Construction

Reducing carbon emissions in construction: Embodied carbon vs operational carbon

With the built environment contributing nearly 40% of our global greeenhouse gas emissions, reducing whole life carbon in buildings is critical to our net zero goal.

Words:
Charlotte Cameron
Images:
Shutterstock
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The global push for sustainability and the race towards net zero have propelled carbon-intensive industries like construction into the spotlight. 

As we grapple with the reality that the built environment contributes nearly 40% of our global greenhouse gas emissions, the need to reduce carbon emissions in construction becomes paramount. 

Globally, it’s estimated that we build the equivalent of a city the size of Paris each week. Yet surprisingly, less than one per cent of buildings are assessed to determine their carbon footprint. Because of this rate of growth, it’s vital that every building, house or development addresses embodied and operational carbon – two facets that make up the whole life carbon of a building to ensure it has a positive impact on society and the environment, with a clear purpose in meeting the needs of the communities it serves. 

Understanding these types of carbon will help reduce whole life carbon, maximise energy efficiency to reduce unnecessary costs and waste, and produce a place to enable healthy and happy living. Historically, the industry has been a slow adopter of new technologies and sustainability initiatives, but the emergence of sustainable buildings and practices is now transforming the sector.

In this blog post, we will delve into the differences between these two types of carbon and how they play a crucial role in the environmental footprint of buildings.

Embodied carbon vs operational carbon

Embodied carbon represents the carbon dioxide equivalent (CO₂e) associated with the non-operational phase of a construction project, including carbon emissions associated with extraction, manufacturing, transportation, deconstruction, disposal, and end-of-life of materials and processes. 

On the other hand, operational carbon refers to energy and water consumption during a building’s occupancy, encompassing emissions from regulated energy consumption such as electricity, heating, cooling, ventilation, lighting, and water use needed to operate the building.

Next, we will delve into a comprehensive exploration of both embodied carbon and operational carbon, unravelling their distinctive contributions to the whole life carbon footprint of a building.

Embodied Carbon: Building’s Carbon Footprint from Materials and Construction

Put simply, operational carbon encompasses the energy and water consumption directly attributable to the building’s occupants. On the other hand, embodied carbon encompasses all other factors, such as the construction of the building, the upkeep and repair of materials, and the end-of-life impact of those materials.

Embodied carbon, constituting over 30% of all global emissions in buildingsdemands attention. From the extraction of raw materials to the construction phase, every step plays a crucial role in determining a building’s embodied carbon. Developers and contractors must prioritise its reduction to meet net zero targets. In turn, developers could cut costs, mitigate resource risks, and navigate evolving regulations and planning permissions.  

Strategies for Embodied Carbon Reduction:

One effective strategy to reduce embodied carbon is the reuse of existing foundations and structures through renovation projects, potentially saving up to 75% of embodied carbon. 

Concrete, a vital building material due to its strength and adaptability, sees annual usage of 90 million tonnes in the UK alone. However, its production contributes significantly to carbon emissions, with the cement industry alone responsible for at least 8% of global emissions. Decarbonising the concrete sector is pivotal for reducing carbon in construction. Progress is underway with innovations like cement replacements such as Pulverised Fuel Ash (PFA) from coal-burning power stations and Ground Granulated Blast-furnace Slag (GGBS) from the iron and steel industry. While these by-products offer a positive transition, a more comprehensive solution, eliminating the processes of generating them, is essential for long-term sustainability.

In addition to this, incorporating low-carbon building materials, coupled with second-hand materials, can help further reduce a building’s embodied emissions. A notable example is steel, where brand-new steel carries an embodied carbon footprint five times greater than recycled content steel. This underscores the importance of choosing sustainable alternatives to contribute to a more sustainable construction industry. 

Operational Carbon: Building’s Carbon Footprint from Energy Consumption

Operational carbon, which refers to the energy and water use by building occupants, saw a promising 18% reduction, between 2018 and 2022, as reported by the UKGBC’s Net Zero Whole Life Carbon Roadmap Progress Report; attributed to advancements in decarbonising the electricity grid and enhancing energy efficiency. However, the overall UK built environment emissions fell short of the Roadmap’s targeted 19% reduction, registering a 13% decrease during the same period, highlighting the need for further improvements.

