Circular Construction: Three ways circularity drives decarbonisation of the built environment

The UK’s built environment, including the construction and operation of buildings, contributes to around one third of emissions. So far, efforts to deliver the sector’s net zero ambitions have largely focused on operational emissions. However, if the industry is to grow, build more and emit less, it needs to become circular and tackle the emissions embodied in materials, equipment and services.

75%

Total floor area is set to grow approximately 75% from 2020 to 2050
x3

The built environment needs to reduce its emissions by more than three times by 2035
50%

Circular approaches have the potential to reduce greenhouse gas emissions by 50%

Investment, Innovation and Collaboration

“By implementing circularity, the construction sector has a unique opportunity to lock up emissions for the long term and respond to social needs for quality affordable housing at the same time. We are already seeing new technologies and evolving business models provide an opportunity to find where economic and environmental value converge.“

_{Melissa MacEwen

Circular Economy Lead Asia Pacific, PwC}

The UK has seen its built environment emissions drop by 37% between 1990 to 2018, primarily through retrofitting and improvements in heating efficiency and insulation. This focus on operational emissions is encouraging and will continue as investments are made to phase out fossil fuel boilers and to increase the uptake in heat pumps and more efficient appliances. But, to achieve net zero, businesses in the construction sector need to confront embodied emissions which are harder to reduce.

Steps are already being taken as businesses increasingly recycle materials, particularly in cement and steel production. But, the headroom for further impact through recycling is more limited. To significantly reduce emissions, the construction sector needs to increase their focus on underlying production processes and become more circular by design, increasing the direct reuse of materials where possible. This requires substantial investment and improved collaboration across the value chain.

“To meet its net zero ambitions, the construction sector needs to shift its focus beyond regulatory requirements, build sustainable partnerships across the value chain and reassess how things are manufactured at source.”

_{Paul Sloman

Partner, Head of Engineering and Construction}

Alternative fuels and processes can reduce emissions and help to decarbonise cement and concrete. Critical to this is decarbonisation of the underlying energy grid, and carbon capture technologies. Many of the same challenges exist for steel but this is an even more technically challenging and expensive process. Moving away from basic oxygen steelmaking to electric arc furnaces and green hydrogen production is key to decarbonising steel and enables recycling and reworking steel to further reduce emissions.

Investment in this area will not start on its own and businesses and investors need a degree of certainty in the cost of not investing. This can be financial (through taxes or tariffs) or regulatory (fines), but without a marker to price carbon investment, landlords, investors, and construction businesses could struggle to make material progress. Collaboration is critical to pool resources, talent and knowledge across the market.

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Three actions for the construction sector

Design with circularity in mind

Bringing circular thinking to the design stage of construction is key. This is most important for embodied carbon - the ability to reduce embodied emissions reduces rapidly as construction begins. Embedding circularity early in a project is increasingly becoming a priority for construction businesses. Emerging regulations require upfront carbon life cycle and whole of life assessments which are starting to move circularity up the agenda, and earlier in the project planning and design process.

To design for a circular future, businesses need to consider the use of sustainable materials (including the availability of recycled or reused materials) and should consider switching to new construction processes. The cost implications can be challenging, but initiatives such as modular methods of construction are a great example as constructing off-site can save materials and time, at a more manageable cost.

Designing with a view to reuse can also improve the condition of recovered materials, and also make existing structures last longer. For example, developers can use digital twins, which are advanced technology models of buildings often developed alongside the original design. By mapping out the materials used, digital twins can optimise the quantity of materials used and help pre-demolition audits to locate and assess the suitability of materials for recovery and reuse. This technology also stores and calculates the material’s future strength and corrosion levels enabling developers to make informed decisions around reusing steel, glass or concrete so that they can build more sustainably.

Increase structure lifecycles through retrofitting

Lengthening the useful life of existing materials and buildings is ultimately the goal of circularity. The construction sector should also consider how buildings can be retrofitted to reduce emissions in the long term. Buildings may have a variety of different uses and users in the future and being able to switch and interchange for different purposes is key.

Through retrofitting, the construction sector can increase building lifecycles by designing them to adapt to different user needs such as offices, residential or for commercial purposes. This reduces the need for demolition and for new construction, eliminating two processes that generate significant carbon emissions.

Recycle and reuse materials

Where retrofitting buildings isn't an option, deconstruction may be unavoidable. But, there are ways to still reduce emissions by isolating materials that can be recycled or reused.

When demolition is required, recycling and recovery process must improve to ensure that, materials can often need to be broken down or fed back into production processes which generate high emissions. Reusing materials directly could be a lower cost and faster solution, as it often requires less reprocessing or reworking and can drive circularity further. The limiting factor today is confidence in used materials, which could be solved through materials passports.

The London Olympic Stadium is a great example of circular construction through direct reuse. With 2,500 tonnes of repurposed steel tubing used they were able to reduce their carbon footprint and lower costs.

“The construction sector must find a way to both deliver the buildings our economy and society needs, and achieve its net zero ambitions.Taking a circular approach to tackling embodied emissions will be crucial.”

_{Chris Temple

Partner, Net Zero Transformation Leader, PwC UK}