What is the Difference Between Operational and Embodied Carbon?

Updated: Apr 21

We know carbon emissions are bad.

We know we need to limit them or stop them completely if possible.

But what is the difference between operational and embodied carbon? Is one easier to reduce than the other?

Operational carbon

This one is easy to remember.

Operational carbon is the type of carbon produced when operating the building.

It includes,

  • Lighting,

  • Heating,

  • Ventilation,

  • Cooling, or air conditioning, and

  • General power usage throughout the building.

Buildings are currently responsible for 39% of global energy related carbon emissions: 28% from operational emissions, from energy needed to heat, cool and power them, and the remaining 11% from materials and construction.[1]

To enable building managers to achieve net-zero by 2050, as outlined in the Government’s Net Zero Strategy: Build Back Greener, how buildings use energy will need to be considered. There is a rising call for this to be considered from the very beginning of a building’s lifecycle, in the design stage.

You could be forgiven for assuming that this is the time to consider embodied carbon, but by considering building use in the earliest design stages, changes can be made before construction begins, reducing carbon emissions, construction waste, time, and money.

"At this stage, alternative layouts and materials can be considered and details can be refined to use less material. As the design progresses these opportunities diminish."[2]

Infographic for different types of carbon found in buildings

[3]Some tweaks to design can be simple, for example on a building with lots of windows, cooling costs are likely to be high in the summer, as an increased number of windows can increase internal temperatures, described as solar thermal gain. By repositioning windows, designs can counter-act the warming potential of sunshine and reduce future cooling costs from air conditioning before they are needed. Alongside solar thermal gain, architects can also consider the impact of light distribution from window placement. Implementing open-plan spaces, light interior finishes, integrated sunshades, and light shelves[4] can increase daylight penetration, while stopping increased heat from entering the building, cutting CO2 emissions for lighting requirements.

By considering all options at the design stage, architects and asset owners can ensure that the most efficient system is fitted and can plan the space around its essential components, rather than planning the space, and having to fit in the components at a later stage.[5]

This provides the most energy-efficient systems with the best chance of success, alongside reducing construction waste and time as plans will remain unaltered.

Photograph of a large, open window

Embodied carbon

Embodied carbon is the one that is often confusing.

Embodied carbon is all the CO2 emitted in the production of the building. This includes,

  • the extraction and production of materials used during construction,

  • the transportation of these goods from manufacturing sites to the construction site.

  • Plus, the carbon released by plant and machinery throughout the building process itself, and

  • in the case of rebuilds, demolition and retrofitting.

It is occasionally termed ‘upfront carbon,’ as they are the emissions that are generated before the building is used, but for simplicity, we will go with the majority and refer to it as embodied carbon.

The toll of embodied carbon in the construction industry is potentially huge, and it is only set to increase. While it currently accounts for 11% of greenhouse gas emissions, with the projected increase of construction initiatives over the coming decades, it’s believed that by 2050 embodied and operational carbon emissions will be the same.[6] So it is essential that the construction industry addresses the implications of an increased built environment.[7]

Concrete being poured and levelled.

Some ways to lessen the impact of embodied carbon include:

  • Retrofitting, and reusing buildings, usually saves 50-75% of embodied carbon emissions, especially if the foundations and structure are maintained.

  • Use low-carbon concrete mixes- as concrete alone remains responsible for 4-8% of the world’s total CO2 emissions.[8]

  • Use less carbon-intensive materials- swapping aluminium, plastic, foam, steel, and concrete for wood, straw, and hemp.

  • Reuse materials, as second-hand, recycled, or salvaged materials have a much lower carbon footprint, especially steel, which has an embodied carbon footprint 5x larger than recycled content steel.

  • Use fewer finishings, instead polish or leave bare structural materials.[9]

To achieve the ambitious net-zero target by 2050, embodied and operational carbon will need to decrease drastically. The fastest way to achieve this is by factoring in both embodied and operational carbon emissions factors when designing, building, managing, and later reusing the building in question.

Only then can building practices be considered sustainable.

____________________________________________________________________________ [1] Quote from World Green Building Council, WGBC, ‘Bringing Embodied Carbon upfront,’ <https://www.worldgbc.org/embodied-carbon> [2] Quote from Andrea Charlson, from Metal Architecture, ‘8 tips to reduce your Buildings Carbon footprint,’ published 30.09.2014, <https://www.metalarchitecture.com/articles/8-tips-to-reduce-your-building-carbon-footprint> [3] Image from Carbon Cure, ‘What is embodied carbon?’ published 22.09.2020, <https://www.carboncure.com/concrete-corner/what-is-embodied-carbon/> [4] Quote from Steve Fronek, PE, LEED Green Associate, vice president of technical services at Wausau Window and Wall Systems in Wausau, from Metal Architecture, ‘8 tips to reduce your Buildings Carbon footprint,’ published 30.09.2014, <https://www.metalarchitecture.com/articles/8-tips-to-reduce-your-building-carbon-footprint> [5] Image from Pexels.com, courtesy of Olya Kobruseva [6] RPS Group, ‘Embodied carbon: What it is and how to tackle it,’ <https://www.rpsgroup.com/services/environment/sustainability-and-climate-resilience/expertise/what-is-embodied-carbon/> 14.03.2022 [7] Image from Pexels.com, courtesy of Rodolfo Quirós. [8] Data from the Chatham House Report, ‘Making concrete change: Innovation in Low-Carbon cement and concrete,’ by Johanna Lehne and Felix Preston, published 13/06/2018, <https://www.chathamhouse.org/sites/default/files/publications/2018-06-13-making-concrete-change-cement-lehne-preston-final.pdf> [9] RPS Group, ‘Embodied carbon: What it is and how to tackle it,’ <https://www.rpsgroup.com/services/environment/sustainability-and-climate-resilience/expertise/what-is-embodied-carbon/> 14.03.2022

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