What is an eco-roof or a green roof? Eco-roofs or green roofs are roofs that are covered with living plant material.  Much of our land area consists of impervious surface (think tar roofs and paved streets) and eco-roofs minimize the footprint of a roof by absorbing some of the rain that would otherwise become stormwater runoff which pollutes our rivers. The Portland metropolitan region has one of the highest numbers of eco-roofs in the country. Since 1996, more than 120 eco-roof projects have been constructed in Multnomah County, totaling approximately 10 acres. Take a self-guided tour of some of these roofs. Eco-roof tour guide.

Amy Joslin Eco-Roof on the County Headquarters Building

Amy Joslin Eco-Roof on the County Headquarters Building

The Amy Joslin Memorial Eco-Roof is open to the public during business hours at the Multnomah Building, 501 SE Hawthorne, Portland, Oregon. Take the elevator to the fifth floor to see this 11,893-square foot eco-roof retrofit that evaporates about 25% of  the buildings rainwater runoff and reduces the air conditioning load between 5-10%. The eco-roof includes and informative interpretive display. Take the #6, #14, or #10 bus or simply walk across Hawthorne Bridge from downtown.

The Amy Joslin Memorial Eco-Roof was dedicated on November 10, 2005 in honor of Ms. Joslin's commitment to sustainability and her leadership in the development of the eco-roof at the Multnomah County headquarters building.

Central Library Eco-Roof

Central Library Eco-Roof

The Central Library Eco Roof is expected to be constructed and open for scheduled public tours in the summer of 2008.  The eco- roof on this landmark building in downtown Portland will provide an unprecedented opportunity for public education on sustainability issues such as stormwater runoff, energy efficiency, and the heat island effect.  In addition, the eco-roof is expected to save the county money in energy costs and maintenance costs.

The Oregon Department of Environment Quality and the City of Portland awarded grants to Multnomah County to construct the eco-roof on the county's historic central library building.  The DEQ grant, $102,000, and the City of Portland grant, $60,000, will be used to offset the approximately $180,000 construction and maintenance costs. 

Wildflowers on Multnomah Headquarters Eco-roof

Benefits of Green Roofs

  • The aesthetics of being surrounded by garden-like settings
  • Better energy efficiency and minimization of the "heat island" effect that leads to increased temperatures in urban areas
  • Mitigation of storm water runoff which causes flooding, increased erosion, and which may result in raw sewage that is discharged directly into our rivers.  Eco-roofs can absorb stormwater and release it slowly over a period of several hours.  Green roof systems have been shown to retain 60-100% of the stormwater they receive
  • In addition, while eco-roofs do cost more than a conventional roof, they also last longer and their added insulation leads to energy savings which offsets the added expense