UW Today

April 23, 2013

A greener concrete? UW-led coalition seeks to reduce concrete’s carbon footprint

News and Information

Concrete is the most widely used manmade material in the world. Each year, more than 1 cubic yard of concrete is created for every person on the planet.

Every year the United States alone uses about 300 million cubic yards of ready-mix concrete to make streets, bridges, buildings, dams and driveways — and it lasts a very long time.

But, what if concrete could be made “greener”? What would the global energy savings be if concrete had a 50 percent smaller carbon footprint?

Concrete is typically made of a combination of cement, rock, sand and water. To produce cement, materials are heated in a large kiln that emits greenhouse gases through the burning of fossil fuels and a chemical reaction termed calcination.  Rock and sand also must be processed and transported, and all these processes have environmental impacts.

That’s the question being addressed by the University of Washington-led Carbon Leadership Forum, an alliance of researchers, associations and companies in the building industry formed to develop what are called environmental footprint standards for building materials, especially concrete.

Those standards, also called product category rules, are designed to meet goals expressed by Architecture 2030, an industry nonprofit working to dramatically reduce energy consumption and greenhouse gas emissions in the manufacture and transport of construction materials. More specifically, Architecture 2030 came from the group’s 2030 Challenge for Products, which seeks a 50 percent reduction in carbon-equivalent product footprint by 2030.

The standards alone don’t create energy savings, of course — they’re designed to enable direct comparisons of building materials from different manufacturers.

Methods already exist for reducing concrete’s environmental impact, such as replacing cement with ash from coal-fired power plants, called fly-ash. Innovative manufacturing methods and materials also are being developed.

But before now, there was no method to consistently compare different concretes to ensure selection of a lower environmental impact concrete.

“We already know how to specify concrete for a lot of performance characteristics — strength, shrinkage, permeability,” said Kate Simonen, UW assistant professor of architecture and director of the forum. “Now, people who want to specify environmental performance as a different performance characteristic will have a method to compare it.”

Simonen said that the results of these standards, called Environmental Product Declarations, help users understand and compare the environmental impacts related to product manufacturing, use and disposal, roughly the same way a nutrition label shows the ingredients in a food product.

She said the standards also will provide “quantifiable life-cycle information” to enable comparisons among products fulfilling the same function. Life-cycle assessment measures a project’s total environmental impact from design and construction through its entire use and end of life.

The standards will have practical applications, such as helping a city or company set and meet specific targets for reducing carbon use. Cities trying to push their carbon use even lower will be able to specify low-carbon concrete. Users who might be willing to pay a higher price for a lower-environmental-impact concrete could provide financial incentive to advance developing technologies.

Ed Mazria, Architecture 2030 founder and CEO, praised the standards. “Reducing the carbon footprint from concrete is one of the most significant actions that the building sector can take. The Carbon Leadership Forum recognized this issue, and its members set in motion a process for developing clear rules to govern the environmental reporting for concrete mix designs.”

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For more information or interviews, contact Simonen at 415-641-1421 or ksimonen@uw.edu. A copy of the new product category rules and environmental product declarations is available on request.

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