A Berlin park atop an office building offers a new model of urban landscaping

Berlin is a green city, with the Tiergarten at its heart and a necklace of forests and lakes. Still, a public park atop a new office building is a new model of urban landscaping for the German capital. Named Darwinstrasse 1 for its street address in the Charlottenberg district, this is an eight-storey linear block – the first to be built on a former industrial site beside the River Spree.

Designed by the prolific Berlin firm Grüntuch Ernst Architeken, it applies the sustainable architecture principles laid out in Hortitecture, a book that includes contributions made by 33 architects at a series of symposia on the synergy of architecture and plantings, and how that enhances the environment.

Discover Darwinstrasse, an elevated, new Berlin park

As GEA observes in its introduction, 'unlike solid building materials, which are fixed and controlled by the architect, living green materials challenge the design with the dynamics of growth'. It’s a challenge GEA has mastered in several other commercial projects and schools, and in Berlin’s Wilmina Hotel, which the firm created within a former women’s prison.

The commission for Darwinstrasse 1 came from Bauwens Development, a Cologne-based firm, who responded enthusiastically to the planners’ mandate for a publicly accessible roof garden that would create a valuable amenity for tenants and the neighbourhood. An open staircase runs up the west side of the 120m-long block to the north end of the fourth floor and the 2,200 sq m park cascades down from the south end. Trees in planters 2m deep rise from each terrace.

Ingenhoven Architeken’s Marina One complex employs a similar strategy in Singapore, where every new commercial development has to devote 25 per cent of the site to green space that is open to the public 24/7. In Berlin, where innovation is often stifled by a forest of regulations, it is a new departure that deserves to be widely copied, just as the Viaduc des Arts in Paris and New York’s High Line have inspired planners around the world.

Inevitably, the park and staircase added to the complexity and cost of construction. 'We were lucky to have a client willing to pay for that,' says GEA co-principal Armand Grüntuch.

For the architects, a major challenge was to reinforce the roofs to sustain the weight of wet earth 40-150cm deep and create a waterproof seal. They specified a concrete with embedded carbon and the building utilises renewable energy from the neighbouring power station. The open-plan floors are lit from expansive windows that can be shaded by external blinds. The spaces have an open technical infrastructure in the ceilings and they can be easily reconfigured with soundproofed partitions to accommodate a thousand workstations.

A large Bavarian investment firm bought Darwinstrasse 1 and is now leasing it to other firms. The landscaping will continue to grow but already it has created a significant micro-climate, with a measurable difference of temperature between park and street. Multiply that ten thousand times and Berlin would be the greenest city in Europe.

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