The Annex 46, within the IEA ECBCS programme, is meant to influence the decision making processin the retrofit of public and governmental buildings that determines the use of energy-saving measures in building retrofits. This decision making process must improve, if it is to successfully cope with the challenges of increasing energy costs and climate change, and if it is to avoid "locking in" long-term commitment to energy inefficiencies by adopting sub-optimal renovations. Consequently, the target group consists of all actors involved in this decision making process, specifically executive decision makers and energy managers of public and government buildings, performance contractors and designers. The purpose of the IT-Toolkit EnERGo, is to support these different user groups, and facilitate communication between them.The IT-Toolkit is an electronic tool assisting in the design of renovations/retrofits focussing on energy savings from the government and public buildings. It consists of a collection of different tools and documents which provide potential lists of solutions to specific energy related problems. It contains descriptions of exemplary retrofit/renovation projects and provides a wide and varied selection of energy conservation measures. The tools contained in the IT-Toolkit allow the user to compare an existing building to the national average or to calculate potential energy savings and costs for a given building.