Embodied Carbon

The California Construction and Industrial Materials Association (CalCIMA) supports the responsible implementation of embodied carbon policy. The largest contribution to embodied carbon in concrete is cement which will be managed under recently passed SB 596. This discusses remaining locally produced construction materials made of earthen materials produced from our working lands.

Construction aggregates, a locally-produced commodity, receives its embodied carbon largely from the electricity that is used to crush, grind and convey the mined materials around a site for processing. In addition, the fuels used in the equipment to extract or move the materials around the site contribute. As such, California is already aggressively reducing the embodied carbon in domestically-produced construction aggregates from the energy served on the grid, the fuels utilized to produce and move the materials, and through the regulation of equipment and vehicles. 
Local producers will be expected to account for carbon in their de minimis contribution towards the embodied carbon in concrete and asphalt, or the state could consider developing or embracing regional indices.

Asphalt is a ubiquitous paving material composed of construction aggregates bound together with asphalt binder. Asphalt typically consists of approximately 95% construction aggregates and 5% asphalt binder. The dominant additional embodied energy added to asphalt, above that derived from the production of construction aggregates, results from the embodied carbon in the asphalt binder and the energy necessary to heat the aggregates and binder. California and CalCIMA aggressively support the use of recycled materials and sustainable best practices in the production and placement of asphalt mixtures including:
  • The use of Reclaimed Asphalt Pavements (RAP)
  • Recycled Asphalt Shingles (RAS)
  • Ground tire rubber (rubberized asphalt)
  • The use of Warm Mix Asphalt (WMA) technologies.
The use of recycled materials and warm mix asphalt technologies offers significant opportunities to reduce the embodied carbon emissions associated with the production, transportation and placement of asphalt. California asphalt producers currently use natural gas, state-of-the-art efficiency burners including Exhaust Gas Recirculation (EGR) systems to heat and combine the aggregate and asphalt binder. For now, technologies do not exist to have an electric asphalt plant, but electric heating solutions do exist for asphalt binder tanks and storage silo heaters which are largely implemented in California. The embodied carbon in natural gas fuels could be managed through the availability of renewable natural gas for these manufacturing activities.

Portland cement concrete is both a building and paving material which is composed of construction aggregates bound together with cement activated by water. While the ratios vary based on the desired performance characteristics of the concrete, in general, a cubic yard of concrete 10-15% cement, 60 to 75% construction aggregates and 15-20% water. Approximately 90% of the embodied carbon in concrete comes from the cement with the remaining embodied carbon coming from the construction aggregates and water.
  • It is generally recognized that reducing embodied carbon in concrete is dependent primarily on reduction of embodied carbon from the cement component of concrete. This is occurring through:
  • The use of Portland Limestone Cement
  • The use of Supplementary Cementitious Materials (SCM’s)
  • Expand with the development of new cements or supplemental materials
  • Recycling of concrete materials, whether re-batching returned plastic concrete or reusing aggregate from returned concrete
While SCMs are not new, the supply of SCMs can be problematic since they come from outside California. Producers, therefore, are not configured to use SCM’s at every manufacturing plant as it requires storage silos, conveyors and additional infrastructure investment. In addition, the development of mixes using SCM’s and assistance with the development of environmental product declarations (EPD’s) so as to demonstrate reductions will likely be important for producers.

Life cycle analysis is an accounting system used to model the carbon emissions (and other impacts) associated with an activity. The construction and industrial materials industry believes life cycle analysis, properly implemented, is critical to incentivizing manufacturers to adopt embodied carbon reduction capacity into their manufacturing processes, reducing embodied carbon emissions for all consumers. Life cycle analysis comes in many forms and the CalCIMA supports cradle-to-gate life cycle analysis for plant- and product-specific embodied carbon measurement as well as cradle-to-grave life cycle analysis for comparisons between material types when modeled to the built environment. We believe these are the proper ways to measure and evaluate materials and the built environment.

Using cradle-to-gate measurement lets one isolate manufacturing process efficiency and product design and is effective for the comparison of like materials. Through measuring and encouraging this type of life cycle analysis, we incentivize manufacturers to invest in change; it is ideal for comparisons between like materials. Further, it ensures the entity investing in manufacturing improvements may be eligible for offsets generated.

Cradle-to-grave analysis is the proper way to analyze and compare two different types of material in the built environment. It allows for modeling the embodied carbon of building, operating, and decommissioning infrastructure, homes, and other constructed facilities with the different possible construction materials. It enables the full comparison of carbon emissions from the activities through the entire life cycle of the material (Production, Construction, Use, End-of-Life) creating a fair model of the full lifecycle carbon impacts in each material used. This makes it a suitable model to determine which type of material is better for which uses should one want to ensure the claimed carbon reductions are real vs measuring to a position in the life cycle most favorable to a particular material.
Cradle-to-grave measures society's full carbon footprint for building, operating, and decommissioning a desired amenity (dam, school, home, freeway, etc.) while Cradle-to-gate measures the full manufacturing cycle of a specific material. They are also a very useful measurement point. The manufacturer has control of the product through their gate and up to that point may operate to reduce embodied carbon to the extent feasible. An entity designing a project is, at that point, deciding what emissions will be embodied in that project or development over its useful life. When we use those measurement points we can manage those items for their embodied carbon.

Additional Policy Consideration

As producers of low value bulk commodities that serve as the foundation of the California infrastructure and manufacturing economies, we would like to point out that the state seems to be doing little thinking about the regressive nature of carbon cost on vital sectors of the economy and its potential impacts on people. As the state begins to regulate and legislate embodied carbon in our main street economy, we encourage the state to do what it can to mitigate costs and maximize opportunities for main street manufacturers to receive the full bonus of their investment. For now, California is racing down a path that will likely result in regressive cost imposition at the foundation of the economy. This seems likely to even further disadvantage local businesses in the State as well as cause unnecessary inflation for consumers.

Actions to Facilitate Producer Reductions (Authorizing & Incentivizing)

When the visible hand of policy is reengineering civilization, we believe it is time for it to also act to augment the invisible hand of the market in support of producers and consumers. Construction material producers will need society’s assistance to effectively and efficiently reconfigure manufacturing plants to provide the materials desired. These producers have ongoing significant expenditures coming in the form of equipment, vehicles and facilities that will be additive to any additional obligations placed in measuring or reducing embodied carbon. They will also need to make significant investments in data systems to validate reductions are real and defensible, and they will need to redesign and change their products while maintaining market acceptance. There is as much of a clear role for society to support producers in achieving the goal as there is in directing it be achieved.
The construction and industrial material producers of California take our obligation to reduce embodied carbon emissions seriously and accept the challenge of doing our part to become a net-zero society by 2045. We believe it is critical that policymakers support local manufacturers as well as main street businesses in these activities while protecting manufacturers' investments in carbon reduction from being claimed by others. Proper use of life cycle analysis is critical to this goal.