The 15-storey glass tower glows with natural light and offers windows that open – thanks to its first-of-a-kind “pressure ring“ faade and sophisticated, sensor-rich control scheme. The building prom…
The 15-storey glass tower glows with natural light and offers windows that open – thanks to its first-of-a-kind “pressure ring“ faade and sophisticated, sensor-rich control scheme. The building promises to consume no more than 100 kilowatt-hours of energy per sq.m. per year – half as much as a conventional office building in Europe and as little as a third of the US average. Horizontal Venetian blinds installed outside of the tower“s glass envelope reject unwanted summer heat, while a pane of glass installed over the blinds and ventilated at the top and bottom protects the blinds from high winds. The “double skin“ design, however, fails when architects add windows that open, typically mandated under European labour codes. Winds create a pressure differential around the tower, sending drafts ripping across floors when workers exercise their right to natural ventilation. Berlin-based Sauerbruch Hutton, the firm that designed the Westarkade, worked with Stuttgart-based firm Transsolar KlimaEngineering to solve this problem, installing 180 vertical ventilation flaps in the outer skin to manage air flows, creating what they call a pressure-ring faade. Thanks to constant feedback supplied from a rooftop weather station and from 40 sensors throughout the building that measure temperature, pressure, and sunlight, the system continually opens and closes individual flaps to maintain a ring of consistent positive pressure around the structure, preventing strong winds from entering. Tthe Westarkade“s high-efficiency heating and cooling systems rely on geothermal heat exchangers, heat captured from a basement data centre, and heat recovered from vented air. In autumn and spring, air from the open windows should eliminate the need for mechanical ventilation altogether. According to Transsolar engineer Bjorn Rohle, his company is confident that the pressure-ring faade is the most efficient means of building windows into a tower. He added that a team at the University of Karlsruhe, in Germany, will monitor the Westarkade“s energy consumption for two years to test whether this approach works. Oregon architect Perepelitza estimates that it will take two years just to tune the Westarkade“s control systems for optimum energy performance. He thinks that this system could point the way forward for glass towers as natural ventilation and energy efficiency grow in importance. This building represents a new generation, Perepelitza says.