulsory everywhere … and turning down the heating inside by at least 1 degree,” Yohann Petiot, the general manager of the Alliance du Commerce, told FranceInfo news.

The alliance represents 27,000 brands, including popular clothing, footwear and shops in the city center areas across the country.

He said there are ecological and economic imperatives to respond to the government's call for energy sobriety to reduce energy consumption by 10%.

The traders would be more than willing to reduce light and heating rather than being forced to close the stores or face higher electricity bills.

“We have to do everything to limit this impact. These measures on signs, temperature, and lighting, should help to contribute to this,” Petiot said.

Authorities have warned of targeted power cuts in some areas during winter months in case there are problems in electricity production from nuclear energy.

The government has also notified households and businesses to gear up to pay increased energy bills from January 2023.