Net Zero

The world’s largest color LED display gets its power—and symbolism—from photovoltaic cells embedded in a glass curtain wall.

Digital media displays are all about spectacle, and the new GreenPix wall, in Beijing, is no excep­tion. Indeed, it is the largest color LED display in the world, with 2,292 of the energy-efficient lights spanning a 24,000-square-foot glass surface. In the evening, as traffic throngs the busy road it faces, the wall plays massive low-resolution video installa­tions by Chinese, Japanese, European, and Amer­ican artists.

But GreenPix is also a fairly radical example of sustainable technology. Simone Giostra and Part­ners, working with Arup and German manufacturers Schüco and Sunways, laminated photovoltaic (PV) cells inside the glass curtain wall. In itself this is not new, but the level of integration and the scale of GreenPix are unique. The 6,000 square feet of PV cells are arranged with varying density: where nat­ural light is needed inside the building, there are few or no cells; in other places, dense as­sort­ments of cells block the sunlight, reducing interior heat gain while generating enough electricity each day to power the display at night.

“It’s more symbolic than pragmatic,” Giostra says. “Of course, we could use the energy for more useful systems of the building. But we decided that perhaps it is more important to give an ethical sense to the project—that it is truly independent and self-supporting.” This also means that the system is vulnerable to outside conditions. If there is not enough sunlight during the day, evening performances will be shorter or the lights dimmer. That may cut back on the spectacle, but it does nothing to diminish the symbolism.


Polycrystalline photovoltaic cells laminated within a glass curtain wall

The photovoltaic cells block solar heat gain where needed and generate enough electri­c­ity to power an LED display.

Strategically embedding photovoltaics in glass allows buildings to squeeze extra electricity out of daylight.


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