How to consider embodied carbon in the construction process

Industry blind spot

Over the last few decades, the UK government has tended to prioritise the reduction of operational (or Scope 2) carbon emissions – most notably through Part L of 2022’s updated Building Regulations for England, which set standards for the energy efficiency of new and existing buildings through Energy Performance Certificates (EPCs). This has resulted in a 30% reduction in emissions, over the last two decades, according to UKGBC Net Zero Whole Life Carbon Roadmap, 2021.

Although the considerable progress made in this area mustn’t be dismissed, this focus has often led to embodied carbon being overlooked – which is a far more significant contributor to emissions in the built environment. As it’s come increasingly under the microscope, some rather startling statistics have emerged in recent years. In 2021, UKGBC reported that annual embodied carbon emissions in the UK originating from the construction, maintenance and demolition of buildings amounted to 40-50 million tonnes of CO2 – that’s more than the combined emissions from aviation and shipping. In 2023, Carbon Blind Spots, consultancy Akerlof published analysis that highlighted ‘the urgent need for a heightened focus on Scope 3 emissions, supported by standardisation in emissions reporting.’ Indeed, it found that Scope 3 emissions account for an overwhelming 94 – 98% of organisations’ emissions (from an evaluation of 30 UK Tier 1 contractors).

Despite this, the reporting of embodied carbon isn’t yet mandated by the government. Leading industry figures have called for the addition of Part Z to the regulations, which would enshrine the practice in legislation. But the practice of reporting embodied carbon is gaining traction across the sector. A survey – released in April 2024 by the construction consultancy firm RLB – found that 33% of contractors are being asked by clients to provide whole life carbon assessments (WLCAs) on schemes, a substantial increase from last year’s 14%. In addition to this, Westminster City Council is the latest local authority to ask for WLCAs for all major redevelopment schemes. These signs of evolution within the built environment indicate the industry needs to get better at assessing, evaluating and comparing the carbon impact of both retrofit designs and materials in new builds.

How and what to measure

Over the years, it’s fair to say that the topic of embodied carbon has been shrouded in mystique. This, coupled with the lack of a mandate, may underlie the hesitancy to report it. As we’ve always reiterated it’s not possible to report something until you can be sure what exactly it is you’re measuring and how to measure it.

Therefore, it’s worth revisiting what embodied carbon actually is. Embodied carbon is all the energy used to create a product during the construction process, i.e. the sourcing and manufacturing of raw materials. This is also often referred to as ‘cradle to gate’ or ‘cradle to site’. In the modular system of a whole life carbon assessment it is known as A1-A3 – the product stage. It also covers A4-A5, the construction stage (see Figure 1).

Embodied carbon also includes the carbon emitted throughout its ‘use stage’ (B1-B7) – the maintenance, repair or refurbishment required to keep it functioning. In addition to this, it includes the energy released during a building’s ‘end of life’ stage (C1-C4). In whole life carbon assessments, it’s often referred to as cradle to grave. However, it can also include one final stage – the potential reuse, recovery, and recycling potential of the assets (D).

Historically, measuring whole life carbon in assessments hasn’t been easy, due to inconsistent application of the methodology on how to measure carbon, as well as a lack of available, consistent data.

Since the first edition of the RICS Whole Life Carbon Standard was authored in 2017, the industry has made substantial progress in overcoming many of the challenges involved in measuring, reporting and benchmarking carbon, which thwarted earlier attempts to tackle the issue of embodied carbon.

Making carbon add up

We now have the Built Environment Carbon Database – a pan-industry initiative – that continues to grow in asset data, enabling the industry to benchmark and report carbon emissions. We also have RICS’ second edition of whole life carbon assessment, effective from July 2024, which provides the methodology to assess embodied and operational carbon measurement in the built environment.

Crucially, this means it’s easier to put carbon cost/benefit analyses into practice. For example, it’s easier to compare the embodied carbon impact of installing more insulation in comparison to the corresponding carbon benefit in reduced energy use. These types of calculations can help to make a project more efficient and streamlined, saving time and money in the long term. It also means the industry can get better at assessing, evaluating and comparing the carbon impact of both retrofit designs and materials in new builds – this is likely to increase in importance as more councils and contractors require them.

What’s the purpose of a WLCA?

