Energy considerations are often neglected when it comes to refurbishments in office buildings erected in Germany during the first postwar decades. With a primary energy consumption ranging from 200 to 300 kWh/(m 2a), * it is worthwhile thinking about lowering the operating costs for these buildings using ambitious design concepts for their capacity to lower building energy consumption. The German Federal Ministry for Economic Affairs tries to encourage model refurbishments in a funding program called ENOB – ENergy Optimized Building. Within this program, an interdisciplinary planning team developed a concept ready for realization for the office building of the DEGEWO company, located in Berlin (see Figure 1) .
Seventy-five percent of the existing buildings in Germany were built at times when there was no heat protection legislation in force. They account for about 90% of the heating energy demand in the country. Thus, the challenge is to improve the building stock, and this requires a lot more creativity than designing an energy efficient building from scratch .
The funded project of an innovative low energy renovation of an office building is of overriding importance to the planning of similar building types: the single elements of the energy concept and the general principles are transferable and adaptable to almost all office buildings erected in the 1950s, 1960s, and 1970s. The experiences and findings of the planning concept can be utilized independently of the specific project.
This paper first describes the energy concept and its components as a result of an integral planning approach. In its second part, the application of dynamic building simulations as a powerful analysis tool during the conceptual phase of this project is demonstrated. The design team is introduced in section 3.