How Much Carbon Can Construction Materials Store?

  • Author(s)
    Jay H. Arehart, Francesco Pomponi, Bernardino D’Amico, Wil Srubar III
Bernardino D’Amico
Francesco Pomponi
Jay Arehart
Wil Srubar III

It has been well established that the built environment is a significant contributor of greenhouse gas emissions as a result of the production of construction materials and the energy consumed during operation. Yet, some construction materials, such as timber products and fast-growing grasses, have the ability to store carbon. A new paradigm has begun to emerge that evaluates buildings not only for their life cycle cabon emissions, but also for their potential to store and sequester carbon when these materials are used. The transition post-carbon cities will require the use of carbon storing materials because of their reduced life cycle carbon emissions. The present work provides a review of carbon storing materials with a focus on quantifying their ability to store or sequester carbon for inclusion in life cycle assessment. Focus is paid to two classes of construction materials: cementitious materials, and materials derived from biogenic carbon. Cementitious materials include concretes and mortars which store carbon through a chemical carbonation reaction. Biogenic materials are further classified based upon their harvest cycle length. Fast-growing materials (e.g., straw and hemp) are those that have a harvest cycle of less than 1 year, while slow growth materials (e.g., timber) have harvest cycles longer than 1 year. The storage potential of each material is considered from the perspectives of traditional, static life cycle assessment in addition to dynamic life cycle assessment. This review of carbon storing construction materials will provide building designers the tools necessary to quantify the carbon storage potential of buildings. By understanding not only the emissions of construction materials, but also their potential to store carbon, the paradigm of buildings as a carbon sink can be further developed and adopted by the architects, engineers, and urban planners.

this is a great project idea, I wonder how much you were able to quantify yet; it looks like lumber, hemp etc. and I guess you can do an easy comparison with the static LCA- not so much with the dynamic one, but this would be super exciting i think. And how this work will feed into design and construction practices is the next step ie. BREEAM or the like. you may also want to have a look at the BioHub we have at Newcastle for some inspiration- once the lock down is over you could visit us.

This is a good project. How fast could these materials absorb CO2? I am not sure whether the dynamic LCA works here.

We are currently working on a systematic review paper that will consider more materials (should be in print later this Fall).

Yes - comparison of dynamic LCA results to static ones is difficult, with GWP_bio being a go-between hybrid metric.

I think the building LCA community has had difficulty considering biogenic carbon in its accounting, so yes, hopefully the methodology can be incorporated into standards and practices.

Thank you for the invite Oliver - will reach out when the restrictions subside.

KK - In terms of rate of absorption, the bio-based materials absorb the CO2 before they are used in buildings, whereas the cementitious materials absorb carbon after construction, with a diffusion coefficient ranging between 4 mm yr^-0.5 and 19 mm yr^-0.5. While this may seem negligible at first, there are so many cementitious materials in the world that the uptake is estimated to be at nearly 1 Gt/year scale.