This article explores the nature of embodied carbon, where it is found in the built environment and how it can be measured, documented and reduced with reference to current initiatives, tools and examples in the construction industry.
The chances are that you are reading this article on an electronic device rather than in printed form, such as a magazine or journal. But which medium produces the least carbon emissions? Straight away you can differentiate the two by the fact that an electronic device requires a power source, such as a battery charged by electricity to operate. The magazine or journal though does not, so you may reasonably conclude that the printed matter has 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 are 130kg CO2e of which only 30 per cent are associated with customer use (iPad Environmental Report, Apple). Clearly there are many factors at play that could influence these findings, such as where the energy is sourced for production and use of sustainable materials. Although these figures cannot be taken as absolutes, they do provoke holistic thinking to carbon emissions and suggest that while the humble magazine or newspaper may have zero ‘operational’ emissions, its carbon footprint can be higher than an electronic device.
Turning this thinking to the construction industry and the built environment, we see the clear importance this sector has in reducing global emissions. According to the World Green Building Council and the UN Environment Global Status Report, of all emissions produced from all human activity worldwide (including printing newspapers and manufacturing iPads), buildings are currently responsible for 39 per cent: 28 per cent from operational emissions from energy required to heat, cool and power them, and 11 per cent from materials, construction and maintenance activity. These figures aren’t likely to decline either. As the world’s population continues to grow, the International Energy Agency projects that the total global building stock will double in size by 2050. Numerous plans for action have been announced by governments and organisations worldwide on how they will achieve net-zero carbon emissions over the coming decades, with an obvious focus on reducing operational emissions. However, if these targets are going to be met, the embodied carbon responsible for 11 per cent of global emissions from the construction industry alone must be understood, measured, and minimised where possible.
Embodied carbon in the built environment
In the context of the built environment, embodied carbon accounts for approximately 58 per cent of all emissions of a building, with the remaining 42 per cent associated with operational energy use. 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 per cent of a building’s carbon impact and includes the extraction of raw materials, transportation and manufacturing into building materials and products. The construction stage accounts for a further eight per cent of a building’s carbon impact and includes all construction activity, including transport of materials and labour to site, installation and commissioning. This means that before a building is ready for occupation it has already incurred approximately 41 per cent of the total carbon impact ‘up front’. During occupation, we enter the operation stage where all direct emissions from energy consumption are incurred, accounting for up to 42 per cent of lifecycle carbon impact, with embodied carbon seen in maintenance, repair, refurbishment and asset replacement activity accounting for a further 11 per cent. The remaining six per cent of carbon impact is found in the end-of-life stage where demolition, waste processing and disposal activity is undertaken.
The greatest potential for a reduction in the carbon impact of a project is therefore found within the design stage. Research by C40 Cities, Arup and the University of Leeds suggest some key 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 functionality.
An additional stage beyond the lifecycle of a building that includes recycling and reuse of materials can also be considered, but is not usually included in an embodied carbon assessment. However, as attempts to standardize measurement of embodied carbon continue, this is becoming a point of contention with some suppliers of materials and products that have high reuse or recycling potential that would offset otherwise high carbon impacts from production.
The challenges of measuring embodied carbon
Key to understanding the embodied carbon within a project is attributing the CO2e to a product or material specified for it. This is usually expressed as a rate per unit of said product or material. 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.
Progress is being made by private companies and non-government organisations to collate as much data as possible to ensure EPD databases evolve and become more robust. This is while attempting to standardize the way in which embodied carbon assessments are undertaken. The Royal Institution of Chartered Surveyors (RICS) has taken the lead in developing procedures for their members, recognizing their role in the industry and the impact surveyors can have in facilitating carbon reduction strategies. Publishing a mandatory practice statement for members, the Whole Life Carbon Assessment for the Built Environment, in 2017, they provided a methodology for calculating embodied carbon throughout the built asset’s lifecycle and prescribed acceptable sources of carbon data. This followed their information paper published as early as 2012 in support of the whole life analysis of the construction lifecycle (Methodology to Calculate Embodied Carbon of Materials Information Paper IP 32/2012, first edition). Unfortunately, the carbon data is still reliant on the EPD system, and while a database of EPDs in the UK has been developed to produce the RICS Building Carbon Database in 2019, this is still evolving.
The development of embodied carbon measurement tools
Developing embodied carbon measurement tools, just like the databases on which they rely, is an ongoing process. There are already several tools available to measure embodied carbon, such as Carbon Designer, EcoCalculator and EC3. However, Carbon Designer and EcoCalculator are limited to early phase modelling, whilst EC3 places strong reliance on EPDs. Indeed, EC3 has been developed specifically to address the significant variances in EPD data by providing results as ranges, rather than absolute numbers, whilst at the same time acknowledging its limitations through lack of available data.
