People in Germany have to save at least 20% of their energy consumption to avoid a gas shortage by December due to falling Russian gas flows, Germany’s network regulator head Klaus Mueller said.

Russia’s Gazprom has cut gas flows to Germany through the Nord Stream 1 pipeline to 20% of capacity, raising pressure on Europe’s biggest economy to save gas for winter.

Mueller said Germany should also cut its gas exports to neighboring countries by 20%, and import 10 to 15 gigawatt hours (Gwh)of gas to avoid shortages.

“If we don’t save a lot and don’t get any additional gas, we’ll have a problem,” Mueller said in an interview with Welt am Sonntag newspaper published on Aug. 6.

Germany last month raised its storage targets for autumn to 75% by Sept. 1, 85% by Oct. 1 and 95% by Nov. 1, and had introduced save energy measures.

According to the government’s gas emergency plan, private households will be prioritized in case of a gas supply crunch but Mueller said the prioritization doesn’t mean that households can heat excessively in that situation.

“In order to secure jobs, I think austerity measures for private households are legitimate,” Mueller added.

Securing gas through fracking in Germany, as some regional politicians have been demanding, will not solve the gas shortage problem in the coming two winters in which Berlin will still be dependent on Russian gas, he said.

But Mueller declined to say whether a life extension of Germany’s remaining nuclear power plants was conceivable, referring to the awaited results of a stress test the government is conducting to answer that question.