More and more companies and industries are claiming that their products are “carbon neutral”, “zero carbon” or even “carbon negative”. But upon closer inspection this claim doesn’t appear true. Electric cars don’t emit greenhouse gases while they move, but their production does involve carbon emissions. So the correct way to perceive and calculate their impact is not only to look at the lifespan of the cars after they are produced, but also their entire lifecycle – sourcing of raw materials, production, usage by the consumer and finally their repurposing or decay.
With this in mind we decided to delve deeper into what embodied (sometimes referred to as “embedded”) carbon is, how it differes from operational carbon, how it gets assessed and how it can be reduced.
What Is Embodied Carbon?
The scale of increasing carbon dioxide emissions in the atmosphere is focusing the attention of industry and businesses towards measuring and mitigating those emissions. The term embodied carbon or also called embedded carbon, refers to the collective of GHGs that participate in the whole production process of a product up to the point of usage.
That includes the emissions generated in the mining of the materials, the transportation, refining and manufacturing, the production process itself, and end-of-life disposal or recycling. In other words, calculating the GHGs starts from the cradle which is the earth and continues till the end of life.
Another definition for embodied carbon is that it covers greenhouse gases that are incurred from the energy and industrial processes used in the processing, manufacture and delivery of the materials and components required to construct the end product .
When we take buildings as an example, the embodied carbon included in them comprises: the emissions released during mining of materials, transportation of those materials, materials refining, packaging and distribution to the construction site, assembling activities and waste disposal from construction. Eventually, at the end of the life of the building, emissions related to demolition, removing, disposing and recycling are also included.
Embodied carbon in products is normally not known to the final consumer. According to studies, they comprise between 20% and 50% of total carbon footprint. That is a significant number and it shows what a big percentage of emissions comes from the creation and manufacturing of materials that are used to make the final products.
If embedded emissions are omitted when calculating total emissions, that would risk neglecting a large amount of upfront carbon emissions and thus give a false indication of where reductions should be implemented.
Embodied Carbon Vs Operational Carbon
Embodied carbon differs from operational carbon which comprises the emissions released only during operation of the product. For example, operational carbon in buildings comes from energy, heat, lighting, etc, or everything that is needed during usage.
The exception is emissions related to maintenance of the building like refurbishing, replacement, deconstruction, that are also accounted for in the embedded carbon emissions.
Unlike operational emissions, the embodied GHGs cannot be reversed, meaning once released there is no more opportunity for improvement. Operational emissions, on the other hand, can be improved at any point, for example by installing energy efficient measures in buildings.
The embedded carbon and the in-use carbon emissions from the operation together make up the complete lifecycle carbon footprint of a product. A life cycle assessment is usually conducted to measure the entire carbon footprint.
Why Does It Matter?
The world needs to meet the targets of reaching carbon neutrality by 2050 to curb emissions up to 2C degrees. By 2060, studies show that the world population is expected to increase by about 2.67 billion people. With the rising global population, that means the need for reducing global emissions would be even bigger.
Embodied carbon emissions are estimated to take between 20% and 50% of total emissions for products. For new buildings, they are expected to account for around 50% of the overall carbon footprint from now until 2050.
Due to rising population and urban development, the world’s building stock is expected to double by 2060. That is an equivalent to adding an entire New York City to the planet every month for the next 40 years.
Therefore, it is critical for the world to find ways to cut embodied emissions as they will continue to rise under business-as-usual scenario. For the built environment sector alone, a reduction of a total of 84 gigatons of CO2 by 2050 is needed to adhere to the limiting global temperature increase to 2°C goal.
In the current economies, the risks of rising or volatile energy and materials costs are a significant threat to the profitability. Reducing embodied carbon of projects helps mitigate those risks by ensuring that materials are used optimally and that the manufacturing, transportation and construction processes are energy efficient.
Managing embodied carbon not only cuts costs but it also marks carbon savings. That translates directly into an increase in environmental and public health which indirectly brings a snowball effect of other benefits to the society.
Embodied Carbon Assessment
Assessing the embodied carbon of a product is a fairly new field of research and lacks universal quantifying standards. However, there is a considerable amount of work that is constantly being done in order to standardize methodologies for the CO2 measurement.
Since embodied carbon is a subset of the Life Cycle Assessment (Analysis) (LCA), it adheres to many of the same standards. The Life Cycle Assessment is the most widely used and accepted tool for quantifying the environmental impacts of products and services, first developed in the 1960s.
It involves the collection and evaluation of quantitative data on the inputs and outputs of material, energy and waste flows associated with a product over its entire life cycle so that its whole life environmental impacts can be determined.
There are other methodologies and protocols that were developed recently on carbon dioxide measurement, some of which relate to a company footprint, others to installations and others to a product.
