Brattørkaia is an eight-story office building that will produce 485,000 kilowatt hours (kWh) annually. For reference, the average Norwegian home uses about 20,000 kWh of power a year. (In the United States, the yearly household average is 10,399 kWh). Brattørkaia will, in effect, become a mini power plant that can supply electricity to Norway’s publicly owned grid.
Its surplus energy will also compensate for the power used to produce its building materials. That, says the Snøhetta architect Jette Hopp, is unique; prevailing definitions for energy-positive buildings don’t include materials’ embodied energy.
Hopp says accounting for that energy makes for a more complex development process. Recycled materials are favored above all. New materials are diligently traced. The design process is front-loaded with engineering expertise. Alliance members work together to make sure every design choice has a dual purpose. “Nothing is by coincidence,” Hopp says. “We try to give things multiple functions, and that directly leads to less embodied energy since we don’t have to double or triple up systems. That’s in the smart thinking—but you need to have the knowledge of all the different layers of infrastructure works in order to find synergies.”
That meticulousness is apparent at Powerhouse Kjørbo. The retrofit project, composed of four short office buildings in a business park outside of Oslo, was the first to be completed by the collective. During September’s Oslo Innovation Week, Bernhard, of Asplan Viak—whose offices are located at Kjørbo—gave a detailed tour of one of the buildings.
Motion sensors click lights on and off as people move about the building. An internal spiral staircase doubles as a ventilation shaft. Rooftop solar panels collect energy on bright days, energy wells store it, and geothermal power compensates on colder, grayer days. (Track Kjørbo’s performance here.)
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The building’s concrete frame was recycled, and the old exterior glass windows were reused to make interior partitions, which help maximize daylight. Additional insulation panels were made from old plastic bottles. Rather than use energy-intensive metal, a Japanese wood-burning technique called shou sugi ban was used to blacken Kjørbo’s new facade.
Prior to refurbishment, the building consumed an average of 250 kWh per square meter, Bernhard says. “That has been reduced by 85 percent,” he added. Kjørbo’s excess energy is used to heat another building and to power a nearby hydrogen-car refueling station.
The hope is to make energy-positive neighborhoods next, Bernhard says.
Energy-positive construction has piqued other countries’ curiosity—particularly Germany’s—but it still hasn’t had its breakthrough moment. Hopp says that, so far, all of Powerhouse’s requests have come from inside Norway.