Low Energy Office: Design and Evaluation

Abstract

The new government building with ca. 14.000 m2 gross floor area in Innsbruck/Tirol was designed as a low energy office building. As little technical installations as possible and as much room comfort as achievable: These were the two goals, set by the builder and user. An interdisciplinary team of architects, HVAC-planners and energy designers had already developed an integrated concept for the architectural competition. This was altered and adapted during the realization phase of the building. Detailed building simulations were used to determine the interactions of building, climate and users. The integration of three glass atria into the concept, unheated and naturally ventilated, was one of the main challenges in this planning process. These atria serve as thermal buffers and use the passive gains of solar energy. Only the internal areas are ventilated mechanically. The facades were optimized to combine daylighting and protection against high solar irradiation. Reduction of the cooling load, night ventilation of the atria and groundwater cooling in the offices secure moderate temperatures without any mechanical cooling. Despite a dense utilization the building offers attractive workplaces with a comfortable room climate. The energy consumption for heating in the first fully measured year was 35 kWh/m2, which is very close to the prediction. The consumption of primary energy is low also. The measured atria air temperatures comply in general with the simulated ones. A direct comparison of simulation and measurement is planned for the future.