- The Greenhouse Gas Protocol – it sets a comprehensive global standardized framework to measure and manage GHG emissions for companies and organizations, value chains and mitigation actions
- PAS 2050 – assessing the life cycle emissions of goods and services
- ISO 14064-1 – it outlines requirements at the organization level for quantification and reporting of greenhouse gas emissions and removals
- The ISO 14064-2 – it specifies principles and requirements at project level for quantification, monitoring and reporting of activities that cause GHG reductions or removal enhancements
- ISO 14064-3 – a guidance for those conducting or managing the validation and/or verification of greenhouse gases.
Buildings account for carbon emissions. Embodied carbon of construction products can be assessed using the following benchmarks and standards:
- LETI Climate emergency design guide
- WGBC Bringing embodied carbon upfront
- UKGBC: Net zero carbon buildings: A framework definition
- RIBA 2030 Climate challenge
- Whole Life-Cycle Carbon Assessments guidance published by the Major of London
- IStructE How to calculate embodied carbon
- RICS Whole life carbon assessment for the built environment
Step Undertaking The Assessments
As the carbon assessment standards are voluntary, boundaries of what part of the product life cycle should be included in the embodied carbon measurement need to be determined.
Assessments that are undertaken only to the point where the product leaves the factory gate are called cradle-to-gate. When the assessment of embodied carbon comprises all stages of its life cycle including demolishing, materials disposal, recycling or reuse, it is called cradle-to-cradle.
Usually, it is better to include more stages of the lifecycle in the embodied carbon assessment, as more of the carbon emissions associated with the product or building will be brought into the analysis.
The undertaking of the embedded carbon measurement include the following steps:
- Defining system boundaries, i.e. what is included from the life cycle assessment
- Using a recognised methodology for the collection of the embodied carbon assessment data for the materials and products
- Making sure the data for the chosen assessment is consistent like the functional units of the product or system and the timescale for the life of the product is determined
- A proper allocation of the carbon load of materials/products involved in the assessment when, for example, several products or functions share the same process
- Sharing the assessment to improve the size and robustness of the industry dataset
The embedded carbon in different materials that participate in the construction of the end product is usually calculated by finding the quantity of the material and multiplying it by the carbon factor. The carbon factor is expressed in a kilogram of CO2 equivalent per kg of material.
Sometimes complications can appear as there is no one single source of accurate and exhaustive data for the emissions of materials and products. Not all carbon factors for the materials consider the carbon associated with the different boundaries of the life cycle. Some carbon factor calculations consider the carbon from cradle to gate, others from cradle to cradle.
Most of the data on construction products for example covers mainly cradle to gate stages and data on the impacts covering more life cycle stages is under development and being updated by the industry.
Publishing the embodied carbon assessments is also critical for the robustness of the datasets. The more the industry shares its embodied calculations, the more improvements will continue in the accuracy of calculations and benchmarks.
Ways To Reduce Embodied Carbon
The ultimate goal of calculating carbon footprint and thus embedded carbon is to reduce the environmental impact GHGs have on the planet. Their harmful global warming potential is changing the balance in the environment and substantially affects people’s lives.
The obtained embedded carbon figures from the life cycle assessment are critical to inform decision-making on where cuts in emissions could be implemented. The data can also reveal which elements of the production process hold the most significant proportion of the overall embodied carbon.
An area that is responsible for an intense concentration of greenhouse gas emissions is also known as a carbon hotspot. An example for carbon hotspots could be the foundations and ground floor of a home as they were found to dominate the carbon impact. Identified carbon hotspots have the potential to provide significant opportunities for carbon emissions reductions.
There are a number of carbon reduction measures that could be taken to minimize the impact of embedded carbon. Some of them include using products that are made from locally available raw materials, transporting materials with electric or hydrogen-powered vehicles, minimizing materials use or using products with high recycled content.
Using materials that are sourced nearby reduces significantly the CO2 emissions of buildings for example, as it cuts the transportation emissions and it is more energy-efficient. Another way to optimize embedded carbon is to use systems and products that have long life spans or designing the building in a way to minimize future refurbishments.
Some additions that can improve the efficiency of a building like adding insulation or replacing old systems with more energy-efficient ones can avoid embodied carbon. Choosing a lower carbon alternative for a material is often used in construction to save emissions.
For example, a wood structure instead of steel and concrete one, or wood siding instead of vinyl, can reduce the embodied carbon in a project. Cement replacement materials like GGBS ground granulated blast furnace slag or pulverised fuel ash are preferred for some projects. Materials like metals, plastics and aluminium are very carbon intensive products so engineers often look for lower carbon alternatives.
Saving and reusing products is normally less carbon intensive than buying new ones, as the carbon associated with making them is already spent. Therefore, salvaging materials and products is an effective method to minimize embodied carbon.
Recent initiatives taken by societies and governments towards reducing man-made CO2 emissions are putting bigger importance on embedded carbon. The increased spotlight on embodied carbon as part of the life cycle assessment of a product or building is important in better identifying ways to reduce carbon footprint.
Nowadays, there are some sources that facilitate and set a framework for the assessment of embodied carbon, although further work needs to be done to produce a unified standard. Methodologies have begun to emerge recently on how to measure embedded carbon in a standardized way which is a big step forward towards achieving better emissions reductions across industries.