UC Berkeley

While recognized as important, calculation of embodied energy and greenhouse gas (GHG) emissions associated with buildings, especially at a large scale, has scant literature. A model has been created for estimating the inventory of structural and non-structural materials and building components and their associated embodied energy and GHG emissions for the approximately 807,400 office buildings constructed in the United States between 1946 and 2018. The buildings were modeled using eight prototypical designs. We estimate that 1100–1300 million metric tons of materials are embodied in these 807,000 buildings (90% of which have just 1–3 floors), as well as 6–7 years' worth of national construction and demolition waste. In total, 6.5 billion Gigajoules of primary energy use (∼6% of the U.S.’s 2021 energy consumption) and 0.5 billion metric tons of carbon dioxide equivalent emissions (∼8% of the U.S.’s 2020 total GHG emissions) are estimated to be embodied in these buildings. One-floor steel and wood buildings were about equally GHG intensive from structural materials as well as combined structural and non-structural materials perspectives, while reinforced concrete (RC) buildings were 50% and 27%–47% more GHG intensive, respectively. From the all-materials-use perspective, 5-floor steel buildings were 54% more GHG intensive to construct than wood buildings, and in turn RC buildings were 68% more GHG intensive than steel buildings. Non-structural material contributions were significant. Increasing economies of scale in embodied impacts can be observed as the number of floors increases. Results constitute points of reference for those who seek to find ways of reducing the carbon footprint of buildings.