Why embodied carbon is key to achieving net zero

Reducing embodied carbon emissions needs to be addressed across a building’s lifecycle.

Embodied carbon emissions are not a footnote to the net zero carbon story. To have a legitimate net zero carbon strategy, companies need to include their embodied carbon emissions.

These are the emissions created in producing a building and maintaining it throughout its lifecycle. They make up around 11% of a building’s total emissions across a 60-year life and include:

  • Emissions generated when the raw materials needed to create a building (such as sand for concrete) are extracted, transported and manufactured
  • Emissions created during the construction process of a building or during installation of new equipment
  • Emissions created in the manufacture of equipment and materials needed when buildings are maintained, repaired, replaced or refurbished
  • Emissions generated at the end of a building’s life when it’s deconstructed or demolished

How embodied carbon emissions are measured and reduced is essential to reaching net zero carbon. While it’s one of the more complicated parts of a company’s journey, there are many opportunities to do so – depending on what stage the building is at in its lifecycle.

Reducing embodied carbon before the building is used

While emissions are embedded throughout the lifecycle of a building, the majority of embodied carbon is released before the building is even operational, i.e. in the sourcing, transport and assembly of the building materials. This is where there are most of the opportunities to reduce the emissions embedded in the building’s journey.

It’s crucial to consider your ambitions and targets for reducing embodied carbon in the very early stages of building design. These targets can inform building form and design approaches, as well as material choices, driving designs towards those which use less materials in the first place and which use materials with lower embodied carbon. Cross-laminated timber is often mentioned as an alternative to more carbon-intensive building materials, but there are many others, including recycled concrete and concrete where a proportion of the mix is made from crushed plastic.

For new developments and major renovations, emissions can be reduced by considering what existing or local materials at a site can be repurposed. If it’s a major renovation, can any of the load-bearing walls be retained so that carbon-intensive cement and steel do not need to be sourced anew? In either case, can the building be designed for disassembly so that the component parts can be recycled or repurposed at the end of life?

Measuring embodied carbon

Ensuring that the sources of embodied carbon can be measured from early on in the design process is key. Attempting to do so retroactively can be very challenging with developers finding that they don’t have the right data from their suppliers or haven’t captured it in a usable way to allow embodied carbon emissions to be calculated.

Even with data capture systems and processes in place, it can still be challenging to accurately measure embodied carbon. In lieu of measurements, there are a series of benchmarks available to estimate embodied carbon emissions. For instance, the Royal Institute of British Architects (RIBA) have estimates that current embodied carbon levels for buildings are around 1,000 kgCO2/m2. With benchmarks largely consolidating around this level, the industry has now started to develop targets of embodied carbon intensity, mostly looking to halve embodied carbon from between 2030 to 2050.

Reducing embodied carbon while the building is being used and at the end of its life

While the greatest potential to reduce embodied carbon is in the early stages of the process, investors and owners can account for the embodied carbon in their existing assets. In these cases, using recognized benchmarks, such as those mentioned above, will be essential for estimating the quantity of embodied carbon in a portfolio and exploring options for using high-quality carbon offsets to compensate for these emissions.

Thinking across the whole lifecycle

Throughout the entire process, a central element of effectively managing embodied carbon emissions is about employing circular economy solutions as early as possible in the process.

This includes exploring options to use less and maximize reuse of building materials, minimizing waste in the construction and use processes, and procuring locally and sustainably where possible.

And critically, it’s about ensuring there’s a design process that considers how all its building blocks are used during its lifetime and at the end of it.

Making the most of these opportunities will allow real estate to address the challenges that come with reducing embodied carbon.

This article is part of our Net Zero: The Big Questions series which looks at some the complex questions around how buildings can achieve net zero carbon. Check out the rest of the series below:

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