As just about every building type has been pushed toward greater energy efficiency, airports have been something of a stubborn holdout, relics of a more consumptive era. In Oslo, though, a new expansion to the city’s existing airport provides another, more sustainable way of designing these structures. There, the Oslo-based firm Nordic—Office of Architecture has just cut the ribbon on what has been called the world’s greenest airport. The expansion, which doubled the airport’s size, earned an “Excellent” rating in BREEAM (Building Research Establishment Environmental Assessment Method, roughly comparable to LEED), and it was the first airport to earn such a designation. Energy consumption in the expansion has been cut by more than 50% of those in the original, bringing the new terminal to energy consumption levels comparable to a Passive House project.

To make this building perform so well, Nordic subjected every design decision to a careful environmental assessment. As Gudmund Stokke, the firm’s principal partner and chairman put it in a conversation with AD , “in every respect, we took a strong approach to the environment.”

Those decisions started with the form and orientation of the terminal itself. In many airports, soaring glass walls make for nice views but let in heat from the sun (forcing them to keep the air-conditioning dialed up) or leaked heat out (demanding mechanical heat to be pumped in). All the while, the lights were kept on around the clock, regardless of natural light levels.

A look inside the building where architects worked to ensure each designed decision had a real impact on sustainability.

To counteract this effect, Nordic shaped the expansion in response to careful sun studies. “The whole shape is generated by this energy-saving perspective,” said Stokke, explaining how the terminal's sloped wooden roof minimizes solar heat gain and loss. The materials—local timber and an environmentally friendly concrete made with local volcanic ash—further minimize the building’s energy footprint. “We were very conscious of the environmental lifecycle of the materials we used,” Stokke said.

In the summer, the building will be heated by something Norway has in abundant supply: snow. The design includes a system of reservoirs in which winter snowfall is harvested and covered with an insulating sawdust. As the weather warms, the snow is used to cool the building. “It will last until August,” Stokke claims.

Nordic’s design wasn’t just about technology and metrics, though. The firm was also concerned about the experiential dimensions of sustainability. By using vegetated green walls, water features, and by planting pine trees throughout the interior, Nordic created what Stokke calls “a green atmosphere, an easygoing approach to space,” achieving what can often be overlooked in green design: as he puts it, the “social aspects of sustainability.”

“Historically, airports and the entire air-traffic concept were not so concerned with the environment,” bemoans Stokke. With Nordic’s new expansion to the Oslo airport, though, that history is set to be revised.