Sustainable / Green

Sustainable or green architecture is defined by performance targets, mainly low energy use and low carbon emissions, rather than by one set of forms. The features most often visible outside are planted roofs and walls, external fins or louvers that shade windows from direct sun, rooftop solar panels, and exposed structural timber in place of concrete and steel. Less visible features include thick insulation, airtight construction, rainwater collection and windows placed for natural ventilation and daylight.

Stefano Boeri's Bosco Verticale in Milan (2014) is a pair of residential towers planted with about 730 trees and thousands of shrubs on their balconies. Renzo Piano's California Academy of Sciences in San Francisco (2008) has a 2.5-acre roof planted with 1.7 million native plants and edged with solar cells. The Bullitt Center in Seattle (2013), designed by Miller Hull, has a heavy timber frame, 575 rooftop solar panels, composting toilets and a 52,000-gallon rainwater cistern.

The 1987 report Our Common Future, from the United Nations' World Commission on Environment and Development, defined sustainable development as development that meets present needs without compromising the ability of future generations to meet their own. In 1990 Britain's Building Research Establishment launched BREEAM, the longest-established building sustainability rating. In Darmstadt, Germany, four terraced houses built in 1990-1991 with Wolfgang Feist became the first built to what became the Passive House standard, which cuts heating needs through insulation and airtight construction.

The U.S. Green Building Council, founded in 1993, piloted its LEED rating system in 1998. Norman Foster's Commerzbank Tower in Frankfurt (1997), with sky gardens that bring daylight into its offices, has been called the first ecological skyscraper. The Bullitt Center was certified as a Living Building, one of the strictest green standards, in 2015. Mass timber, in which glued and cross-laminated wood panels carry the structure, reached 18 stories with Mjøstårnet in Brumunddal, Norway (2019), and Ascent in Milwaukee overtook it as the tallest timber building in 2022.