Strategies for Operational Carbon Reduction:

Implementing energy-efficient measures, such as utilising energy-efficient appliances, optimising insulation, and integrating renewable energy sources, can significantly reduce operational carbon. For example, installing solar panels on an office roof reduces operational carbon by generating clean, renewable energy from sunlight. Traditional energy sources, like fossil fuels, emit carbon dioxide during electricity production. By shifting to solar power, the office minimises reliance on such carbon-intensive sources, effectively cutting carbon emissions associated with its daily operations. This transition to a sustainable energy solution also contributes to a significant reduction in the office’s overall operational carbon footprint.

Building regulations and certifications often prioritise minimising operational carbon, recognising its direct impact on the day-to-day environmental performance of a structure but it is important to consider the whole life carbon footprint of every development.

Finding the Balance: Embodied vs. Operational Carbon

The UK construction industry must intensify its efforts to reduce embodied and operational carbon if we are to meet the country’s ambitious goal of achieving net-zero emissions by 2050 and align with the Paris Agreement’s objective of limiting global warming to 1.5°C.

Focusing solely on operational carbon neglects emissions from material extraction, manufacturing, and disposal. Similarly, an exclusive focus on embodied carbon may overlook ongoing emissions during product or building usage. Reducing both embodied and operational carbon, or in other words, the whole life carbon, provides a holistic perspective, informing decisions in sustainable design, construction, and operation. 

Whole Life Carbon and the Lifecycle Assessment

Whole life carbon, is defined as ‘the combined total of embodied and operational emissions over the whole life cycle of a building’. This holistic approach evaluates the entire life cycle, encompassing emissions from raw material extraction to the end of a product or building’s useful life.

Striving for lower whole life carbon ensures optimisation across all life cycle stages, contributing to a positive environmental impact and addressing climate change.

Developers can measure their whole life carbon with a Life Cycle Assessment (LCA). LCA allows a comprehensive understanding of a building’s environmental impact, from material procurement to decommissioning; emerging as the most effective approach for developers.

What is life cycle Assessment?

A life cycle assessment is a methodology for assessing the entire environmental impacts of a product, process or service throughout all stages of its life cycle. In construction, it involves calculating the whole life carbon of development.

Embodied_carbon_vs_operational_carbon

17 years of carbon reduction in building

One company making huge strides in their sustainability efforts, stretching way beyond compliance to set a new standard for best practice is Planet Mark member Prologis UK.  

Over their 17-year partnership with Planet Mark, Prologis UK has achieved a reduction in carbon emissions of 628,490 tC02e across 87 projects, an average reduction in whole life carbon emissions of 29% (as of January 15th 2023). They’ve done this by embedding sustainability into the design process, operations, community impact, and supply chain to ensure end-to-end visibility of carbon emissions and opportunities for reductions.  You can find out more about their incredible journey and our partnership here.

Planet Mark’s Built Environment Programme

Alongside Business Certification, Planet Mark also offers a Built Environment Programme hosting a suite of products and services, with 35 developments through this certification so far. Planet Mark’s certified members average whole life carbon reduction per development is over 29%. 

With significant carbon reduction and wider sustainability opportunities during the design stage of a development, our Design Stage Analysis promotes meaningful early engagement and facilitates the exploration of low-carbon design solutions.  

Within the construction phase, our Development Certification measures actual whole life carbon emissions through an LCA, providing a clear, digestible breakdown, including both embodied and operational carbon emissions. This is delivered through three simple steps – measure, engage and communicate. As part of the engagement stage, projects going through the Development Certification have the opportunity to support local primary schools with curriculum-linked workshops and assemblies, provided by the Eden Project, to engage both pupils and staff.  To have a positive effect on our communities, the certification enables local schools to achieve School Certification to help them calculate their annual carbon footprint and save money.

Similarly to the Development Certification, our Fit Out and Retrofit Certifications requires the measurement and reduction of whole life carbon emissions, while the Property Certification, once a building is complete, supports tenants in making annual operational carbon reductions.

Learn more about our Built Environment programme today.
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