Last week the US General Services Administration (GSA) announced that it was investing US$2bn on over 150 construction projects that use low-embodied carbon (LEC) materials. The funding is intended to support the use of US-manufactured low carbon asphalt, concrete, glass and steel as part of the Inflation Reduction Act. For readers who don’t know, the GSA manages federal government property and provides contracting options for government agencies. As part of this new message, it will spend US$767m on LEC concrete on federal government buildings projects following a pilot that started in May 2023. The full list of the projects can be found here.

This is relevant because the US-based ready-mixed concrete (RMX) market has been valued roughly at around US$60bn/yr. One estimate of how much the US federal government spent on concrete was around US$5bn in 2018. So the government buys a significant minority of RMX in the country, and if it starts specifying LEC products, this will affect the industry. And, at present at least, a key ingredient of all that concrete is cement.

This isn’t the first time that legislators in the US have specified LEC concrete. In 2019 Marin County in California introduced what it said was the world’s first building code that attempted to minimise carbon emissions from concrete production. It did this by setting maximum ordinary Portland cement (OPC) and embodied carbon levels and offering several ways suppliers can achieve this, including increasing the use of supplementary cementitious materials (SCM), using admixtures, optimising concrete mixtures and so on. Unlike the GSA’s approach in November 2023 though, this applies to all plain and reinforced concrete installed in the area, not just a portion of procured concrete via a government agency. Other similar regional schemes in the US include limits on embodied carbon levels in RMX in Denver, Colorado, and a reduction in the cement used in RMX in Berkeley, California. Environmental services company Tangible compiled a wider list of embodied carbon building codes in North America that can be viewed here. This grouping also includes the use of building intensity policies, whole building life cycle assessments (LCA), environmental product declarations (EPD), demolition and deconstruction directives, tax incentives and building reuse plans.

Government-backed procurement codes promoting or requiring the use of LEC building materials for infrastructure projects have been around for a while in various places. The general trend has been to start with measurement via tools such as LCAs and EPDs, move on to government procurement and then start setting embodied carbon limits for buildings. In the US the GSA’s latest pronouncement follows on from the Federal Buy Clean Initiative and from when California introduced its Buy Clean California Act in 2017. Outside of the US similar programmes have been introduced in countries including Canada, Germany, the Netherlands, Sweden and the UK. On the corporate side members of the World Economic Forum’s First Movers’ Coalition have committed to purchasing or specifying volumes of LEC cement and/or concrete by 2030. Examples of whole countries actually setting embodied carbon emissions limits for non-government buildings are rarer, but some are emerging. Both France and Sweden, for example, introduced laws in 2022 that start by analysing life-cycle emissions of buildings and will move on to setting embodied carbon limits in the late 2020s. Denmark, Finland and New Zealand are also in the process of introducing similar schemes. The next big move could be in the EU, where legislators are considering embodied carbon limits for building materials as part of its ongoing revisions to its Energy Performance of Buildings Directive or the Construction Products Regulation legislations. Lobbying, debate and arguing remains ongoing at present.

To finish, Ireland-based Ecocem spent a period in the 2010s attempting to build a slag cement grinding plant at Vallejo, Solano County, in the San Francisco Bay Area of California. The project met with considerable local opposition on environmental grounds and was eventually refused planning permission. The irony is that slag cement is one of those SCM-style cements that Marin County, also in the San Francisco Bay Area, started encouraging the use of just a few years later. Ecocem held its inaugural science symposium in Paris this week. A number of scientists who attended the event called for existing low carbon technologies to be adopted by the cement and concrete sectors as fast as possible. One such approach is to lower the clinker factor in cement through the use of products that Ecocem and other companies sell. A point to consider is, if Marin County’s code or the GSA’s recent procurement directive came earlier, then that slag plant in Vallejo might have been built. Encouraging the use of LEC building materials by governments looks set to proliferate but it may not be a straightforward process. Clear and consistent policies will be key.