Ecological construction that not only adorns itself with the label, but actually implements sustainability holistically at all levels, is regarded as the future of construction. The 42! project in Bonn's Weststadt district - a student residence designed and realized by the raum für architektur office from Wachtberg for a private client at a low budget of less than €1,500/m² - is a best-practice example of how this does not necessarily have to be accompanied by horrendous construction costs. The design concept is characterized by a holistic architectural approach: the optimized building envelope alone was intended to reduce the technical requirements for heating, ventilation and cooling to a necessary minimum. At the same time, building materials were to be used that could be separated by type at the end of their life cycle and easily returned to the circular economy.

The five-storey building with 32 one- to two-room apartments fills a former gap in the building stock. With the exception of the central staircase, all exterior and interior walls were built using an ecological timber frame construction method with wood from sustainable regional forestry. The side firewalls to the neighboring houses were also realized as solid wood walls - a German first. Finally, cellulose insulation made from recycled newspaper was blown into the entire skeleton and the raftered roof. The timber-concrete composite floor slabs are acoustically optimized. The façade was designed with photocatalytic and therefore self-cleaning wood fiber concrete panels, whereby the panels of the photovoltaic system could be integrated at the same time. The materials used in the interior fittings were also selected not only according to aesthetic criteria, but also recycling criteria. The dimensions of the building services system were surprisingly minimal: A micro heat pump of 2.3 kW - an output equivalent to that of an electric hairdryer! - was combined with a central ventilation system with heat recovery, which enables up to 84% of the heat consumed to be reused. It is powered solely by the photovoltaic system and a battery storage unit, which supplies the house with general and household electricity all year round. Rainwater is also collected and reused for flushing the toilet. To ensure that the KfW 40 Plus Passive House runs smoothly even at peak times, there is a smart home control system that analyzes the residents' ventilation habits, among other things, and provides users with direct feedback on optimization potential. The result is a well-coordinated system that combines efficiency and sustainability in a very practical way.

www.raum-fuer-architektur.de

Photos:

Ives Paduch

(Published in CUBE Cologne Bonn 03|21)