When comparing a high-performance building to a code-minimum building, a surprising truth emerges: their embodied carbon footprints are almost the same. If we were to think about how materials are extracted, manufactured, transported, and assembled, the carbon emissions related to those processes remain a common thread in buildings regardless of energy performance.
Our industry generates almost 40% of all carbon emissions globally, defined in two broad categories: operational carbon from building operations, and embodied carbon from materials and construction. Operational emissions can be reduced and offset through passive thermal design, high-efficiency HVAC, on-site renewable energy, heat pump water heaters, and other operating system measures. Reducing these emissions is imperative for long-term carbon reduction over the life of a building.
Embodied carbon, on the other hand, is the building’s carbon footprint before it even opens its doors. It cannot be offset via operational systems, thus making how our buildings are constructed and the materials used a vitally important consideration. Portland cement and steel are typically high in embodied carbon, for example, while local, sustainably forested wood is low.
Climate science informs us that reducing carbon emissions in the short-term (next 10 years) is critical, so decisions regarding embodied carbon are magnified since most of a building’s carbon in the short-term is embodied carbon. This graph shows how high-performance buildings typically reduce emissions by 25%, leaving the overall carbon emissions for the life of the building almost 3/4 embodied carbon and 1/4 operational carbon.
Source: https://www.payette.com/research-innovation/its-time-to-talk-about-carbon-part-2/
Understanding a product’s embodied carbon and environmental impacts is crucial for overall carbon reduction goals. Websites and databases such as the Carbon Smart Materials Palette, the EC3 tool, the ICE database, the Athena Impact Estimator, and Tally all provide embodied carbon information for materials and buildings. These sites can help increase awareness and track carbon emissions both of a material’s production and its transportation.
Understanding more about what we use in our buildings today can help us build a less carbon-intensive building of tomorrow. Looked at another way - reducing our embodied carbon footprint ensures that our planet is healthy long enough for the reduction in operational carbon to matter.