Green roofs have a net benefit for public and private property where they are employed as part of the city of Portland’s urban stormwater strategy.
(2008) David Evans and Associates, Inc. and ECONorthwest for the City of Portland. Ecoroofs are expected to be an important part of Portland’s urban strategy as the city grows and density increases. Although green roof technology is not new, quantifying their costs and benefits will help us understand the role they have in the Pacific Northwest. Over 40 years the net benefit to the private property of an ecoroof is $404,000. Ecoroofs provide immediate and long-term benefits to the public: At five years, the benefit is $101,660, and at 40 years the benefit is $191,421. Benefits are generated from reduced stormwater management system improvements and operating and management costs, carbon reduction, improved air quality and habitat creation.