Carbon Counting: Why “Embodied” Carbon Matters (Part 1)

The title of this blog is unabashedly borrowed from one of the truly excellent panel discussions at the Façade Tectonics Institute’s (FTI) forum event in Seattle in July. As ever at FTI events, the quality and depth of dialogue on façade topics was second to none. The carbon counting panel, moderated by Kate Simonen from the University of Washington’s Carbon Leadership Forum, and including panelists Stacy Smedley from Skanska, Kjell Anderson from LMN Architects and Mic Patterson, co-founder of FTI, rang alarm bells and compelled me to dig deeper into this topic area to understand potential ramifications for the planet and our industry.

Operational vs Embodied Carbon

Until now, the thinking has been that the amount of carbon emitted during the operational lifetime of a building (operational carbon) far outweighed the carbon emitted during the manufacturing of the building’s materials and in its construction (often referred to as embodied carbon) (See Figure 1).

That has very appropriately created a focus primarily on improving the energy efficiency of buildings, and not on reducing the impacts caused by constructing the building in the first place. According to Simonen, the balance between the two is changing. With the improvement in energy efficiency of buildings, and the “cleaning” of our electric grids through the increasing use of renewable energy, the carbon emissions related to constructing buildings is becoming more significant.

As an example, at the FTI forum Smedley illustrated that, for a Seattle mid-rise building, a whopping 84% of the greenhouse gas (GHG) emissions over a 50-year operational period were derived from building materials and construction. Much of that has to do with the fact that Washington State’s electric grid is dominated (71%) by abundant hydro-electric power, and presumably many of the materials used were made elsewhere. A de-carbonized grid reduces the GHG emissions produced for each kilowatt hour of electricity used, significantly reducing building operational emissions. The GHG emissions involved in operating the same building in, say, Indiana or Utah today would be significantly higher because of their more carbon intensive electric grids, and so the example in Washington is likely “best case” today. However, the overall proportion of renewables powering grids is increasing nationally. In June, for the first time, electricity generation from renewables (23%) across the entire U.S. surpassed that from coal (20%).

Why Embodied Carbon Matters for the Planet

According to data from UN Environment, embodied carbon (emissions from the construction industry including materials manufacture) is responsible for 11% of global GHG emissions, and 28% is due to global building operational emissions (see Figure 2). Additionally, Architecture 2030 states “embodied carbon will be responsible for almost half of total new construction emissions between now and 2050.”

“Embodied carbon” is a rather inappropriate and misleading term since there is nothing “embodied” about this carbon. Quite the contrary, the carbon (in the form of carbon dioxide, CO₂) has been emitted during the manufacturing and fabrication processes and is living life in our atmosphere already contributing to climate change. Lloyd Alter suggests that embodied carbon should be renamed as “upfront carbon emissions” as it better reflects the immediacy of the fact that it is being emitted right now, and causing a real-time impact.

In a compelling article published by Canadian Architect, Anthony Pak argues that embodied carbon is the blind spot of the buildings industry. He discusses the concept of the time value of carbon, in which controlling the timing of the emissions is critical. He and many others assert that we have no time to waste in reducing “upfront carbon emissions” because:

• We need to curb carbon emissions, and fast: The United Nation’s International Panel on Climate Change (IPCC) predicts that the rate of carbon emissions needs to flatten by 2020 (yes, within 18 months) and reduce to zero by around 2055 to maintain global warming to 1.5 degrees Celsius and prevent a climate catastrophe.
• The rate of building construction is accelerating: The UN Environment 2017 Global Status Report states that energy efficiency improvements haven’t kept up with rising floor areas and predicts globally that building floor area will double by 2060. According to Ed Mazria of Architecture 2030, the global building floor area is estimated to grow by 40% in the next 15 years alone, which is the equivalent of replicating all the buildings already standing in the entire western hemisphere!
• There is (somewhat) more time to address operational energy emissions: Operational emissions are cumulative and can be reduced over time with improved retrofit technologies and transition to cleaner electric grids. “Upfront emissions” are locked in at the front end of the building’s lifetime and can’t be reduced later. This is especially critical given the rate of building growth in the next 15 years.

When asked during the Carbon Counting panel at the FTI forum, “What if we can’t afford to reduce carbon emissions in our building materials?” Mic Patterson answered soberingly, “What happens if we can’t?”

Next month, we’ll dig into the implications for the construction industry: What’s in environmental product declarations is going to matter much more, and where materials are manufactured may provide a distinct competitive advantage.