Modeling Lifetime Carbon: Operations + Embodied + Transportation – Greenbuild 2020 Session Review

Suboptimization of carbon reduction strategies is unavoidable when significant portions of a project’s greenhouse gas (GHG) emissions are ignored.

Traditionally building energy performance in energy codes and rating systems have used energy cost metrics. Net zero definitions typically use annual energy consumption as a metric. Some codes and standards are moving toward energy use intensity. Occasionally building energy use is converted into GHGs with annual emissions factors. With electrical grids decarbonizing and regionally varying based on seasonally available renewables, hourly grid emissions data are better predictors of energy consumption-related GHGs.

Meanwhile as net zero codes reduce building energy use, the carbon emissions related to the construction materials increase as a percentage of the project’s overall GHGs. This has raised awareness of embodied energy and carbon. Nevertheless, too few are utilizing these tools to reduce their carbon footprints which largely occur during construction.

Transportation emissions can easily eclipse both operational and embodied carbon, yet project’s transportation-related emissions are rarely attributed to the property, which undermines the importance of location efficiency. Transportation alternatives vary across every metropolitan region. Electric vehicle uptake will also vary geographically. LEED Zero Carbon is a rare exception with the inclusion of transportation-related emissions, but the rating system is only applicable to existing buildings, when the projects are out of the designers’ control.

Designers need tools to assess all their projects’ lifetime GHG emissions prior to construction to make informed decisions regarding choices which have larger impacts on reducing carbon emissions related to the built environment. Excluding any of these components in a net zero definition, risks suboptimization at the expense of the possibility of a more climate-responsive design. Our panel will review methodologies with examples to assess all these elements over a 30-50-year timescale during the design phases of a project to Design for LEED Zero Carbon.

LEARNING OBJECTIVES:

Grasp how electrical grid decarbonization will vary emissions over time–hourly to annually and from region to region–while learning the distinction between average emissions and marginal emissions.

Learn how to apply hourly electrical grid emissions profiles to energy models’ hourly results to create annual and lifetime building energy use carbon emissions (included in LEED Zero Carbon).

Discover tools and methods to assess the location efficiency and transportation energy intensity of a given project site for a proposed project type (included in LEED Zero Carbon).

Understand life cycle assessment (LCA) methodology and available Whole Building LCA tools to identify strategies to reduce embodied carbon on projects (not currently included in LEED Zero Carbon).

CE HOUR(S): 1.5

GBCI, AIA LU HSW

Ankur Podder
Research Engineer
National Renewable Energy Laboratory
Ankur joined the Commercial Buildings Research Group at NREL in 2019 as a Research Engineer, with a focus on buildings advanced manufacturing and integration science. His work includes facilitating integration of a wide range of energy-efficient strategies and distributed energy resources during factory production of permanent modular buildings, strategizing the blending of factory information modeling and building information modeling into NREL’s building energy modeling capabilities, and accelerating whole-buildings systems integration in upcoming net-zero energy buildings. Ankur gained academic and research training on advanced manufacturing, life-cycle assessments, and buildings energy from Massachusetts Institute of Technology (MIT); entrepreneurship and economics from courses at Harvard Business School; and architectural and building sciences/technology from Birla Institute of Technology. At MIT, he developed digital design-manufacturing methods to quantify and lower material-embodied energy during new construction.