As the 2nd edition of the standard has come into effect (from 1st July 2024) RICS members are expected to follow all requirements specified for the relevant project phase and type. But as many within the industry attest, we’re still in ‘new terrain’ in terms of applying the standard – it will take time and practice to do correctly. The purpose is to measure the complete carbon footprint of a built asset or component throughout its life cycle. If conducted correctly, the WLCA will follow a structured method with a clearly defined scope that evaluates all the various stages from cradle to grave – i.e. the extraction and manufacturing of the asset or component to its operation, maintenance, and end-of-life.

The guidance recommends that all WLCAs follow a modular structure for carbon reporting, which breaks down the built asset’s life cycle into stages and modules (see Figure 1). It’s also been adapted from the European Standard EN 15978 that assesses the sustainability of construction works.

Combining a cost and carbon life-cycle plan

Whatever we build today should last many years. The choices we make in the design phase of construction have a direct impact on the costs related to the building and the amount of maintenance it will need.

These choices also influence the amount of environmental emissions throughout its life cycle. Our ability to reduce emissions diminishes as the project progresses. Therefore, it’s important to make the right decisions as early as possible.

And as we have previously proposed, it’s time to make the most of the cost experts we already have in the business. Quantity surveyors are best-placed to measure and benchmark carbon, as the underlying principles of cost estimating are very similar.

Back to business

The need to reduce emissions on a global scale is of course a huge motivator for many organisations and contractors. But there’s also a business case for lowering embodied carbon emissions. Taking action on embodied carbon can help give developers the competitive edge in the market but it can also save money. These methods include adapting the design to use less materials, re-using or recycling materials and using less carbon-intensive manufacturing. This can all help to reduce costs. Some designers are achieving this through implementing plans to recover materials through deconstruction and disassembly.

If we make progress in decarbonising the grid, it could lead to a reduction in the carbon numbers of some of the most common materials in construction, such as steel and cement, i.e. they could become less carbon-intensive. These methods will also help to diminish the risk of stranded assets that lose value because they don’t fulfil green credentials, as well as improve the chances of achieving required standards in green audits.

The global picture

According to the Global Status Report for Buildings and Construction, a third of all building-related emissions stem from embodied carbon. This accounts for around 10% of all energy-related GHG emissions world-wide. In the EU, about 60-70% of embodied emissions stem from the materials used for the initial building construction, also called upfront embodied emissions. These emissions are those derived from the life-cycle stages A1 to A5, defined in the European Standards EN 15978 and EN 15804, which cover the product and construction process stages over a building’s lifetime.

In addition to this, the global construction market is predicted to grow 42% by 2030. According to Architecture 2030, ‘the world is expected to add about 2.6 trillion ft² of new floor area to the global building stock between 2020 and 2060.’ (To put into context, that’s an entire New York City built every month for 40 years.)

Needless to say, with such staggering figures, it’s crucial for all countries to have a globally consistent method for whole life carbon reporting, as well as a methodology for all building and infrastructure construction projects. Therefore, the RICS standard is also aligned with the International Cost Management Standard 3 (ICMS3).

Conclusion

Historically, the industry has decades of data to inform its decisions concerning cost, but we lack a rich history of carbon data. Many carbon calculators on the market will purport to measure carbon emissions effectively, but the majority don’t measure and report all the stages needed in a whole life carbon assessment.

But the good news is that this data is constantly growing. The development of BECD has provided the foundations for designing an efficient way to measure and report carbon, by linking it to measurement processes that already exist on construction projects – such as cost estimating, cost reporting and cost control. Specifically, it’s laid the groundwork for the BCIS Life Cycle Evaluator, which holds reliable and auditable cost and carbon data for common building components, activities and construction materials. It also includes up-to-date costs and verified EPDs and LCAs; and this is continuing to grow and improve in quality.

Therefore, it’s now possible for everyone in the industry (whether an architect, engineer or designer) to be armed with the same pieces of information to make a difference and have an impact – whether that’s through upfront investment in energy efficient technologies, or choosing more sustainable materials that could lead to lower operational expenditure and increased life cycle longevity. This development could potentially produce game changing results for our industry, in terms of lowering carbon emissions and mitigating their impact in the construction industry. It could also help to support the industry and UK government in achieving its wider sustainable goals and net zero targets.

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