As part of their Sustainable Legacies initiative, AECOM have utilised the advances in carbon data and database development to produce their own embodied carbon assessment tool. Known as ScopeXTM, the tool has been developed with the intention of helping architects and engineers understand the carbon impact of their projects, allowing clients to identify where reductions in embodied emissions can be achieved. While targeted for projects in their design stage, it can also be applied to existing buildings considering refurbishment. In the Middle East, AECOM’s Asset Advisory team are developing this tool further to work alongside their cost management teams, incorporating embodied carbon assessment into a wider lifecycle cost analysis using regionally specific data and location factors. It is intended that this tool will be adapted to all geographies in which AECOM operates, helping to deliver real reductions in CO2e around the world, from multiple projects where AECOM are engaged as a consultant, project manager, designer or engineer. Elsewhere in the Middle East, Majid Al Futtaim Properties, a leading developer, owner and operator of built assets, have also developed their own in-house tool for embodied carbon measurement with reference to the methodologies published by the RICS.
Practical applications and demand for embodied carbon measurement
Practically, embodied carbon assessments are meeting an increasing market demand driven by corporate ESG policies, certification requirements (such as LEED), government strategies and, in limited instances, legislation. There have been many publications on the issue, but awareness has only been raised relatively recently.
A significant paper entitled “Bringing Embodied Carbon Upfront” was published by the World Green Building Council in 2019, describing itself as a call to action.
Arguably the most accessible publication on embodied carbon to date, this paper has been referenced by multiple sources as governments develop and announce their net zero strategies one after another.
AECOM have utilised the advances in carbon data and database development by producing their own embodied carbon assessment tool, ScopeX™. The tool has been developed with the intention of helping architects and engineers understand the carbon impact of their projects, allowing clients to identify reductions in embodied emissions.
In the UK, where the RICS has undertaken most of their work to date in developing embodied carbon measurement methodologies, there has been pressure on the government to act to reduce embodied carbon through incentives and legislation. In particular, if they are to achieve a target of net-zero emissions by 2050. For instance, the ‘Part Z Group’ of architects, developers and contractors, including the Royal Institute of British Architects (RIBA) and the Institution of Structural Engineers (ISE), proposed that a new section (Part Z) is added to UK building regulations to compel projects over 1,000m2 to report embodied carbon emissions.
The ISE have followed this with their own guide for members, “How to Calculate Embodied Carbon”, in 2020 that highlights the need to calculate CO2e in all projects and provided a structural carbon rating system (SCORS) to allow structural engineers to classify projects on a scale of A to G. Perhaps, understandably in the context of market and political pressures from their exit of the European Union and the coronavirus pandemic, the UK government has been reluctant to consider implementation of further complications in a major sector within a struggling economy. However, as a recovery is now underway, they have begun to consider how to address embodied carbon within a wider heat and building strategy, a move supported by the sector by the UK Green Building Council.
There is far more that can be done though. The UK government itself is the subject of an environmental campaign over the construction of a new Justice Quarter in the City of London, which aims to combine police and judicial headquarters on Fleet Street. Campaigners say the plan, that currently involves demolition, could be amended to refurbish the existing buildings instead, saving approximately 19,000 tonnes of CO2e in the process. This highlights how refurbishment, rather than building new, can help to reduce carbon emissions. It also demonstrates how an understanding of embodied carbon could be used to reduce the carbon impact of a project, and how much influence governments could have to achieve the reduction.
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 acknowledges 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 take action.
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 acknowledges there is a way to go.
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’ 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 the lenders, who are under increasing scrutiny for lending to fossil fuel industries in particular. High profile examples of sustainability linked financing include the first such agreement between ING and Philips in Europe in 2017 and between Bank of America and General Mills in the United States in April 2021. While Europe is still at the forefront of this way of financing, the United States have seen a huge increase in demand in the last two years and lenders such as HSBC made Sustainability Linked Loans available for all their commercial clients in summer 2021.
In the Middle East, Aldar Properties announced in July 2021 that they have secured an AED 300 million Sustainability Linked Loan with HSBC linked to KPIs, becoming the first MENA company to do so.
Summary
Absolute values of embodied carbon measured are dependent on many factors that produce a level of uncertainty on a definitive value of CO2e, in keeping with internationally accepted methodologies for conducting lifecycle analysis. The key to their effectiveness is consistency in approach. So long as the methodology and reference points for embodied carbon measurement stay consistent, embodied carbon assessments can be an effective tool for the measurement and reduction of carbon within the built environment as comparisons between materials are being made on a level playing field. The need to maintain EPD databases and their growing datasets from increased numbers of EPDs undertaken over time will provide more robust data points and more accurate assessments. Tools developed and used to provide embodied carbon assessments need to understand the multiple variables – such as geographic location of a project – to provide meaningful, relevant results.
An understanding of the challenges helps to produce effective tools for measuring CO2e in projects and there are currently only a handful of companies and organisations that have the ability to do this. The effort and resources required to develop such capability mean that such abilities may be restricted to larger organizations in the short to medium term. Motivation to invest in the development of this capability may come from internal ESG policies, or external demand factors driven by legislation and market need to quantify CO2e within projects.
Conversations around reducing our carbon impact are usually focused on emissions resulting from direct user activity. We all need to drive less, 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 ‘up front’ during manufacturing and the construction phase alone and continue to be incurred throughout the asset’s lifecycle from maintenance, repair, replacement and demolition.
The need for the construction industry to understand, measure and reduce embodied carbon within projects 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.