BioCycle February 2006, Vol. 47, No. 2, p. 4
ECOROOFS ABOVE AND BIOENERGY AT THE PUMP
WE HEARD THIS WEEK from Terry Miller who is the Green Building Program Manager at the City of Portland, Oregon’s Office of Sustainable Development. We had asked Terry to provide his insights about the benefits of an ecoroof – the lightweight, low-maintenance vegetated roof system that the city is encouraging to promote sustainable development. It’s all part of the region’s strategy to do what’s necessary to achieve a better, more livable, healthier and stronger nation.
The advantages noted by Miller on Ecoroof benefits which are not found in conventional roofing are: Reduces rate and volume of storm water runoff, protecting nearby waterbodies, Lowers temperature of runoff, maintaining the cold stream temperatures needed by fish; Improves outdoor air quality by reducing smog; Increases vegetation and wildlife habitat on urban sites; Provides insulation for buildings; Lasts twice as long as a conventional roof; Creates a market for recycled materials such as compost and mulch; Creates jobs in related industries; and Can earn floor area bonuses for buildings in Portland’s Central City Plan District.
Portland currently has over two acres of planted ecoroofs with another two acres in planning or construction. Here are two examples:
Broadway Housing Complex – Portland State University hosts the city’s biggest ecoroof project. Planted with 11 species of sedum, sempervivum and wildflowers, the 15,239 sq ft area cost $21/sq ft and plantings will be irrigated for the first two years. This ecoroof will be monitored to measure its ability to reduce heat flux through the roof into the building.
Now in its seventh year, the Hamilton West Apartment building features one of Portland’s most well established ecoroofs – comprising about 70 percent of the roof area with soil depths ranging from three to five inches. The roof cost $10.50/sq. ft; plant materials consist of a mix of sedum, delosperma, wildflowers and grasses. Three years of monitoring demonstrate a 60 percent reduction in annual storm water runoff, which Miller calls “good news for nearby waterbodies.”
Ecoroofs and green roofs will be prominently discussed at the 22nd Annual BioCycle West Coast Conference to be held next month (March 20-22) at the Portland Marriott Downtown Hotel. The sessions on storm water management will analyze the impact of compost use, urban retrofits to clean up flows and protect property, and effective steps to improve soil permeability. Data on average pollutant loads and phosphorus concentrations using composted-amended vegetated strips will be compared to control sites with no compost. Staff at the city’s Bureau of Environmental Services will discuss best practices that include disconnecting garbage disposals and diverting dewatered high strength loads to food composting programs – also methods to integrate green building designs into reducing overflows. As will be explained by Leslie Hoffman of Earth Pledge, green roofs have a key role in managing urban water. (See her report in this issue on page 38.)
And with all the growing emphasis on how we as a nation can reduce imports of petroleum, there will be numerous topics dealing with renewable power alternatives – from the opening remarks about biomass resources and feedstocks by directors of Energy Trust and the Oregon Energy Department to the bioenergy potential in western forests. Step by step, we’re building our energy independence simultaneously as we increase organics recovery. These are the gutsy issues as we confront the future of waste management and build inspiration to accomplish much more. – J.G.