Carbon Choices – Bringing C02 into Life-Cycle decision-making 

Donald Davies
President, Magnusson Klemencic Associates, Seattle, Washington USA

The environmental impacts of our infrastructure choices are regularly considered, but only recently has the evaluation of the embodied carbon of our building materials and construction processes been credibly possible. Practical and timely embodied and operational carbon accounting is still an evolving science, with confusion in the industry for when and how to best use this information.  Life Cycle thinking is the key to organizing how this information gets used, and to bring clarity to its value in decision making processes. This paper considers the state of environmental Life Cycle Analysis (LCA) within the United States from a structural engineer’s perspective. It includes updates on recent information releases by the US Concrete, Steel, Masonry, and Timber industries; efforts by organizations to collect, disseminate, or otherwise manage this data; and the results of three case studies of how this information can be used for informed decision making. With the need for credible information that can facilitate a project’s decision making process, the paper also proposes an organization for when, and to what level of detail, environmental LCA data should be considered for triple bottom line decision making.  In keeping with the principles behind a US LCA Practice Guide for Low Carbon Construction currently under development, a multi stepped process is suggested with LCA evaluations within the design, procurement, and as-built milestones of a project’s delivery.