Addressing concrete’s carbon footprint – Irish Concrete Federation
CONOR HAYES, Head of Sustainability, Irish Concrete Federation, speaks with Robbie Cousins about how its members are working to reduce carbon emissions from cement and concrete products.
Concrete, a cornerstone of human civilisation, has shaped our world from ancient times. This versatile material underpins our cities, roads, and bridges, driving societal progress and urban development. As the second most consumed material globally, after water, concrete’s ubiquity is undeniable.
However, this essential building block has come with a significant environmental cost. Cement and concrete production is responsible for approximately 8% of global CO2 emissions, underscoring the urgent need for innovative solutions to reduce its carbon footprint.
At COP28 in Dubai in 2023, countries committed to a bold new programme, the ‘Cement and Concrete Breakthrough’ initiative, aimed at the widespread adoption of near-zero-emission cement production by 2030.
The Irish Concrete Federation’s (ICF’s) Head of Sustainability, Conor Hayes, says that cement and concrete producers are making considerable advances in addressing carbon emissions relating to their products and working with other industry stakeholders to identify ways in which the essential building material can be used in a less environmentally impactful way, while at the working on solutions to develop near-zero emissions cement.
IRISH CONCRETE FEDERATION
The ICF is the national representative body of the Irish aggregates and concrete products industry. It represents 74 members and associate members operating at approximately 300 locations across Ireland. ICF members comprise publicly listed and family-owned businesses, including quarry operators. These companies produce essential building materials such as aggregates, ready-mixed concrete, precast concrete products and agricultural lime.
Conor Hayes has been working with ICF members and industry stakeholders to address the carbon emission impacts of concrete, a material that he says has a lot to offer in terms of reducing emissions when specified and used in the correct way. Hayes has had a career-long fascination with the sustainability of construction materials.
“Before joining the ICF, I worked for 17 years as a structural engineer with Arup, operating primarily between their Dublin and London offices and working on various projects in other parts of the world.
“I became fascinated by materials sustainability as a young engineer when a client on a large and complex project in the Middle East raised the issue. This opened up a new area within engineering, leading to my completing a master’s thesis in Materials Sustainability in the Design Process. Through this, I gained a greater understanding of the materials used in construction and how they affect the embodied carbon and the whole-life carbon (WLC) of buildings and structures. As my career progressed, I carried out WLC assessments of Arup projects and provided clients with WLC options in terms of project design for elements such as facades, structures, finishes, MEPs, etc.
“I was later appointed to a global structural sustainability role within Arup and was a member of their global carbon steering group. The steering group looked at the decisions that designers made around sustainability and the impact that these had on carbon, biodiversity and circularity. I helped establish a structure within Arup to assist designers in working with sustainability in mind, allowing them to specify and engage with contractors around this issue and, in turn, encouraging contractors to engage with their supply chains to track sustainability through the entire construction process.”
MAKING CONCRETE SUSTAINABLE
When the ICF came calling earlier this year, Conor Hayes says he wasn’t going to pass on the opportunity to work with the biggest supply chain in the industry.
One of the issues he is addressing as ICF head of sustainability is engaging with ICF members and industry stakeholders on how cement and concrete can be utilised in more sustainable ways.
He explains: “Designers can only specify what is available to them. Likewise, contractors can only use the materials available through their supply chain. Understanding how the cement and concrete supply chain works and the constraints it operates under is fundamental to clients’ abilities to achieve the embodied carbon goals of their projects.
“I have come to understand that when the carbon intensity of concrete is compared with other construction materials, it will perform very well under the right conditions. Many elements contribute to the embodied carbon in a project. If you assess what happens to any building material from the point of extraction to when it is used, quite a few factors contribute to the emissions associated with it. And while there are a lot of emissions associated with cement production, the key ingredient in concrete, huge advances are being made by the industry to reduce these.”
He adds: “From conducting WLC assessments, I came to understand that concrete is not necessarily unusually carbon intensive compared to other construction materials. In fact, in many cases, its intensity is lower. Obviously, this outcome is impacted by project decisions- and context-specific issues.
“And let’s not forget, concrete is the second most used substance on earth after water. It is an incredibly useful material. It’s robust, durable and cost-effective. It’s formable and has good vibration, acoustic and fire resistance performance. “The challenge with concrete is not that the amount of carbon per kilo or a metre cube is incredibly intense. The problem is that as we need to use so much of it, we have to rethink how we use it in a sustainability sense.”
REDUCING CONCRETE’S CARBON INTENSITY
A large proportion of the world’s carbon emissions are related to cement used primarily in concrete. The challenge is to reduce emissions associated with concrete, and Conor Hayes says the industry is working on this.
“The seemingly obvious solution is to replace concrete with less carbon-intensive materials. But, alternative materials are just not suitable for the purposes that concrete is used for. I concluded long before I joined ICF that as the industry is so dependent on concrete, we must find ways to reduce carbon intensity directly.
