Displaying items by tag: Life Cycle Assessment
Building codes and low-embodied carbon building materials
15 November 2023Last 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.
France: Hoffman Green Cement Technologies, a pioneer in low-carbon cement production, has announced the publication of its Life Cycle Inventories (LCI) in the INIES database, France’s national reference database for environmental and health performance in the construction sector.
The LCI published by Hoffmann Green summarises all incoming and outgoing flows of raw materials and energy resources used to manufacture its H-UKR and H-EVA cements to allow an assessment of the environmental impacts. They will serve as input data for the software that carries out the life cycle analysis of a construction product, often comprising several materials.
H-UKR is a binder that is based on alkali-activated blast furnace slag, which is sold into the precast concrete, ready-mix concrete and bagged cement markets. H-EVA is a high ettringite binder that is used in the mortar, coatings, road binder and ready-mixed concrete markets.
Julien Blanchard and David Hoffmann, the company’s founder’s stated, "The publication of the LCI of our cements is a first in France and is part of our determined ambition to decarbonise the construction sector and be fully transparent vis-à-vis all our stakeholders. It also illustrates our commitment in the face of the climate change emergency and the need to reconcile cement and the environment.”
Building materials as a service
15 January 2020Here’s a fun idea: providing building materials as a service. Instead of the owner of a building possessing all the materials in it forever, they simply rent them. It would be like a music or television streaming service. A ‘Netflix’ or ‘Spotify’ for the construction industry. ‘Rentacrete’ if you will…
The Guardian Cities series has been discussing the idea this week in a feature on whether buildings should be demolished at the end of their lifetime. The feature largely looks at the ideas of Dutch architect and commentator Thomas Rau, the author of Material Matters. He talks about his ‘materials passport’ concept whereby all the materials in a building are logged with their properties to highlight their value when the structure is demolished. This is a refinement of the Building Information Modelling (BIM) system. Rau has put his passport premise into action for a couple of projects through his firm and the Madaster Foundation promotes its use.
The next steps that he envisages are buildings where the materials that constitute it are simply rented from the manufacturer. Since the material owners would now become companies they would have an interest in efficiency where the materials can be refitted, such as lighting, and/or recycled for when the building is torn down. In Rau’s view these companies would be in a better position to recoup the value of these materials when a building is demolished. He estimates that 18% of a building’s original construction cost can be preserved in this way. Suddenly, sustainability becomes much easier by changing one’s perspective on who owns what exactly in a building.
How this idea would work in practice raises all sorts of questions. For example, most buildings in the developed world last for as least as long as humans do. Which companies could be relied on to hang around this long? Building materials as a service might work for soft materials that are replaced more often, such as lighting and other interior fittings, but could this extend to a structure’s shell? One answer to this is that people invest in pension schemes and use banks quite happily over long periods time, so why not a building’s very fabric? Another issue is of liability and whether a manufacturer would want to take on additional responsibilities for its products decades later. This, and the idea in general, have similarities to the extended product responsibility strategy. Obviously someone needs to try out building materials as a service for real to tackle these questions and many more.
Building materials as a service is compelling but one reason that the construction industry has proved resistant to the digital revolution across the entire business, so far, is because it ultimately deals with physical products that people need permanently. Consumer digital renting services for media, like Netflix and Spotify, are ‘disposable’. Hence, the mindset is different. That’s not to say that building materials as a service is impossible just that it is a harder shift in thinking. A country with a high level of residential renting, for example, might find it easier to move to this model than one with high levels of home ownership.
One more thing to consider is that the media renting companies mentioned above are dependent on other companies producing the content. Due to this they have moved towards vertical integration as the producers themselves, notably Disney in 2019 which has started to set up its own online rental platform. The point here being that in a product rental environment, whoever produces the product, holds a large amount of influence. Building materials manufacturers take note. Building materials as a service might just be a talking point on the lecture circuit along the road towards sustainability in the construction industry. Yet if it did happen at any scale then the producers of concrete, mortar, bricks, steel and all the rest would be well placed to benefit from it.
US: Researchers from CalPortland have published a peer-reviewed study looking at the absorption or carbonation of CO2 by buildings, pavements and structures made from concrete. The authors argue that this negative effect on CO2 emissions is not being considered in global, national and regional greenhouse gas accounting methods. The paper calls for focused studies on CO2 uptake in concrete within the context of its overall Life Cycle Assessment (LCA).
“It is time to further examine the value of concrete in the built environment as a significant carbon sink,” said Allen Hamblen, president and chief executive officer (CEO) of CalPortland. “To do so accurately, we must specifically look at the net effects of CO2 sequestration in concrete and evaluate all structures over their lifetime within a circular economy.”
The study looks at previous attempts to quantify the effect of concrete carbonation, notably using work by the Swedish Environmental Research Institute (SERI) that examined data from several European countries to develop practical models to gauge the extent of CO2 uptake by concrete globally in the built environment. Different models estimated that 15 - 20% of CO2 emissions from clinker production were reabsorbed over the lifetime of concrete structures.