With the support of the European “THERMIE – Energy Comfort 2000” programme, an ecologically friendly office building was to be created with a low energy balance and requiring a minimum of maintenance. Solutions were found that reduced the energy consumption to about 50 per cent of that for comparable buildings. A major aspect of the design was the sunshading of the exposed east face, where the main functional spaces are located. This facade is in a two-layer form of construction. The vertical glazed elements forming the outer skin are adjusted automatically according to external temperatures and the position of the sun and can ensure up to 70 per cent shading. Additional horizontal shading is provided by the maintenance walkways between the facade layers. The decisive factor in determining the size of the standard offices (7 x 3 m) was an optimum exploitation of daylight. The offices are divided by glazed partitions or free-standing furnishings. This ensures better air circulation as well as a sense of openness and transparency. The thermal mass of the extensive concrete coffered ceilings is exploited to reduce overheating. Ventilation openings in the facades are linked to the voids in the hollow floors and serve to cool the offices at night. Individually adjustable internal sunblinds and ceiling fans, together with cross-ventilation, mean that the air-conditioning has only a supporting function in many cases. The technical services are largely controlled by a special computer system.