The Works

Portland Walmart Does Green Roofs Better Than San Francisco

Credit: Walmart

A one-story, 90,000-square-foot Walmart with an enormous surface parking lot off of I-5 in Portland doesn’t sound like the greenest thing in the world. But the company is taking one small step toward environmental friendliness: It announced on Wednesday that it’s partnering with Portland State University on a green roof planned for a store in Hayden Meadows, just south of the Columbia River dividing Oregon from Washington.

The green roof will become a laboratory for future projects, replete with all of the green-tech buzzwords you’ve come to know and love (white membrane rooftop! stormwater runoff!), and more (bird count surveys!). Quoth the press blast:

PSU’s Green Building Research Laboratory will lead the effort to deploy scores of sensors and a weather station on Walmart’s new Hayden Meadows store in North Portland, which will feature 40,000 square feet of vegetative roof installed in three separate sections—each devoted to testing different aspects of green roof design, such as materials and soil depth. The remaining 52,000 square feet of white membrane rooftop will also be monitored by sensors, providing an opportunity to deliver side-by-side comparisons on factors including surface temperature, water flow and building operations. Data collected from the Hayden Meadows roof will be compared to similar data collected on a Walmart green roof in Chicago, providing a comprehensive view of green roof performance in various conditions.

“The data we collect will help the green building industry improve upon the many benefits provided by green roofs—from reducing heat island effects to improving overall building performance,” said David Sailor, director of the PSU Green Building Research Laboratory and professor of mechanical engineering. “This research project will lead to better green roof design for buildings around the world.”

The PSU Green Building Research Laboratory, housed at the Maseeh College of Engineering and Computer Science and funded in part by the Institute for Sustainable Solutions, will lead the two-year research project working with students and community partners. The city of Portland’s Bureau of Environmental Services will measure stormwater runoff; the Cadmus Group, an environmental consulting firm, will monitor the performance of the rooftop air conditioning units; and the Audubon Society of Portland will conduct bird count surveys to contribute to the habitat monitoring portion of the study.

Meanwhile, a few hundred miles south of Portland, one San Francisco urban advocacy group wants to make it easier to build green roofs in that city, which it says “lags substantially behind others such as Portland, New York, Chicago and Toronto in both green roof policy and on-the-roof implementation.”

SPUR issued a report on Monday that identifies ways to make the City by the Bay more green roof-friendly. These include financial incentives and a manual for how to implement the roofs. But perhaps the most important recommendation comes first: Reducing the regulatory barriers for those who want to install green roofs on their own dime.

“In some cases,” reads the report, “codes that were intended for a wide range of uses, such a plumbing and fire codes, are not clear in their application to living roofs. This lack of clarity can result in delays in the permit process, changes to designs and even hesitation by designers and contractors to proceed.”

Even in the case of exceptions in the code — SPUR notes that buildings are generally allowed a four-foot height exemption for landscaping — confusion persists among those who wish to build them, which SPUR wants the city to eliminate by issuing clearer rules. “This could result in a process diagram clearly explaining which types of roofs trigger which permits and inspections,” the report continued, “whether different permits apply to residential and commercial buildings, and under what thresholds the requirements may be different.”

The whole report is available here as a freely-downloadable PDF.

The Works is made possible with the support of the Surdna Foundation.

Stephen J. Smith is a reporter based in New York. He has written about transportation, infrastructure and real estate for a variety of publications including New York Yimby, where he is currently an editor, Next City, City Lab and the New York Observer.

Tags: infrastructurethe workssan franciscoportlandregulationswalmartspurgreen roofs