The National Efficiency Label for old heating systems is intended to inform consumers about the efficiency status of their old heating systems. The Federal Government's aim is to increase the replacement rate of old inefficient systems in this way and thus ultimately save energy. While efficiency labels are established for many types of new products, the National Efficiency Label for Old Heating Systems has been issued for the first time for existing systems since 2016. The IZT and the Öko-Institut evaluated the National Efficiency Label for old heating systems in terms of target achievement, effects and cost-effectiveness. The evaluation took place ex ante, concurrently and ex post.