Enabling a low carbon materials economy

How can policy, industry and education foster a low carbon materials future? Professor Robert Hairstans, Founding Director of the Centre for Advanced Timber Technology, explores how construction materials, practices and design will have to change to realise a low carbon materials economy, while meeting future needs for the built environment.

How can we overcome barriers to the wider use of low carbon materials in construction and avoid being stuck in a high carbon pathway? This is an important question given the impact of construction and the built environment on climate change. Without rapid change to the materials, design and practices used, the global construction sector faces a risk of ‘locking in’ a high carbon pathway, as the sector grows to meet global demand for urban environments.

Meeting the global demand for developed urban environments

According to the UN, global population could peak at nearly 11 billion in 2100. To accommodate more people in better developed built environments, the total built space in the world is expected to double by 2060, resulting in severe pressures on land. The impact of climate change will not only alter how buildings need to respond to extreme weather events, but it will also play a major role in the types of trees and crops that we grow and demand.

According to UNEP’s Emissions Gap Report 2023, global emissions must be reduced by over 50% by 2030 to be on track for the 1.5°C goal. As part of this equation, reducing embodied carbon is becoming increasingly critical to reducing our environment impact. Embodied carbon is predicted to account for just under 50% of building emissions by 2050, according to the UN Global ABC.

Ideally, there should be more global availability of naturally renewable materials (those that replenish to replace the amount depleted by usage) and sequestrate carbon, as is the case with timber. A sustainable built environment needs to develop a closer relationship with natural materials, moving away from the current linear supply chain interaction to a more symbiotic relationship.

Circularity underpins a sustainable relationship with the natural world

Circularity will be a key requirement in the future. This not only applies to how we design, manufacture and assemble new build housing and infrastructure, but also how we upgrade existing buildings and infrastructure. A key challenge for the sector will be how to maximise the value return from materials and resources used before they go anywhere near landfill.

The operational performance of assets is important as this reduces energy requirements, and correspondingly, carbon impacts. However, the materials used to create these operational improvements, either in terms of building fabric upgrade (primarily insulation) or renewable energy creation (e.g. solar photovoltaic), have an environmental impact. Environmental impacts resulting from the necessary material extraction, transportation and production processes to bring the material into building use must be understood. Consideration of this embodied carbon in materials will be critical in the decision-making process. Building performance upgrades need to be specified with consideration of whole life carbon performance. Given the complexity of the decision-making process and the need for optimum performance, digital twin modelling will also become necessary. Digital twins can ensure accurate information is available for every project context, taking account of local supply chains and environmental impact, as well as correlating the predicted operation performance with actual performance.  

Policymaking in support of a whole systems approach

Government policy is now being shaped to encourage the uptake of sustainable construction materials and this is largely driven by the need to reduce embodied carbon impacts. The recently launched UK Timber in Construction Policy roadmap is one example of this, and there are similar such policies in other European countries, including France, Sweden and Switzerland. Whether these policies are timber specific or require a reduction in use of carbon intensive materials, there is an overarching move towards whole life thinking.

France

As part of the 2024 Paris Olympics, France Bois 2024 was a project launched to promote and increase the use of timber in the construction and development of the new and existing Olympic facilities. This also enabled the Games to reach their climate neutrality goals. The newly constructed athlete’s village takes a hybrid construction approach and uses 45% timber and has resulted in 73 new apartments across three projects.

Sweden

In 2005, Sweden adopted a national wood-building strategy with the aim that 30% of all new buildings within 10–15 years should use a wood-frame and that the number of buildings made out of wood increase by 30% within five years. Stockholm Wood City (Trastad) programme is the latest project. Trastad is an association with the goal of increasing timber in construction to achieve the European climate goals. The proposed development will be the world's largest mass-timber project. It will have 7,000 office spaces, 2,000 homes and cover 250,000 square meters. The district will also feature nature-informed elements and be designed to have the feel of a forest. The development will break ground in 2025, with the first buildings set to be completed in 2027.

Switzerland

The Swiss wood industry has coordinated information from local producers to ensure domestic wood products can be used easily. This work underpins the Swiss Wood Resource Policy target of at least 50% increase in the wood content of the entire Swiss building stock (new buildings) by 2030.

Moving forward with a different mindset

The industry requires transformative change to enable climate-responsible built environments. Responding to these challenges must start now or it will be too late for future generations.

The construction industry should no longer accept the lowest cost or lowest quality forms of delivery and no longer only consider operational performance standards. A whole systems approach goes beyond net-zero carbon. It embraces circularity and takes full cognisance of the broader environmental impacts, such as the methods of extraction and the impacts on biodiversity. An example of this approach in action is Sweden’s first fossil-free preschool.

A cultural shift in the construction industry is required towards collaborative approaches, with shared risk and reward through the procurement and delivery processes. One example of a delivery model is the Integrated Project Insurance, which creates an improved environment for shared risk and reward. This type of collaborative procurement and delivery model will become increasingly necessary given the need to move towards whole life carbon thinking.

Another example of alternative procurement practices is the Edinburgh Home Demonstrator (EHD) project, which is a collaboration of academia, government and industry and designed to accelerate the transfer of knowledge. It transforms research into practical application, testing a new business model for building affordable, net-zero homes to realise the ambition of the Edinburgh and South East Scotland City Region Deal housing programme. Achieving – and then going beyond – net zero requires innovation to be fast tracked into practice and this is only going to be feasible by such collaborative approaches.

The sector will need to embrace innovative models for collaboration and have the collective capabilities necessary to deliver and upgrade existing assets using new methods and regenerative approaches that don’t impinge on the climate or ecological systems in the same way as they do today.

Societal shifts have seen the human population move increasingly from rural to urban environments formed from carbon-intensive materials. The impact of construction practices and our current built environment on climate change must be understood by the wider public. This information can help foster acceptance for the shifts in approach that will be necessary to bring the way we live more into alignment with the natural environment (consuming less than is capable of being produced to sustain how we live). Doing so would unlock social, environmental and economic benefits, including job and wealth creation, human capital and nature-inspired places that can sustain resilient communities in a changing world.