How is Concrete Getting a Green Message Across?

Global cement producer Cemex recently revealed that they are introducing the label Ecoperating for their products that feature an outstanding sustainability performance. Cemex developed this label “through a rigorous internal process that measures the environmental or social impact of a wide range of building solutions” in their portfolio.

Cement industry initiatives to properly characterize sustainability aspects of their cement offerings will be an interesting topic going forward. The cement and concrete industry face a distinct challenge. On the one hand, concrete is the most widely used building material. Its annual production far exceeds that of the next most widely used building material and its demand is only projected to increase.

Annual World Production of various industrial materials (From Ashby, Materials and the Environment: Eco-Informed Material Choice, 2012)

On the other hand, the production of concrete comes with a carbon cost because of the use of cement. One tonne of cement involves the emission (due to energy requirements and calcination) of around 650 kg of carbon dioxide (if we assume a typical clinker loading in cement of about 75%). This carbon footprint presents a distinct issue to overcome when properly framing the environmental impact of concrete. Even further, this footprint is problematic in comparison to that of, for example, wood. From a material perspective it is apparent that the wood and timber industry representatives have been far better at expressing the “green message” than have been the cement and concrete industry.

In this light, to properly assess concrete in a sustainability context requires a consideration of the energy intensity of various materials. While cement may have a significant carbon emission profile, concrete typically only contains 6 to 10% cement by mass. By that consideration, concrete consequently compares very favorably to other building materials and ends up with a very low embodied energy per unit volume.

Embodied Energy Per Unit Volume of Material (From Ashby, Materials Selection in Mechanical Design, 2010)

Despite the fact that life cycle assessments of concrete show that it is a building material with a longer lifespan, a greater thermal mass than alternatives and that it can be recycled (ground concrete can be reused as an aggregate in the production process), the industry has not communicated its benefits very well. Perhaps one of the reasons is that current LEED assessments of building materials (pre LEED v4) have had gaps insofar as cement industry actions to offer lower carbon intensity products were not adequately recognized. This lack of being able to craft the right ‘sustainability message’ has created grave shortcomings for the cement industry, particularly as we recall that concrete is the most popular building material and is being used about an order of magnitude greater more than either steel or wood.

The cement industry has three realistic avenues to reduce the carbon intensity of cement (and thereby improve the sustainability profile of concrete). These are:

  1. Thermal and electrical efficiency - Deploy best available technology in new cement plants (while pursuing retrofits where economically viable) to lower the energy requirements for producing cement.
  2. Alternative fuels - Use less carbon-intensive fuels and more alternate fuels & wastes to supply the energy for cement production.
  3. Clinker substitution - Substitute clinker with other low carbon materials with cementitious properties.

To contextualize these efforts, currently clinker substitution can help achieve LEED points by speaking toward the use of recycled content, yet other cement/concrete industry carbon intensity levers would not fall under the current LEED points system (i.e. points 1 and 2). However there is the very realistic chance that future versions of LEED (with LEED v4 currently being developed) can more accurately reflect the reality of environmental efforts within the cement and concrete industry.

This brings about a very interesting notion, which is that with a greater carrot dangling before the cement/concrete industries, they are even more likely to invest in sustainable solutions or promote other impactful offerings. This could equate to a similar effect that the forestry industry saw when LEED recognized it as the only specific building material in the entire rating system.

For the current accreditation landscape wherein concrete is not well addressed within the LEED system, industry efforts to highlight green products/efforts seem to be aligning well with other green building certification and listing formats. Some examples relevant to concrete producers include:

Such certifications may be more niche that an overall LEED designation. However, they would currently be more suitable for properly fitting concrete into the incredible breadth of building projects that pursue green measures on an ad hoc basis as opposed to pursuing a full LEED designation. Pushing a sustainability message through these other channels can certainly be a fruitful effort for cement and concrete producers.

For the cement/concrete industry to get a green message out it will take many approaches. The in-house effort of the Ecoperating label is a display of initiative from Cemex. Third-party sustainable building material accreditation programs are an important second channel. Down the road, the industry can be optimistic that LEED v4 will more adequately reflect the realities of concrete as a green building material. The message will find a way.

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