Federal Environment Minister Svenja Schulze (SPD) has given the real estate sector an ultimatum with her climate protection law: Either the CO2 emissions of the buildings are demonstrably falling and there is a risk of government intervention. Specifically, the Climate Protection Act prescribes the building sector to reduce CO2 emissions in fixed annual steps from the current 118 million tons by a good 40 percent to 70 million tons in 2030. If intermediate targets are missed, the responsible ministry has three months according to the law to present an immediate program with which adjustments are made so that the annual sector targets are achieved again in the following year. What exactly such an immediate program could mean for property owners is open. Up to an obligation to replace old oil heating systems, everything is theoretically conceivable.