“…this could result in savings of more than 380 million euros by German households (or 1.8 billion euros if all European households were to lower the room temperature by 2°C)” https://arxiv.org/ftp/arxiv/papers/2203/2203.02756.pdf
Lowering room temperature in European households is of course an interesting idea but that does not work for the many millions that already live in energy poverty (Mapping energy poverty in the EU: policies, metrics and data). Moreover, 1.8 billion will have a minor impact on Russian energy exports that reached almost 500 billion in 2021.
A much more effective measure is the long term energy agreement that Germany seal today with Qatar https://english.almayadeen.net/news/economics/germany-and-qatar-agree-on-long-term-energy-partnership
PS – Some famous academics also came up with a good idea, they advise that the European Union must set up a task force to seize all Russian assets located in offshores in the paper “Effective sanctions against oligarchs and the role of a European Asset Registry” like they just did in the USA with the creation of the Task Force Kleptocapture. https://www.justice.gov/opa/pr/attorney-general-merrick-b-garland-announces-launch-task-force-kleptocapture