It is estimated that carbon emissions will reach the “tipping point of runaway climate change,” increasing the Earth’s temperature by 1.5 degrees Celsius, in 2040. Engineers globally are working to combat climate change through innovations in renewable energy sources, energy efficiency and carbon sequestration. Among those working to address such a daunting and urgent threat is a team of interdisciplinary, University of Michigan researchers led by CEE Professor Victor Li under the newly-founded Center for Low Carbon Built Environment (CLCBE).
The CLCBE seeks to reduce carbon emissions stemming from the built environment by 50% by 2030. The effects of such a reduction would be monumental for climate change response, as more than half of carbon emissions are produced by the maintenance and upkeep of structures such as buildings, bridges and roads.
“Many recognize that the built environment is a problem in its outsized carbon and energy footprints. I would like to think of the built environment as a gold mine in addressing climate change in a big way, just because there are so many opportunities to reduce emissions and even to utilize CO2 as a valuable resource,” said Li.
Much of the center’s focus is on concrete, as it is the second most consumed material in the world and the highest-volume manufactured product. It also emits enormous amounts of carbon, yielding seven percent of global carbon emissions. One solution put forth by the CLCBE is Engineered Cementitious Concrete (ECC), also known as bendable concrete. ECC is an advanced fiber-reinforced concrete that is far more flexible than traditional concrete, which is quite brittle by comparison and cannot stand extreme loads. Whereas regular concrete crumbles under pressure, ECC develops much smaller tears, which then “self-heal” when exposed to water and air. This means that ECC lasts far longer than traditional concrete, thus reducing the amount of new concrete — and in turn the resulting carbon emissions — required to construct and maintain buildings and bridges.
Bendable concrete is already cutting emissions globally and locally; the material is in use on six continents. Notably, ECC is in several bridges and buildings across Japan and on the Grove Street Bridge in Ypsilanti, where it is estimated to have reduced emissions by 39 percent.
The center describes their production process as a “life-cycle approach to carbon reduction in building,” meaning that, as opposed to more linear, segmented approaches to design and construction, the CLCBE seeks to integrate sustainability into all steps of the building cycle.
“Reducing carbon in cement and concrete is necessary, but it is critically important to recognize that design and construction have strong influences on operational carbon. Life-cycle thinking is necessary to truly and rapidly decarbonize the built environment,” said Li.
For buildings, this means addressing the huge amounts of energy and carbon associated with heating, cooling, and dehumidification. Similarly for transportation infrastructure, the energy and carbon associated with repeated repairs are simply not sustainable. End of life is also important. Li imagines a future where one day we will be able to design and build with zero waste going into landfills.
A prime example of this type of approach can be seen in RecoBlox™: modular, reconfigurable construction blocks fitted with sensors. The 3D-printed blocks, made of ECC and utilizing advances in robotics, are meant to be completely reused. Not only do RecoBlox offset carbon in construction, but their use of robotics minimizes safety risks in construction and directly addresses the productivity gap in the construction industry.
Such a strong emphasis on reuse and integrated design require interdisciplinary cooperation. The CLCBE partners with several departments within U-M, including the Taubman College of Urban Design and Planning, the Global CO2 Initiative, Mcity and Tech Transfer, as well as with external organizations, including HOK Design and the University of Cambridge.
“The major challenge to cutting emissions in the built environment is the wide range of stakeholders whose goals are not always aligned,” Li explained. “There are gaps between various entities that make up the value chain of construction – investors, developers, owners, users, material suppliers and the architecture, engineering and construction (AEC) industry. The CLCBE serves as a platform that helps to bring these diverse groups together to rapidly and collaboratively drive down carbon emissions in the built environment.”
This article is included in the Fall 2020 issue of the CEE Review magazine. Visit the issue home page to see other articles.