Two new reports on the topic of carbon emissions from building materials help set the stage for a deep debate in the industry on how to overcome the problems new construction faces as environmental impact and climate change regulations start to be discussed.
Thornton Tomasetti, an international engineering firm, has released results from its multi-year, project-based embodied carbon measurement study, identifying the type of structures, materials, and components with the highest carbon emissions. The findings provide insight into how structural engineers can drive innovation in design while reducing embodied carbon and creating structures that are more efficient.
Thornton Tomasetti’s embodied carbon measurement tool, Beacon, is expected be released to the industry and public for free by the end of 2019. The new tool is customized for structural engineers for embodied carbon optimization, allowing users to measure how they are doing while they are in the midst of working on a project.
Architecture 2030, a non-profit, non-partisan organization established in 2002 in response to the climate change crisis, claims half of global greenhouse gas emissions are associated with the building sector, including the industrial processes needed to produce materials for building construction. For more than a decade, the industry has targeted emissions reduction efforts on operating energy—areas where mechanical engineers and architects specify materials, designs, and equipment to increase efficiency. A new focus on reducing the carbon footprint of building materials enables structural engineers to make a substantial contribution to mitigating climate change since the most commonly used structural materials—concrete, steel, and aluminum—contribute more than 22% to global carbon dioxide emissions. In a typical building, 55% of embodied carbon is in the structure and substructure.
The largest driver of embodied carbon reduction in structures in the last seven years has been a market-driven trend toward the increased use of recycled steel and supplementary cementitious materials such as fly ash. While LEED (Leadership in Energy and Environmental Design) certified buildings show slightly lower embodied carbon levels than non-LEED buildings, concrete structures show less embodied carbon levels than steel buildings and all building types—with the exception of aviation, sports, and mission critical facilities—have the highest proportion of embodied carbon in their slabs.
Alternative, low carbon slabs such as hollow core, voided slabs, or timber floors may be considered to reduce embodied carbon. In aviation and mission-critical structures, the foundations hold the greatest embodied carbon, while in sports structures, the most embodied carbon is in the structural framing.
Unfortunately, mission-critical structures such as hospitals and data centers have the overall highest levels of embodied carbon of any asset category. Skyscrapers show the highest proportion of embodied carbon in their columns rather than foundations.
The second report, from the Urban Land Institute’s Greenprint Center for Building Performance, Embodied Carbon in Buildings Materials for Real Estate explains how reducing embodied carbon in the construction process can save developers money and help mitigate the impacts of climate change. Greenprint is a worldwide alliance of leading real estate owners, investors, and strategic partners committed to improving the environmental performance of the global real estate industry. Through measurement, benchmarking, knowledge sharing, and implementation of best practices, Greenprint and its members are striving to reduce greenhouse gas emissions by 50% by 2030.
In some cases, due in large part to carbon-intensive material manufacturing processes and the large quantities of fossil fuels used before materials ever reach the construction site, embodied carbon can account for as much as half of a building’s total carbon footprint over its lifetime. To achieve ambitious climate goals, such as those set in the Paris Climate Agreement, addressing embodied carbon will need to be part of real estate’s climate mitigation strategy.
The report details multiple steps that constructors and developers can take to reduce their embodied carbon, many similar to those projected by Thornton Tomasetti. Builders should consider low-carbon structural materials, such as green concrete, recycled steel, or mass timber; reduce the total materials in building design, which can result in lower costs as well; repurpose used materials as much as possible, which can add authenticity to a project; specify lower-carbon materials when offering an RFP (request for proposal), which often comes at no added cost; calculate the embodied carbon of the materials in the project, to understand the emissions impacts and prepare the building for eventual embodied carbon reporting regulations, which may be enacted by local municipalities; and promote the embodied carbon reductions gain community goodwill and grow market awareness and adoption of reduced embodied carbon buildings.
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