Bremen Stephanitorhöfe, Bremen, Germany

Bremen Stephanitorhöfe

Überseestadt is part of the Walle district and is a development area covering about 300 hectares. The former seaport is on its way to become a sustainable and modern urban district. A mixed-use quarter is being created, offering space for living and for commercial services as well as port logistics. New infrastructure for education is envisioned, along with recreational opportunities and appealing public spaces. From the former Kellogg site to the western point of the Überseeinsel, the Stephanitor / Neu Stephani quarter is being created through conversion and new construction. Like all buildings in the district, the Stephanitorhöfe buildings are to become as sustainable and energy efficient as possible and to generate their own energy. In addition, the building is to harmonize with the planned renewable energy supply concept for the entire quarter and ideally act in a grid-serving manner. The living space design is versatile, with wood hybrid ceilings and lightweight walls integrated into a reinforced concrete skeletal frame to achieve flexible apartment typologies ranging from one-room apartments to larger cluster apartments. The office structure is likewise planned to be a hybrid skeletal timber-concrete mixed-use building. Plinths, central staircases and shafts are designed in classic reinforced concrete construction and thus meet the most important requirements such as fire protection, sound insulation and bracing.
Suitable areas on the roofs generate energy with photovoltaics; the electricity generated is used throughout the Überseeinsel via the neighbourhood grid, where it is also used to generate heat and cooling. Rainwater from the roof surfaces is collected decentrally and can be used as garden water. The facades of the upper floors are to be predominantly made of colored pigmented wood and will also show the wooden construction to the outside.
At the beginning of the team's work, Transsolar set up simulations with various parameters and determined the wind and solar exposure of the building design, the daylighting and thermal behavior of selected rooms in the building, as well as the predicted heating, cooling and electricity demand. Previous on-site experience, as well as wind simulations, showed that wind often whistles around the building at high speeds, where it can cause severe drafts. Proposals were developed to mitigate the wind speeds locally. In addition, the wind-loaded façade on the south-south/west arc was identified as the orientation with the highest solar exposure. The existing balconies do not provide adequate shading, and movable blinds would not be functional due to the wind. Therefore, wind-stable shading elements in slat form were developed for these areas, which can be flexibly rotated and adjusted. These allow effective solar shading even at high wind speeds and remain in place when other systems would fail.
Dynamic thermal simulations were used to investigate the potential for thermal load shifting that the building offers to relieve local heating and cooling with heat pumps. It was calculated whether building elements such as the water of the swimming pool or floor ceilings are suitable to absorb excess thermal energy or how the room temperatures would behave if the heating system were temporarily switched off completely.