This article presents the findings of a European study on energy efficiency in the public sector, entitled "Public procurement of Energy Saving Technologies in Europe" (PROST), completed in 2003. Energy efficiency in the public sector goes far beyond energy savings and climate protection. Energy efficiency must be seen as a strategy, which deals both with scarce public funds and with profound energy and climate challenges. The gains to be made are substantial. The study assessed the potential for energy and cost savings and the greenhouse gas reductions that are linked to energy efficiency in the European public sector. To the knowledge of the authors, this is the first time such an analysis has been carried out. The study concluded that there are no fundamental legal obstacles that would a priori disable the public sector from procuring energy efficient technologies or applying energy efficiency considerations in its daily building management routines. However, at the level of implementation obstacles can occur. It is therefore of paramount importance that there is sufficient political will and adequate incentive systems at all relevant levels. It appeared to be particularly effective when public procurement is energy-efficiency minded in all its operations and life cycle costing is applied for investments instead of conventional public budgeting procedures. The study demonstrates that consistent and EU-wide application of these principles and instruments can result in rather substantial savings both in terms of energy and in terms of money. With additional annual investments in energy efficiency of 80 million Euro, energy savings in the (EU15) Member States' public sector worth up to 12 billion Euro per year can be achieved. A supplementary analysis was performed for a selection of the new Member States, which indicated that the potential for energy and fiscal savings is substantial in those countries as well. (c) 2004 Published by Elsevier Ltd.