It has become a big joke on national radio but it might just help France’s energy problem this winter—the government is advocating everyone wear turtle necks to keep warm and reduce energy consumption.

President Macron and his cabinet ministers have now ditched suits and ties and are appearing on television and at press conferences in turtlenecks. Of course, it’s just very public marketing for what is a very big plan—it is being called the winter of Energy Sobriety.

Everyone is being encouraged to save energy as part of the French government’s massive and not-inconsiderable plan to reduce France’s energy consumption by 10% in two years, and ultimately by 40% by 2050.

The government owns nearly a third of all buildings across France (including museums, the central bank, government offices, etc.) and so has turned its attentions inwards—Stanislas Guerini, the minister of transformation and public functions, said Thursday that these buildings use the same amount of energy as metropolitan Paris. That’s 20 terawatts of power. The state plans to reduce its power usage by 2 terawatts this winter, equivalent to a small city.

As part of its plan, temperatures are not allowed to exceed 19 degrees in government buildings and hot water will be unavailable, and public officials will need to take the train or drive more slowly to conserve fuel—not above 110 kilometers per hour (68 m.p.h.) instead of 130. Government workers will receive 2.88 euros ($2.86) per day if they work from home and businesses are being encouraged to do the same.

The Eiffel tower is going dark earlier, as its lights will be turned off at 10:45 pm, (instead of 1 am), and most streetlights in smaller cities will also be turned off in the early hours of the morning (Paris’ mayor, Anne Hidalgo has said she will keep the capital alight all through the night for safety). Illuminated ads will not be allowed to run at night and businesses will have to turn off lights. The water in swimming pools will be one degree lower across the country.

The hope is to wean the country off gas supplies that have become increasingly uncertain since Russia’s invasion of Ukraine. President Emmanuel Macron told business leaders that “if we all mobilise to meet this objective, we will get through the winter even in the most unfavourable scenarios.”