Designing to reduce a building’s embodied carbon

by Stephanie Fargas

The carbon footprint of the design and construction industry reaches far beyond the boundaries of a single building or site. Due to various processes, ranging from the extraction of raw materials to manufacturing and installation of the construction materials, the impact of a single project includes both embodied carbon within the built environment and operational carbon generated throughout the life cycle of the structure. Embodied carbon is defined as the carbon dioxide (CO₂) emitted during the full life cycle of a product from extraction (cradle) to the use and disposal phases (grave).

Construction products contribute to 11 per cent of global greenhouse gas (GHG) emissions (For more information, read the 2017 and 2018 United Nations (UN) Environmental Global Status reports.). Canada’s GHG emissions from the built environment is 17 per cent (residential, commercial, and institutional buildings) (Consult the 2016 Pan-Canadian Framework on Clean Growth and Climate Change.). There has been significant strides in reducing operational carbon by improving the energy efficiency of mechanical and electrical systems, and integrating renewable energy resources. However, designing to reduce embodied carbon has not been an area of emphasis in the design community, or a mandatory policy in Canada.

With recent efforts from Architecture 2030 (the American Institute of Architects [AIA] 2030 and 2050) and sustainability certification programs, such as the Leadership in Energy and Environmental Design (LEED), Envision, and the Living Building Challenge (LBC), awareness has been raised on the importance of designing for low embodied carbon to address climate change.

This lack of emphasis has not prevented the design and construction industries from taking heed of the urgency of the current climate crisis or from utilizing available tools to plan and execute buildings that are both beautiful and low-carbon or carbon-neutral. In fact, the opportunities for these industries to become leaders in carbon solutions are just beginning to be tapped. This article focuses on how the industry can design for low embodied carbon solutions in new and existing buildings.

Architecture 2030 was established by AIA in 2006 to address climate change through sustainability-driven solutions and carbon-neutral design in the built environment. It established targets toward zero emissions including a 70 per cent reduction in GHG related to energy consumption below a comparable building type for new and existing structures in specific geographical locations. Since its establishment, more than 1200 design, architecture, and engineering firms have signed on to monitor their progress toward the agreed-upon goal. Additional metrics were established for subsequent years—for example, by 2020 an 80 per cent reduction, 90 per cent in 2025, and carbon-neutral in 2030 (i.e. complete elimination of fossil fuel sources from building operations). Further, AIA, the Royal Architectural Institute of Canada (RAIC), Ontario Association of Architects (OAA), U.S. Green Building Council (USGBC), Canada Green Building Council (CaGBC), and several countries, states/provinces, and cities have also advocated and adopted these policies. The CaGBC has developed the Zero Carbon Building Standard to address and achieve the climate change commitments Canada has signed onto and provide guidelines for zero-carbon design for new and existing buildings of various project typologies (e.g. institutional, commercial/office, residential, and commercial warehouses). Through this standard, projects are to demonstrate a net emissions balance of zero or less for building operations. Emissions generating GHG are offset by renewable energy sources on or offsite. Two projects have been certified as zero-carbon buildings—evolv1 in Waterloo, Ont., and Mohawk College’s Joyce Centre for Partnership and Innovation in Hamilton, and 16 projects are enrolled in the program. Currently, the Zero Carbon Building Standard is not mandatory, but rather a guideline for consultants and owners to follow.