This Leonardo ENERGY study shows a vast energy saving potential for the European building stock, by increasing the adoption and installation of Building Automation Technologies (BAT) and Building/Home Energy Management Systems (HEMS/BEMS). Compared with a reference scenario which assumes a continuation of current trends in the adoption and installation of BAT and BEMS/HEMS, the optimal scenario estimates the savings to reach 22% of all building energy consumption by 2028 and maintain that level thereafter. Impressive as the saving potentials are, they will not be realized without measures to stimulate both good practice and higher rates of deployment. The report has identified a range of complementary measures and recommended actions.