Powerhouse building produces more energy than it needs

Photos by Ivar Kvaal. Courtesy Snøhetta.

Last year, the City of Vancouver updated its green buildings regulations to require that all re-zoning applications meet either net zero or low-emissions standards, considered among the most stringent in Canada. The move, combined with incentives, has helped trigger a boom in the development of so-called “passive house” projects that use extremely low quantities of energy for heating and cooling.

If these shifts mark the state of art as Canada slowly wakes up to the implications of the climate crisis, consider a recently opened 200,000 sq.-ft office building project by Snøhetta in Trondheim, Norway, a remote northern city at the same latitude as Yellowknife. The Powerhouse Brattørkaia isn’t merely a net zero building; this structure actually produces surplus clean energy (all of it solar) that is pressed into service in a micro-grid serving the surrounding community.

As Snohetta founder Kjetil Trædal Thorsen said of the project, “Energy-positive buildings are the buildings of the future. The mantra of the design industry should not be ‘form follows function’ but ‘form follows environment.’”

The sleek, wedge-shaped building overlooks Trondheim’s harbour and features a distinctively angled pentagon-shaped roof plane interrupted by a circular opening. According to senior architect Andreas Joyce Nygaard, the angle of the roof is optimized to harvest solar energy, which is tricky in northern Norway, where the sun can be very low on the horizon in the winter and very high in the summer. The 21,500 sq.-ft roof produces 25% of the building’s energy needs, with the balance provided by more PV panels on the walls and a deep-water heating/cooling system.

But Nygaard points out that the Powerhouse was designed with a holistic view of energy that incorporates not only the building’s current consumption but also the embedded energy in the materials as well as their capacity to be re-used at the end of a 60-year life cycle. The glazing, for example, varies depending on the orientation of the windows to the sun so they provide the maximum amount of daylight to replace or augment artificial sources. The windows facing the sun (south and west) are smaller because, as he says, cooling the building takes a lot more energy than heating does, thanks to the extensive insulation used in the design.

The exterior cladding is a very thin, dark aluminum sourced from a supplier that uses recycled aluminum in its production, thereby minimizing embedded energy and carbon. The aluminum closely resembles the wall-mounted solar panels. “It has to have an aesthetic,” says Nygaard.

© Synlig.no

The building’s energy system includes “liquid light” – an interior lighting system programmed to adjust to the amount of available daylight – and a computer-operated network of windows and shades that open and close automatically as a means of maintaining fresh airflow instead of forced air.

Nygaard acknowledges that the Powerhouse’s performance depends on both its orientation and the absence of shadows from nearby buildings. He also says Powerhouse tends to generate surplus energy during the summer months, when energy is cheap and plentiful, but still draws on local power sources in the winter. “It’s not like we’re independent. We need to be connected to the grid.”

The next challenge for Snohetta’s powerhouse concept is figuring out how to store the surplus energy produced during the summer months, potentially in on-site energy storage devices like batteries. “At this point, there’s no solution for that,” Nygaard says. “If we have one, maybe we could be off the grid.”

Toronto journalist John Lorinc writes about cities, sustainability and business.



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