“ICF members have embraced the numbers around cement and concrete and understand where the environmental impacts are with their products. Manufacturers are working with clients, designers and contractors to provide options for better carbon outcomes.
“When we engage with the design community, we often see elements that are, for example, over-specified, such as exposure classes where a project ends up using more cement than is needed.
“The ideal for concrete products in their current form is to use less volume of concrete., use less cement in that concrete, and use less clinker in that cement. Contrary to being a threat to the industry, ICF members are embracing these issues and coming up with solutions.”
NEXT STEPS
Conor Hayes says the goal is to get to a point where carbon content can be properly measured and that measurement is validated, then produce EPDs and communicate the significance of the information contained therein to clients and stakeholders.
On the precast side, he explains that there are several additional steps that can be taken. “For example, precasters are optimising mixes with respect to carbon. When I first started working as an engineer, nobody was optimising their designs or concrete mixes for carbon, but substantial savings are being achieved by doing this.
Hayes adds that, to date, there has been a lot achieved by the cement industry in reducing emissions. Measures include reducing clinker content and using alternative fuels in cement plants. “The long-term opportunity is to capture carbon and store it. There are also opportunities for alternative binders and cement replacements on the horizon.
“There’s been a lot of use of GGBS and PFA generally. But both of those materials will become less available over time. So the industry has to develop other replacements and binder products that will reduce the use of Ordinary Portland Cement (OPC) in concrete.”
He continues: “There’s also designed-in solutions such as using more efficient forms. We can also look at other performance requirements around loading and durability to give the industry what it needs rather than simply supplying an excellent and durable product.”
POINT-SOURCE CARBON CAPTURE
The heating of limestone to produce clinker accounts for 50% of emissions in cement production. Various alternative fuels are at different levels at gestation. Conor Hayes says the use of alternative fuels in cement plants is moving forward at a great pace, with up to 70% plus in some processes, and he suggests this percentage could go as high as 90%.
“The use of alternative fuels has been gradually increasing and will continue to go up. However, cement producers have also been working on other thermal efficiency measures, whereby they are looking to get a better bang for their buck in terms of the heat that they are putting into the calcination of limestone.”
Point-source carbon capture, where CO2 from large sources such as power plants and industrial facilities is trapped and stored to prevent it from being released into the atmosphere, is a key method for cutting emissions in the cement and concrete industry. Hayes explains there have been promising trials with carbon capture and storage within concrete. “One of our members offers a product that uses captured carbon in the wet mix. The primary benefit is that this accelerates strength gain, and thus less cement is needed.”
CLINKER MANDATE
The ICF welcomed the government’s Clinker Mandate earlier this year. The mandate specifies a minimum of 30% clinker substitution in concrete products used in government and public works projects.
He comments: “We engaged with the team that prepared the report which brought about the mandate, and we appreciate where they are coming from in terms of setting out a roadmap for how the industry will change and how it needs to change.
“The mandate is an important signalling exercise to the sector, and we have taken that signal on board. Our industry has long moved from CEM1 to CEM2 cement mixes, with significant replacement in some industry sectors.”
WORKING WITH OTHER BODIES
The ICF is a member of the Irish Green Building Council (IGBC) and works with Construct Innovate and the Construction Industry Federation (CIF).
Conor Hayes notes: “These bodies do excellent work, and we would be delighted to get the opportunity to work with them. There is a lot of scope for R&D in the industry and tremendous opportunities for Ireland in terms of being at the forefront of construction R&D.”
BIODIVERSITY
ICF members who operate quarries play a significant role by having a net positive impact on biodiversity. Through the nature of their operations, they are ideally placed to support birds of prey, such as peregrine falcons and buzzards, who nest in unused quarry faces. In addition, operators are rewilding the lands around their quarries with native woodland.
Conor Hayes explains: “Our quarry members are creating distinct, new biodiverse habitats. You’ll often see birds of prey, peregrine falcons, buzzards, and so on, nesting in quarries and being left alone in a way that would not necessarily be the case in surrounding farmlands. Quarry practices introduced in recent years include not cutting into certain faces during nesting season.
“In addition, many quarries have rewilded around their space, as they want to bound off quarry operations for safety and security purposes. They’ve often planted native woodlands all around their land that then go untouched.
“Furthermore, once a quarry has been exhausted, the owners remediate it, sometimes by taking in waste soil and stone from projects elsewhere.”
IN CONCLUSION
The main challenge facing the cement and concrete industry is reducing CO2 emissions while at the same time meeting massive demand. Conor Hayes believes that addressing climate change in the built environment will require every stakeholder to contribute.
“We all know that reducing carbon emissions in construction must involve every stakeholder and every step in the construction process from concept to end of a building’s or structure’s life cycle. Reducing emissions is not simply a concrete or a cement problem. We all need to work together in a sensible, consistent and numerical way to find solutions.
“ICF members understand that they have a responsibility because of the sheer scale of the material’s use. We are working extremely hard to address the issue. And we want to engage with all stakeholders, including other materials producers, to deliver a more sustainable built environment,” Conor Hayes concludes.