A GOOD CLIMATE FROM DAY ONE

From day one, the creators of the Potsdamer Platz quarter had an eye on the environment and the tenants’ quality of life – hence planning started well in advance.

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View onto Piano-See at Reichpietschufer

The Potsdamer Platz quarter stands on solid ground – and it thus inherited a well-known challenge in urban planning: soil sealing. There are not a whole lot of options for rainwater to escape. Where to with the moisture from above then?, the creators of Potsdamer Platz contemplated. Their answer: keep it! Thus, the idea of one of the most modern concepts for sustainable management of water in the city was born.

Let’s start at the top: the roofs of the quarter are extensively landscaped. Blossoms extend over an area of 16,300 m2 – no fertilizer, no chemicals – on glass, gravel, metal and bituminous surfaces. Downpipes collect and distribute the water. On average, 20 percent of the annual rainwater is reused for urban waters, irrigation of plants or in toilets. The remaining 80 percent is used for roof landscaping; or the water evaporates and thus plays its part in improving the quarter’s climate.

Once the rain arrives at the bottom, Gerd Daugardt from Wisag company takes over. Daugardt is the technical operator of the urban waters and is a busy man: even before the water fills the three lakes of Potsdamer Platz – the large triangular lake, the south pond and the water features near the piazza at the casino – it travels through a gravel filter. Here, the “raw water”, as Daugardt terms it, is pre-filtered. The result: “non-potable water”. It then reaches five underground cisterns and a reservoir with a total volume of 2,600 m3.

ALWAYS IN MOTION

From here, a more complex apparatus takes up its work: 18 pumps move the water up to the toilets, the greenery in the quarter and finally the lakes. In summer, the three bodies of water cool down the air by two to three degrees. It provides for a breezier, more pleasant and healthy environment in the quarter as compared to many other urban centres in the capital.

Infografik: Bente Schipp
ecosystem at Potsdamer Platz (Infographic: Bente Schipp)

The computer-controlled pumps circulate the water to ensure the required oxygen levels are achieved and to prevent pollution. At the same time, the water motions constitute a true design asset effortlessly: the interplay of light and wind transform the patterns created by flow obstacles, such as the undulating steps at Marlene-Dietrich-Platz and thus help shape the unique aesthetics of the quarter.

Despite the water’s ability to self-purify, it needs some support. Gerd Daugardt checks the oxygen levels, turbidity, and temperature of the urban waters on a daily basis. If required, he plugs in micro-screening equipment, which filters algae and suspended solids from the water. These sediments are collected in a drainage basin, which is cleaned regularly.

In this sophisticated system, difficulties rarely arise. Merely straws that are tossed into the urban waters by visitors pose a challenge. “Although they are thin, they are long enough to get stuck in the pumps”, Daugardt explains. Fish, on the other hand, do not cause any trouble. On the contrary: they contribute to the biological purification of the water. Recently, he even discovered a turtle. “But how it got into the lake remains a mystery.”

Gabriele von Kardorff has never had to deal with turtles. A civil engineer by profession, she was mainly involved in the overall eco-management during the planning and construction phase of the Potsdamer Platz quarter as a construction biologist with Drees & Sommer. The water concept, including the roofscape and the restraint system, was her idea. Today, she manages the planning office Kardorff Ingenieure Lichtplanung GmbH. Still, she remains proud of her concept for the quarter to this day – especially because it has been implemented step by step over a period of nine years. From the start, von Kardorff had pushed for an energy source using district cooling rather than individual plants, thus laying the most important groundwork for the eco-management.

A NATURAL CLIMATE

Also the 19 buildings in the quarter are optimised in their energy consumption. As a rule, sky-scrapers do not have windows that open on the top floors – not so in the Potsdamer Platz quarter. The double-skin facade in Eichhornstraße 3, for example, sets technical standards. Using elaborate model tests, von Kardorff and her team calculated that an outer, transparent facade with lamellar openings reduces the wind pressure considerably while simultaneously serving as ventilation, without causing papers to blow off of a desk. In winter, it makes use of the passive solar radiation. An energy-optimised indoor climate is created – supported by mechanical ventilation only if desired.

The building supplies that have been tested for harmful substances constitute another important factor for the indoor climate. All varnishes, paints, insulating materials and floor coverings have had to meet the strict criteria set by von Kardorff. “No tender specification or construction contract went out, without us having checked it first”, she remembers. Indoor air tests still yield top results. The construction manager’s manual is legendary, having motivated more than 200 construction firms involved to meet ecological requirements from the shell to the interior design.

The result is astounding: a carbon dioxide emission that is 70% lower as compared to a conventional energy supply, a pollution free habitat and foregoing air conditioning systems, and it continues to generate attention and recognition worldwide not just amongst architects. In 2011, the Potsdamer Platz quarter received the Certificate in Silver from the German Sustainable Building Council – 20 years after planning had started at that.

Text: Bernd Ratmeyer
Photos: Vincent Mosch
Infographic: Bente Schipp

 

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