night view of Bio4 power plan illuminated facade

Speirs Major Brings an Illuminated Forest to a Biomass Power Plant

Clad in a thicket of tree trunks, the BIO4 facility is a symbol of Copenhagen’s renewable energy revolution.

A design firm specializing in “using light and darkness to enhance the visual environment” has activated the dynamic, forest-inspired facade of Copenhagen’s new wood-burning power plant.

Speirs Major’s lighting design for the BIO4 facility, which is located only a mile from the city’s downtown, is meant to draw the public’s attention to the Danish capital’s transition to renewable energy.

The building, designed by Gottlieb Paludan Architects, is clad in hanging tree trunks, creating a thicket that is 19 feet deep. A prominent staircase takes visitors from ground level up through the trees and to the roof, providing views into the plant’s interior along the way, and across to neighboring Sweden from the top.

“We wanted a very natural effect,” says Speirs Major senior partner Keith Bradshaw. “We really liked the idea that you are looking into a forest at night, and it is beautiful and enticing, but at the same time kind of unsettling. Often in stories about forests—be it ‘Hansel and Gretel,’ The Blair Witch Project, or even Bambi—you have that sense of being beckoned in. When you get close to this facade, you really do feel like the light of a forest is moving through. It is very, very suggestive.”

Designed to be a symbol for the city, the plant is illuminated by a warm white glow under normal circumstances, but transforms into a dramatic red on Danish Constitution Day and a striped rainbow during Pride celebrations. 

“The effect is really special,” says Bradshaw. “The building has this ability to say, ‘We’re part of this city and we’re part of this nation.’ ” 

view looking up the stairs inside bio4's illuminated facade.
By day, natural light creates a dappled shadow effect through the trees (above). After dark, layers of immersive illumination continually shift in speed, focus, and intensity to cast patterns that never appear the same way twice (top). The Speirs Major team relied on extensive testing and physical and virtual modeling to design the installation, but it was executed partly using traditional theatrical projection techniques.

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