By Tercia Jansen van Vuuren

The construction sector has a fundamental role in providing the infrastructure needed for society to thrive and ensuring that development responds to the challenge of climate change by reducing carbon emissions, ensuring resilience, and adapting to changing conditions. The built environment is directly responsible for a quarter of the UK’s greenhouse gas emissions and is therefore critical in driving change to achieve the UK’s net-zero target by 2050. Emissions arise from the processes and materials used to construct our towns, cities and infrastructure as well as in the energy needed to heat and power buildings and operate infrastructure.[1]

Over the last few years, there has been a significant increase in consideration of climate change and carbon emissions across the construction sector, with pressure to act coming from multiple angles, including public demand, government requirements, and client aspirations. This has led to a surge in industry action, including initiatives, working groups, reports, tools and calculators, commitment schemes and so forth. All this activity can be overwhelming and it can be difficult to know where to begin when seeking to understand what changes we need to be making or where to look for guidance. The Laing O’Rourke Centre for Construction Engineering and Technology at the University of Cambridge has developed a ‘Decarbonising Construction Landscape Map’ that provides a visual representation of many of the groups, institutions and initiatives that are active in transitioning the construction industry to net zero. This follows from an investigation into the breadth of current research into decarbonising the built environment at the University of Cambridge, which has been presented in an interactive, visual map.

Before presenting the Decarbonising Construction Landscape Map, it is helpful to take a step back and look at what it means to decarbonise construction. We need a framework for understanding the many ways in which the climate change challenge is being addressed in the built environment and how these different themes and activities fit together.

The first aspect to understand is that 'construction' includes both buildings (domestic and non-domestic) and infrastructure and all types of projects from new-build to refurbishment or retrofit and assessment of existing assets. ‘Construction’ therefore encompasses the full gamut of the built environment. All activities and people involved in executing these projects can be levers in stimulating change in the industry. 

© Tercia Jansen van Vuuren, Laing O’Rourke Centre. University of Cambridge.

The second important attribute is that ‘construction’ is not limited to the on-site construction phase of the project. It starts at the very beginning at the strategic planning phase and extends all the way through operation and maintenance of assets until end-of-life. This is illustrated in Figure 1. The carbon reduction curve[2] highlights that the opportunities to influence carbon on a project are greatest at the start, when the option to ‘build nothing’ or ‘build less’ are still available, and dramatically reduce as the project progresses.

Considering the broad range of activities and projects included in the construction sector, we can now look at the topics and themes within decarbonising construction. This gives us the ability to see how the different parts fit together in creating a net-zero carbon world. The mind map in Figure 2 provides a visualization of the themes and topics that comprise the overall challenge of ‘decarbonising construction’. There are many links and overlaps in the work that is happening both in industry and in academia, with some work addressing multiple themes and some very narrowly focused on specific aspects of a theme. A brief description of the main categories illustrated on the mind map is given below.

• Embodied carbon: There is considerable work around how to reduce the embodied carbon of construction from a materials perspective, such as increased use of natural materials, especially timber, and how to promote low carbon concrete. Work in this area also includes general guidance around what embodied carbon means, measurement methodologies, and tools and calculators.
• Operational carbon: Given the large proportion of GHG emissions associated with heating and powering buildings, a significant area of work is around minimising the energy requirements of buildings. This includes performance modelling and monitoring, retrofit of existing buildings to meet zero carbon requirements, and low carbon heating.
• Whole life carbon:  Whole life carbon recognises that embodied and operational should be considered together as they are dependent on each other, for example the choice of construction materials influences the thermal mass, which impacts the operational energy requirements.
• Material efficiency: The work around material efficiency looks at how utilization of materials can be maximized so that we use as little as necessary and includes reduction of waste in both design and construction. Being resource efficient will reduce the embodied carbon, therefore, these themes are linked, but it is a separate avenue of focus.
• Circular economy: This theme is linked to both ‘material efficiency’ and ‘embodied carbon’. The purpose is to maximize the value obtained from existing materials and assets thereby reducing the need for new materials and reducing embodied carbon impacts. Work includes investigation into reuse of materials and the processes to enable this (such as deconstruction, verification, and resale) and adaption and reuse of existing assets.
• Construction processes: Work in this field addresses the processes used during the construction phase, such as electrification of on-site construction vehicles, increased use of off-site manufacturing, and automation of construction.

• Procurement: A fundamental aspect of reaching net zero by 2050 is understanding how clients and the construction industry engage with the supply chain to procure and deliver projects that achieve their carbon reduction ambitions.
• Organisation impacts: This relates to the organisation’s own emissions from owning and operating assets (scope 1 and scope 2 emissions), as well as the emissions that they have influence over through purchasing or the work they undertake (scope 3). There are many commitment schemes and processes to assess these corporate emissions.
• Offsets: Although carbon offsets are not directly related to the construction industry, it is helpful to understand how they fit into the picture. Since carbon is sequestered in timber, a key aspect of this work is around how to account for sequestration in timber that is used in construction.
• Systems level issues: Outside of construction, various aspects are particularly relevant for investigating how to stimulate change in the industry, as well as understanding how the construction industry interacts within the broader context of society (e.g. user carbon, urban planning).

Now that the framework has been established for understanding how the construction industry is addressing the challenge of mitigating climate change, we can come back to the ‘Decarbonising Construction Landscape Map’ and look at the many initiatives, research programmes, and working groups that are active in this area. The purpose of this map is to provide an overview of activities and direct users to organisations or information that may be useful in their own understanding of decarbonising construction. Given the pace of development in this area, the map is not meant to be a fully comprehensive guide but a signpost to relevant action and information. It is also a living resource and will need to be continuously updated to stay current.

The primary focus of the map is on carbon reduction and climate change mitigation in construction and does not include other aspects of sustainability in the built environment, such as nature-based solutions, biodiversity, health and well-being, community, and climate change adaptation. There are many additional resources and initiatives that delve deeper into these related aspects of sustainability.

Access the full Landscape Map here.

In summary, the broad spectrum of stakeholders and range of types of projects and activities that comprise the industry, together with the long history of reliance on traditional methods with carbon-intense materials such as concrete and steel, makes construction a particularly complex sector to decarbonise. However, the construction industry is rising to the challenge of changing the way we do things to move towards net zero carbon by 2050. Through upskilling the sector and building on the collective action already underway, we can use our influence to address our own areas of impact within the landscape of decarbonising construction.

To understand how to navigate the ‘Decarbonising Construction Landscape Map’ and find relevant information, please see the User Guide that has been produced. For any comments or queries regarding the landscape map, please contact comms@construction.cam.ac.uk at the Laing O’Rourke Centre, University of Cambridge.