The objective of the project was to demonstrate the potentials of a retrofitting process for a typical school in West-Germany from an energy point of view. The block of buildings that was renovated was a primary school in the city of Stuttgart, built in several segments during the thirties, the fifties and the seventies. Supervised by Stuttgart's municipal office of environmental protection, the Fraunhofer-Institut für Bauphysik (IBP) and the Institut für Kernenergie und Energiesysteme (IKE) worked out an action plan from an energy point of view. In this process the municipal office for construction, the architect, engineers and our project partners from industry were involved. The design phase was completed during spring 1996. An architect together with an HVAC-engineer planned and realised the retrofitting, supervised by the municipal office for construction. The work in the school buildings started in the summer break 1996 and finished summer break 1997. After the realization phase a two-year period of measuring the actual energy consumption gave proof of the concept.