The EU energy efficiency directive (EED) includes provisions to stimulate increased energy efficiency in companies. Mandatory provisions were first introduced in 2012 and recast in 2023. Policy learning has been suggested as an important route to policy change. This paper analyses how and why policy learning helped revising EU legislation to enhance energy efficiency in companies, using provisions of mandatory energy audits as a case. Negative experience from member states’ governments with the original provisions were voiced shortly after the adoption of EED. A complex process going back and forth between member state and EU levels led by a learning agent facilitated collective learning and change of beliefs, first in member states then in the Council. Several cognitive biases among individuals in the European Commission led to non-learning at the individual level and blocked learning at the collective level. This further blocked policy learning in the EU when EED was amended in 2018. However, external crises and the entering office of a new Commission College in 2019 made the Commission to reconsider its beliefs. Political leadership opened a window for individual and collective learning in the Commission and policy learning in the EU when provisions were changed with the recast of EED in 2023. This suggests that individual and collective learning in the EC is key for policy change to happen. Without new beliefs in the EC, it is hard to get a topic onto the policy agenda. The paper proposes policy recommendations on how to facilitate policy learning and suggests areas for further research.