Berlin's old building structure, with its possibility of roof extensions and storeys, contributes significantly to urban densification and the creation of urgently needed spaces that enrich the city in the juxtaposition between old and new.
The project Friedrichstraße 124 is part of an old urban development plot, originating around 1880, and is located at the northern entrance to Friedrichstraße in Berlin-Mitte.
The plot is 50 m deep and 12.50 m wide and has a lot of potential for expansion with its existing building volume that steps down towards the rear.
The existing office buildings were extended by up to two storeys using timber frame construction. This generated and activated approx. 40% additional office space.
Due to the tight space conditions on site and the overhead lines for the tram running in front of the building, a crane position for the delivery of the building materials was impossible.
To realise the extensions, a light, elemental timber construction was chosen that made it possible to transport small elements by using a freight lift.
The load-bearing capacity of the existing building structure allows a limited additional static load. In timber construction, the extension by several storeys is possible due to the light construction method.
The roof was designed as a diagonal plane structure in order to bear the loads of the technical equipment above.
This diagonal structure gives all the newly added parts of the building a distinctive new character.
The expansive view that can be enjoyed over Berlin from the top floor is in strong contrast to the ground floor zone, which is surrounded by high fire walls and which at the same time covers the entire 50-metre depth of the site.
A cathedral-like, 9m-high structure at the rear of the site not only creates an impressive spatial experience, but also reflects sunlight into the courtyard via the metal façade, creating new qualities of stay.
The entire courtyard is transformed into a country garden that places themes such as agricultural crops, water conservation and rural atmosphere in the immediate urban context.
Cisterns collect the water from all roof surfaces to water the garden.
In order to move away from fossil energy supply, the energy source was realised by an air-source heat pump.
The ventilation systems are equipped with heat recovery. The exhaust air from the rooms is passed through a heat exchanger. The fresh air is thus heated or precooled.
A densification of existing building structures in Berlin's city centre is easily possible due to the lightweight timber frame construction. Thus, between 35-45% additional space can be generated and activated through undeveloped roof spaces.
An energy reorientation of the buildings, some of which are still heated with coal, has been tested and can be realised using highly efficient heat pumps and heat recovery systems. In this way, a large part of the building stock can be brought up to a sustainable energy standard.
Rainwater can be collected and made available for personal use.
