Key Takeaways
- A building’s carbon footprint has two parts, operational and embodied, and embodied carbon is locked in the moment construction materials are chosen.
- Up to eighty percent of a building’s embodied carbon comes from its superstructure alone.
- Mass timber cuts embodied carbon by up to seventy percent compared to conventional materials, a reduction that’s locked in for good once construction is complete.
A building's carbon footprint comes from two sources, operational and embodied. Operational carbon emissions are the energy consumed in a building over its lifetime through utility connections such as electricity and natural gas. For years, operational carbon has received most of the attention, in part because it's easier to measure. After all, energy consumption is reported each month in the form of utility bills.
That attention, however, has proven very beneficial. Advances in technology, from LED lighting and ENERGY STAR-rated appliances to high-efficiency heat pumps and smart thermostats, have measurably lowered how much energy commercial buildings need to consume in their day-to-day operations.
What Is Embodied Carbon?
Embodied carbon differs from operational carbon in that it's established before any of the tenants move in or pay any utility bills. Embodied carbon refers to the carbon that was released in the extraction, manufacture, transport, and assembly of all the various components that went into construction of the building.
Where the Opportunity Lies
Architecture 2030, a research and advocacy organization that is focused specifically on decarbonizing the built environment, estimates that the sector generates forty-two percent of annual global carbon dioxide emissions. Of that, twenty-seven percent comes from operational carbon, and the remaining fifteen percent comes from embodied carbon.
Clearly, there remains ample opportunity for improvement. The logical next step in making further reductions in greenhouse gas emissions is to put more focus on embodied carbon. A shift to more sustainable building materials, such as mass timber, does just that.
Why the Superstructure Matters
As much as eighty percent of a multi-story building's embodied carbon comes from its superstructure, or the columns, beams, and panels that hold it up. That concentration is exactly why the choice of construction materials is so consequential. Once a real estate developer makes that decision, a building's embodied carbon is locked in.
Locked In From Day One
Even a deep energy retrofit, the kind that meaningfully cuts a building's ongoing operational carbon emissions, typically takes around seven years to offset the embodied carbon spent making the retrofit itself. A new building carries no such recovery period for its superstructure. Whatever carbon goes into raising the frame is simply there, for the life of the building.
That's why it's so important to choose construction materials that minimize it from the outset. A mass timber building uses thirty-three percent less material by mass, and produces seventy percent less embodied carbon across its full life cycle.
