Comparing LCA Results with Biogenic Carbon

One study from New Zealand (Fernandez 2008) demonstrates the varying carbon emission results by comparing LCAs of the same building designed using four different primary building materials and two different LCI data sources.  Embodied carbon emissions factors in Figure 2 sourced from the a New Zealand dataset (Alcorn 2003) included biogenic carbon (negative indicating carbon sequestration) while the factors in Figure 3 from the GaBi inventory did not. 

Figure 1, Embodied CO2 for Four Buildings, Alcorn Database

Because the treatment of biogenic carbon in an LCA can result in significantly different conclusions, the World Resource Institute/World Business Council for Sustainable Development Greenhouse Gas Protocol (World Resources Institute 2011) recommends that biogenic carbon absorption and emissions be reported as a separate inventory item.  LCAs that report biogenic carbon in this manner are most transparent.  The LCI data for U.S. wood processes and products reported in the National Renewable Energy Laboratory’s LCI database and in CORRIM Reports does not include biogenic carbon, however, the carbon sequestered in a piece of lumber can be estimated based on wood chemistry.   

Figure 2, Embodied CO2 for Four Building Types, GaBi Database