Embodied carbon and the construction industry’s role in reducing global carbon emissions Reducing Global Carbon Emissions.

BY MATTHEW ANTHONY Associate – Advisory at AECOM

The chances are that you are reading this article on an electronic device rather than in printed form. But which medium produces the least carbon emissions? You may firstly think the electronic device is the least sustainable way to read the article as it requires power to operate, so you may reasonably conclude that the printed matter is responsible for less carbon emissions, however, it is not as simple as that when you consider the embodied carbon. A study by Alma in Finland determined that it takes between 150-190kg of CO2e (carbon dioxide equivalent, the common scale for measuring the climate effects of different gases) to produce a newspaper or magazine. Apple, the producer of iPads on which millions of publications are read every day, claim that the total lifecycle emissions of a typical model is 130kg CO2e of which only 30% are associated with customer use (iPad Environmental Report, Apple). There are many factors that could influence these findings, such as where the energy is sourced for production and the use of sustainable materials. So, whilst these figures cannot be taken as absolutes, they do provoke holistic thinking about carbon emissions.

It is critical to drive and fly less, use less electricity, generate electricity from sustainable sources, recycle, and reuse where possible.

It also suggests that whilst the printed media may have zero ‘operational’ emissions, its carbon footprint can be higher than an electronic device. Turning this thinking to the built environment, we know that this sector has an important role to play in reducing global emissions. According to the World Green Building Council and the UN Environment Global Status Report, buildings are currently responsible for 39% of global emissions; 28% from operational emissions from energy required to heat, cool and power them and 11% from materials, construction and maintenance activity. These figures are not likely to decline either. As the world’s population continues to grow, the International Energy Agency predicts that the total global building stock will double by 2050. Plans for action achieving net-zero carbon emissions have been announced by governments and organizations worldwide. However, if these targets are going to be met, the embodied carbon responsible for 11% of global emissions from the construction industry alone must be understood, measured, and minimized where possible.

The lifecycle carbon impact of a building can be split into four stages: production, construction, operation and end-of-life. The production stage accounts for approximately 33% of a building’s carbon impact and includes the extraction of raw materials, transportation and manufacturing into buildings products. The construction stage accounts for a further 8%, and includes all construction activity, including transport of materials and labor to site, installation and commissioning. This means that before a building is ready for occupation, it has already incurred approximately 41% of the total carbon impact ‘upfront’. During occupation, we enter the operation stage where all direct emissions from energy consumption are incurred, accounting for around 42% of lifecycle carbon impact, with embodied carbon seen in maintenance, repair, refurbishment and asset replacement activity accounting for a further 11%. The remaining 6% of carbon impact is found in the end-of-life stage where demolition, waste processing and disposal is undertaken. The greatest potential for a reduction in the carbon impact of a project is therefore found not only in the operation stage, but in the design stage where upfront carbon can be reduced. Research by C40 Cities, Arup and the University of Leeds suggest ways in which a reduction in embodied carbon can be achieved and highlights the importance of switching to lower carbon materials and using materials more efficiently to reduce the upfront carbon incurred. This can only be substantially achieved with an understanding of a material’s embodied carbon, quantified by an embodied carbon assessment. More general practices during the design stage can be implemented, such as decreasing reliance on duplication in specifications and ensuring buildings are not over-specified either for intended loads or use.

There is currently a reliance on stated embodied carbon quantification from environmental information on the lifecycle of a product, for which a standardized Environmental Product Declaration (EPD) process has been outlined by the International Organisation for Standardization (ISO) in ISO 14025. However, there are several challenges with using EPDs, not least because they are constantly being updated as manufacturing processes and material selections change, resulting in complex and inconsistent databases. Further complications are found in the methodology for creating an EPD, which relies on the definition of the product using appropriate Product Category Rules (PCRs) that use Life Cycle Assessment (LCA) studies. LCA studies vary in terms of assumptions and considerations depending on the availability of data and can therefore lead to inconsistencies in comparing products that fulfil the same function. Factors such as location, production methods, supply chain conditions and lack of third-party review create additional inconsistencies in EPDs that see various databases being used and no clear benchmark data available.


Smoke and steam rising into the air from power plant stacks; dark clouds background; concept for environmental pollution and climate change

In the UAE, the Emirates Green Building Council (EGBC) is taking the lead in establishing working groups and raising awareness of embodied carbon in the construction industry, but they acknowledge there is a way to go. The EGBC Embodied Carbon Working Group has been formed to provide useful guidance to the industry with the aim that some legislation may follow to compel the sector to meet targets. While no specific legislation exists, the UAE National Climate Change Plan (2017-2050) and a recent declaration of UAE becoming a net zero carbon country by 2050 – the first Middle East country to make such an announcement – provides a framework to which the issue of embodied carbon cannot be ignored if these targets are to be achieved. The plan itself, which does not explicitly mention embodied carbon, positions the Ministry of Climate Change and Environment as leader in raising awareness in partnership with stakeholders to act. Perhaps the most exciting opportunity to incentivize embodied carbon reduction is found within project financing, where performance against sustainability goals influence the interest rates available and access to loans. Widely referred to as ‘Sustainability Linked Loans (SLL)’ and guided by principles such as those published by the Loan Market Association (Sustainability Linked Loan Principles, May 2021), these financial products reward borrowers for achieving pre-determined sustainability targets, which rely on the ability to measure, quantify and convey performance against them. This way of financing also meets the ESG demands of lenders who are under scrutiny for lending to fossil fuel industries. In the Middle East, Aldar Properties announced in July 2021 that they secured a 300 million AED SLL with HSBC linked to KPIs, becoming the first MENA company to do so.

Conversations around reducing our carbon impact are usually focused on emissions resulting from direct user activity. We all need to drive and fly less, use less electricity, produce electricity from sustainable sources, recycle and reuse where possible. However, the traditional focus on operational carbon reduction and a misunderstanding of the true impact of embodied carbon remains and needs to be addressed. Direct emissions from any built asset can be roughly equivalent to the embodied carbon incurred ‘upfront’ during the manufacturing and construction phase alone – and continue to be incurred throughout the asset’s lifecycle. The need for the industry to understand, measure and reduce embodied carbon to meet the demands of an informed client is therefore critical to the effort to reduce global carbon emissions if current targets are to be met. Raising awareness of the issue is just the first step