As Oil Slick Spreads, German Bank, Unilever Harvest Sun, Wind

Exterior view of the regional headquarters of Unilever in the HafenCity redevelopment in Hamburg, Germany. Perched at the edge of the Elbe River, the striking translucent wrapping cuts frequent wind gusts so that occupants can naturally ventilate their offices. Architect Behnisch Architekten designed terraces that open onto the river. Photographer: Adam Mork via Bloomberg

At the edge of the Elbe River in Hamburg, I approached a seven-story building that appeared to be covered in bubble wrap stretched tight by cables and turnbuckles.

As a great oil slick spreads over the Gulf of Mexico, threatening expanded coastal oil drilling, Germany’s approach to conservation and renewable energy urgently deserves a closer look.

The eye-catching building is the headquarters for the Swiss, German and Austrian operations of Unilever NV, -- the world’s second-largest consumer-goods company, after Procter & Gamble Co.

Architect Stefan Behnisch, of Stuttgart-based Behnisch Architekten, borrowed from sailboat technology as one way to replace mechanical heating and cooling with natural ventilation. His next step was to replace electric lights with daylight.

The Unilever project embodies Germany’s keen focus on conservation and renewable energy.

Unilever’s transparent wrapping is called ETFE, and the yacht hardware holds it in place about a meter outside the building’s glass exterior. It cuts the chill North Sea winds so that occupants can open their windows for ventilation, rather than rely on air conditioning. It also protects external blinds that moderate warm-weather heat and glare.

World Domination

Inside, the office spaces wrap a lively atrium criss-crossed by bridges and stairways, and lined with balconies where marketers and product managers drink coffee while plotting world domination for Wisk.

The area’s big hula-hoop light fixtures are hardly needed since the sun beams through angled skylights overhead. Those fixtures use LEDs, the low-energy light source that is fast vanquishing those dingy compact fluorescents Americans are exhorted to use.

As the heat of people and machines warms the air, it flows naturally into the atrium and up through heat-recovery devices that harvest the warmth and send it back into the building where needed.

The Unilever building requires almost no conventional heating and cooling, which lowers what’s called the primary energy use to 100 kilowatt hours per square meter per year. Remember this mouthful, because it is fast becoming the new lingo of low-energy buildings.

By comparison, an average U.S. commercial building requires about three times that amount.

Frankfurt Bank

In Frankfurt, the KfW bank, established by the U.S. as a development bank to rebuild Germany after World War II, funds green projects nationally and worldwide.

Berlin-based architects Matthias Sauerbruch and Louisa Hutton shaped the building like a plump airplane wing turned on its side. The leading edge points toward the prevailing wind. From that direction, the glass exterior bristles with serrations in a rainbow of colors.

These are flaps that pivot open to harvest breezes. The air flows along the building between the exterior glass and a separate window system inside.

With interior windows that open, the double-layer wall cools in summer and insulates in winter. In any season, the expanses of clear floor-to-ceiling glass light the office space, so electric lights generally aren’t needed.

A geothermal system borrows the earth’s steady temperature for free heating and cooling. This building also aims for consumption of just 100 kilowatt hours per square meter per year.

Skyline Ornament

Did I mention that the 15-story Westarkade is the best thing to happen to Frankfurt’s skyline in years? It glows like a curving, faceted stained-glass window.

Both these buildings go beyond Germany’s stringent existing energy codes, yet they weren’t expensive.

KfW cost 90 million euros ($115 million) for the 39,000-square-meter (421,000-square-foot) building. Unilever leases, but owner/developer Hochtief just sold the 38,000-square meter-building for 101 million euros ($129 million). They sip energy not through wholesale change but by refined deployment of tactics long used in Europe.

The natural ventilation and daylighting are almost unknown in the U.S. because they don’t pencil out in a real-estate development culture of short-term investment horizons, fear of innovation and the presumption that energy will always be cheap.

Germany benefits from refining green technologies and pushing them into the market. Americans are left to pray that global warming is a fraud, energy prices won’t skyrocket, and drilling -- as in the Gulf of Mexico -- will be the answer.

(James S. Russell is Bloomberg’s U.S. architecture critic. The opinions expressed are his own.)

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