Why is the picture so confusing? Is embodied carbon or whole life carbon the correct way to assess construction projects? And what does all of this mean if you are just starting to think about reducing the carbon your projects are responsible for
What is embodied carbon?
Every building we construct, retrofit, or demolish and rebuild has a carbon cost. Raw material extraction, product manufacturing, transport to factories and construction sites, as well as assembly and construction, all results in the emission of greenhouse gases before a building is even occupied.
While a building is in use, components must be maintained, repaired or replaced. These processes also emit greenhouse gases.
Once a building has served its purpose, it is often demolished. The act of demolition or deconstruction, and the processing of waste materials, is all part of the ‘life cycle’ – and contributes to emissions yet further.
You can view the life cycle at the level of individual products or components, or the level of the whole building (or ‘asset’). Whichever the case, the total emissions associated with all these stages/processes is the embodied carbon of the product/component or building/asset.
Find out more about how life cycles are assessed in modules in our blog post about embodied carbon and life cycle assessment.
What is whole life carbon?
If embodied carbon accounts for emissions throughout a product or building’s life cycle, how can there be a different measure called ‘whole life’ carbon?
The difference is the operational carbon; the emissions associated with energy and water use to heat and power the building. Whole life carbon can therefore be defined as follows.
Embodied carbon + operational carbon = whole life carbon
The reporting of embodied carbon can be subject to different definitions, which only serves to add to the confusion within the construction industry. This definition of whole life carbon is unambiguous, as it includes everything associated with a building’s life. At Darren Evans, we prefer to carry out whole life carbon assessments rather than embodied carbon assessments.
Choosing to tackle embodied or whole life carbon
Uncomfortable as it may be for the construction industry to admit, the only building that has zero environmental impact is the one that does not get built. Sustainable construction isn’t about emissions alone. Underpinning it is issues of efficiency, of responsible sourcing and responsible specification.
Construction consumes natural resources and raw materials that are finite. Their extraction impacts the communities local to where they are sourced. Biodiversity loss is exacerbated by exploring new regions for raw materials, and by the growth of urban areas as the number of new buildings increases. When we talk about the life cycle impacts of products and whole buildings, these wider issues should not be forgotten.
Tackling embodied carbon and whole life carbon starts with questions. Is a building needed? If so, does it need to be constructed from raw materials? Can the need be met by adapting an asset that already exists (and for which the carbon cost has therefore already been counted)?
As decarbonisation of the energy grid continues, and the operational emissions of our building stock become net zero (see our net zero carbon white paper for more detail about this), the only carbon left to address will be the carbon embodied in the fabric of our buildings. We need to reduce it.
If we don’t, then the buildings constructed today will, in a century’s time, be subject to the same debates as the Marks & Spencer building – long after the target date of 2050 for net zero emissions.
The definition of whole life carbon is straightforward. The important thing is that whole life carbon includes everything in the life cycle. With that in mind, it’s possible to start taking action.
About the author
Darren Evans - Business leader connecting with people to treat people and planet as the precious resources they are so that we can build a better future together https://darren-evans.co.uk/