It is time for building design professionals to track and report the embodied carbon of their projects.
Embodied carbon refers to the carbon dioxide emitted during the manufacture, transport and construction of buildings materials, together with end-of-life emissions.
The imperative is clear.
Buildings are responsible for about 40 percent of global CO2 emissions — over a quarter of which is from the embodied carbon of materials and construction.
As Ed Mazria has recently noted, quickly reducing the embodied carbon in building materials and construction over the next decade is critical. For all of the buildings built between 2021 and 2030, embodied carbon will be responsible for 72 percent of their total CO₂ emissions.
We have the tools to predict it.
In pursuit of carbon-neutral buildings, design teams are encouraged to conduct whole building life-cycle analyses on projects.
There are a range of tools now available to help teams model and optimize the embodied carbon of their projects. The Athena EcoCalculator, Tally, EC3, OneClick LCA, and eTool all offer unique opportunities for project teams to assess embodied carbon. When using any of these tools, teams are encouraged to be mindful of LCA stage and scope to better ensure the accuracy of predicted results.
We have a platform to report it.
The Carbon Leadership Forum (CLF) at the University of Washington continues to stand out as one of several industry leaders conducting substantive research into the embodied carbon of buildings.
However, when it comes to platforms for tracking and reporting the predicted embodied carbon of projects, the American Institute of Architects (AIA) offers a platform that design firms may be interested in. The AIA recently redesigned their Design Data Exchange (DDx) for 2030 Commitment signatory firms. With the update comes several new features including the ability to report embodied carbon.
It will be messy, but it is necessary.
Indeed, design firms tracking and self-reporting predicted embodied carbon is not standardized or subject to quality assurance protocols. The process will be messy. However, if we’re being honest, let’s admit that predicting the operational energy and carbon consequences of our building projects has always been messy. But that has never stopped us from moving forward, learning from each other, and improving the way we work—nor should it stop us now.
Included here is a snapshot of a handful of projects for which my firm has endeavored to model initial embodied carbon. These numbers do not paint a complete picture as the data only represents the structure and envelope (in accordance with the required scope for LEEDv4)—missing are interiors, mechanical systems, and other components. But we’re starting to develop a frame of reference.
Figure 1: Predicted (modeled) embodied carbon intensity from five case study projects.
What good will modeling and reporting embodied carbon do?
By advancing a wide-spread effort by the AEC industry to track and report embodied carbon, we stand to benefit in the following ways:
- It will drive design innovation. As project teams become conversant with embodied carbon figures, modeling can more readily and effectively be leveraged as a design decision-making tool — much like that of building energy modeling.
- It will help the AEC industry develop an extremely helpful resource: a dataset from which we can start to make reasonably apt comparisons to other buildings. Wouldn’t it be great if we could develop a percentile-based metric such as the ENERGY STAR score? Such a metric could facilitate project benchmarking, policy, and building product optimization.
- It will give the AEC industry a basis upon which we can start to measure and verify initial embodied carbon. Building product transparency and the maturation of building information modeling (BIM) will lead us toward a day when we will be able to model predicted embodied carbon in our buildings and, after construction, verify a project’s embodied carbon based on as-built conditions.
Of course, the idealist in me knows that the only number that truly matters is “0” — a built project that through a combination of reuse and reconstitution of materials and resources can achieve true circularity and a net-zero embodied carbon intensity.
The end goal is a decarbonized built environment. But for now, let’s start tracking and reporting our predicted embodied carbon data — and start improving our processes and figures.