Potential gains from improving energy efficiency are substantial — not only in terms of saving energy and combating climate change, but also in terms of contributing to an array of other co-benefits, including improving human health and creating jobs. We asked Tim Farrell, Senior Advisor at the Copenhagen Centre on Energy Efficiency, what works best when it comes to boosting energy efficiency. He stressed that targeted policy measures and sufficient resources to support implementation and compliance are among a number of critical ingredients for success.