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The size of the office building's window surfaces provides an optimal level of daylight with the lowest solar loads possible. The ventilation system's suction towers are seen the foreground.
© Software AG Stiftung
New office building in Ulm reaches passive house standard
Projektinfo 05/2006
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Office comfort with regenerative cooling

The EU directive on the energy performance of buildings requires a broad perspective when conducting energy assessments of non-residential buildings. Now for the first time, the total energy required for operating the building is included in the calculations, unlike earlier, when only the heating requirements were considered. The German Federal Ministry of Economics and Technology (BMWi) has already been taking this approach for several years in its support initiative Energy-Optimised Construction (EnOB).

The demonstration projects (new non-residential buildings) as part of EnBau, a branch of this initiative, were designed to achieve a primary energy requirement for heating, cooling, ventilation and lighting of less than 100 kWh/m² p.a. One implementation possibility is to take the passive house concept (now proven in residential buildings) and apply it to other building types, interpreted according to requirements. The premise of very good thermal insulation, air tightness, and ventilation with heat recovery is also a very good basis for ensuring overheating protection in summer, which is often critical for office buildings. This possibility was also chosen by the Software AG Foundation as investor in the construction of a new office building in Ulm, Germany. As this foundation promotes, among other things, measures which "help nature", ecological objectives were also foremost while making a valuable real estate investment. Thus, from the onset, the passive house standard was called for in a limited-invitation competition for planning teams. High comfort and an up-market atmosphere with economical construction methods were additional requirements.


With 8,000 m² gross floor area, this passive house office building is as yet unique in its size. As a very compact building form was chosen, the planners had more scope for optimisation. It was possible to dimension the windows regardless of orientation. Furthermore, it was not necessary for all of the utilised building elements to satisfy the highest thermal standard in order to meet the requirements overall. A comfortable interior climate is achieved with the implemented design by means of high quality thermal insulation, concrete core temperature control, mechanical ventilation, and flexible sun protection. The use of renewable energy sources lowers the primary energy requirement. The integral planning of architecture, construction physics, and building services equipment in a project team of experienced partners, the implementation of proven components and construction materials, as well as diligent quality assurance, were decisive factors in the success of this ambitious project. The building was finished in October 2002. The analysis of the subsequent measurement phase is now available.

Projektinfo 05/2006:
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