The carbon footprint of the built environment is simply massive—in the extraction, fabrication, transportation and erection of construction materials, but also in how we operate and maintain a structure after it’s built. Reduction of the latter, or operational carbon, is better understood and has been promoted through leadership tools like LEED® followed by regulatory legislation across the country.
Seventeen states, which make up 47 percent of the U.S. economy, have signed the U.S. Climate Alliance Agreement with the aim to reduce emissions by 26-28 percent by 2025. Two hundred and seventy-four cities have signed the Mayors National Climate Action Agenda and eight states follow the Paris Agreement. New York City made news earlier this year when it passed a resolution requiring extraordinary energy performance gains to the city’s largest commercial buildings by 2030.
It’s clear that municipal and state governments are aiming for long-term, affordable decisions that reduce carbon emissions. However, while operational carbon is important, we are only addressing part of the carbon reduction challenge.
The urgency of embodied carbon
According to Architecture 2030, between 2015 and 2050, 2 trillion square feet of buildings will be built or undergo a significant renovation. Over the 30-year lifecycle of a new building built in 2020, roughly half of its carbon would come from embodied carbon and the other half from operational carbon. Carbon from building operations will be emitted bit by bit every year over the life of a building, but all embodied carbon will have been emitted the day construction is complete and we hand over the keys. To be clear, we need to address both operational and embodied carbon. With that said, addressing embodied carbon is more urgent.
The United Nations’ Intergovernmental Panel on Climate Change (IPCC) 2018 report states that for global warming to be limited to 1.5 °C, "Global net human-caused emissions of carbon dioxide (CO2) would need to fall by about 45 percent from 2010 levels by 2030, reaching 'net zero' around 2050." This means that there is a greater urgency to address embodied carbon because, over the next ten years, about 80 to 90 percent of the carbon emitted from new construction will be embodied carbon.