Sustainable construction means building with renewable and recyclable resources and materials and reducing energy consumption and waste. The primary goal of sustainable construction is to reduce the industry’s environmental impact.
Currently, the world is facing a climate crisis. The construction and operation of buildings is responsible for 39% of industrial greenhouse gas emissions [1], with cement alone accounting for 5-8% of the total global emissions [2].
The global construction industry consumes 26% of aluminium output and 50% of steel production [3]. In 2016 alone, the waste produced by the construction and demolition of buildings totalled 136,200,000 tonnes in the UK, and while most of this is recovered, this is recycled into a less valuable product or material.
The Linear Economy
Currently, the construction industry is based on a wasteful economic model that prefers to demolish and rebuild rather than retrofit and repurpose. This is not sustainable. Carrying on in this fashion will require us to continually deplete the earth’s stock of natural resources. This is unsustainable as well as highly polluting.
The opportunities to reduce the built environment’s carbon footprint are clear, as displayed in Figure 1. The carbon reduction potential is maximum when we build nothing – this makes sense. However, continued population increase and changing demands from end-users mean that both new construction and retrofit are essential. Given this, how do we ensure that greenhouse gas emissions are mitigated?
Achieving Sustainable Construction – The Circular Economy
The opportunities to reduce emissions go beyond just building less. Strategies such as designing for disassembly mean that building elements can be taken apart easily. This allows for the component to be reassembled elsewhere, or the constituent parts can be recycled individually.
Additionally, using low carbon materials will be key to achieving net-zero goals. Material emissions, also known as embodied carbon, arise from the extraction and processing of raw materials and transporting, manufacturing and installing building materials on-site, as well as the operational and end-of-life emissions associated with those materials [4].
Materials that use recycled material as a feedstock have drastically lower embodied carbon values and natural materials even less.
In essence, the built environment needs to become regenerative. New (virgin) materials need to be cut out from the beginning of the design process, with our buildings becoming urban mines.
Therefore, the most effective way to achieve the primary goal of sustainable construction and reduce environmental impacts would be to upcycle or retrofit the existing building stock.
For more information on the retrofit, see LETI Climate Emergency Retrofit Guide.
References
[1] IEA, UN Environment Programme, (2019). Retrieved from: Global Status Report for Buildings and Construction 2019 – Towards a zero-emissions, efficient and resilient buildings and construction sector.
[2] EA. (2018). Retrieved from: Technology roadmap—low-carbon transition in the cement industry.
[3] Architects Journal (2019). Retrieved from: Introducing RetroFirst: a new AJ campaign championing reuse in the built environment.
[4] McKinsey and Company (2020). Retrieved from: Data to the rescue: Embodied carbon in buildings and the urgency of now.
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