Building owner: Stäger Immobilien AG
Project: zero emission retrofit
Period: October 2012 – Dezember 2014
Phase: Architecture, Concept, Building, Monitoring
Characteristics: ZERO-Emission Groundwater use
The two-story building is southwest-oriented, with its loading ramp, large ground floor roof overhang, and upper office floor facing Luzernerstrasse. The building’s overall visual impression is completed by its location slightly displaced from the sidewalk. The façade has reached its lifespan, and needs to be renovated due not only to visual but also to structural deficiencies. The windows in particular are in poor condition and the façade’s color has faded due to the effects of the sun.
In order to make the building not only visually but also energetically fit for the 21st century, the renovation of the façade must not restrict the possibility of building use changes in the future. The energy planning of the office spaces and of the production areas are therefore independent from one another. Furthermore, the building’s overall appearance is to be redeveloped in order to make it more attractive for future tenants.
The interior characteristics of the building are also unsatisfactory. A ventilation duct in the window lintel area that is no longer used substantially reduces the daylighting quality. In addition, the windows have a poor g-value, so that the rooms are overheated in spite of the existing external window shading while still using artificial light. Moreover, due to the cold external walls in winter, there is an uneven temperature distribution in the rooms, which creates an uncomfortable perception of space.
Overall, it is clear that the façade and office spaces do not meet the current needs of the building. The building systems are also not up to the current standards.
The characteristic silhouette of the southwest side, with its gabled roof and staircase towers, will be emphasized by extending a second roof overhang along the gable. This measure will stress and add value to the intrinsic character of the industrial building. Furthermore, the existing roof overhang is included in the design in order to create homogeneity between the previous and the planned roof designs. The new, large glass façade responds to and fits between the two canopies. This creates a modern visual perception by simultaneously providing transparency and lightness to the industrial building.
The existing steel construction of the building allows the implementation of prefabricated building components. Steel is a well-known and familiar material for industrial construction. The new building shall maintain this material’s haptics to seamlessly connect old and new. Construction with steel paneling matches the highest demands of modern architecture both in terms of its characteristics and its materiality. In addition, by implementing a sheet metal façade it is possible to work flexibly and stepwise in response to the pre-existing construction.
The goal of the building systems concept was to allow the office and production areas to operate independently. In addition, the office spaces should be flexible and able to react to different demand situations. Furthermore, the offices must comply with modern workplace comfort standards. For this purpose, a building concept was designed to optimize both the façade and the anergetic potential of the area.
Since the use of on-site groundwater was allowed, this efficient anergy source was used both for heating and cooling the offices. A heat pump generates the heating energy for the offices in winter. In summer, the offices are cooled by a free cooling process.
In order to satisfy the comfort standards of a modern office building, the temperature of the in-room building components should always be greater than 18°C for cooling and lower than 30°C for heating. To achieve this, ceiling panels will be installed in the rooms in order to provide large heat exchange surfaces over which the required performance can be delivered.
Providing high quality fresh air requires a ventilation system that is both comfortable and efficient. In order to be flexible to the needs of different activities and users, a decentralized ventilation system will be installed, with individual air supply units located on the building façade. These can be controlled to match the specific demand of each space, so that unused spaces need not be ventilated. Heat recovery from the exhaust air will not be included, since installing the required components is not economically sensible. The higher temperature exhaust air will be used directly in the production area during winter, while during the summer it will be directly released through the roof.
The building façade’s southwest orientation entails high solar irradiation in the offices. While this is a desired characteristic in winter, it also increases the cooling demand during summer. In order to reduce this cooling demand, a roof overhang was conceived and designed to an optimum length in order to minimize cooling demand and maximize solar gains. The U- and g-values of the windows were also adjusted accordingly, while internal shading provides comfort for the workstations.