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Chief engineers from Portland鈥檚 infrastructure bureaus聽鈥� Environmental Services, Water, and Transportation 鈥� have approved recommendations to add concrete embodied carbon threshold requirements for all city construction projects. This is in line with the city鈥檚 commitment to climate action and leadership.

鈥淢ost of us don鈥檛 think much about the concrete beneath our feet,鈥� stated Stacey Foreman, manager of the city鈥檚 Sustainable Procurement Program, in a news release. 鈥淎s the most widely used building material in the world, it has a significant environmental impact. Portland is a leader in establishing these thresholds and in our approach of bringing multiple stakeholders together to develop them.鈥�

The largest component of concrete is cement. Its production alone generates 8 percent of global greenhouse gas emissions.聽The lower-carbon mixes can be designed to perform as well as conventional concrete (or even better), and are competitive in cost.

When considering all city projects that use concrete, the annual reduction is significant. The聽city uses concrete for a high volume of projects, including sidewalks and ADA ramps, bicycle and pedestrian paths, fire hydrant pads, retaining walls for parks, and large infrastructure projects such as the Water Bureau鈥檚 Bull Run filtration facility and the Bureau of Environmental Services鈥� wastewater and stormwater infrastructure. By adopting higher sustainability standards for concrete, bureaus will accelerate their use of concrete that is durable and that has been manufactured with lower climate impacts.

The new standards will take effect in January 2023, but some projects under way have low-carbon concrete. Some include BES鈥� Northwest Thurman Street Reconstruction Project and Downtown-Old Town Sewer Repair Program, PBOT curb ramps, the Water Bureau鈥檚 Washington Park Reservoir project and Portland Parks & Recreation鈥檚 Gabriel Park playground.

The new requirements will accelerate the city鈥檚 use of low-carbon concrete, and create a framework for a consistent, trackable and enforceable low-carbon standard.聽The city developed the new requirements with a multidisciplinary stakeholder group that offered recommendations on reducing the carbon footprint of concrete used on city projects. Implementation of the requirements will result in a reduction of greenhouse gas emissions by 3 percent to 35 percent over historically used concrete mixes. For example, for a large project like a new water reservoir, a 19 percent reduction in concrete-embodied carbon is the approximate equivalent of removing 754 gasoline-powered cars from roads for one year.

鈥淭his has been a unique and thoughtful process that has taken stakeholder recommendations into account through the implementation at every stage,鈥� Michael Bernert, vice president of Wilsonville Concrete Products, a stakeholder committee member, stated in the news release. 鈥淭his process involved engineers, contractors and suppliers, which is not always the case.鈥