Innovative methodology developed by ICE-backed researchers paints damning picture of effect of steel and concrete on habitats and species
Researchers have developed an innovative methodology for the assessment of construction material impacts on biodiversity, intended to go beyond the existing focus on building sites set out under Biodiversity Net Gain (BNG) legislation.
Dubbed ‘Embodied biodiversity impacts’, the approach is a key output of a report by engineering consultancy and social enterprise Expedition Engineering, supported by the Institution of Civil Engineers (ICE) Research and Development Enabling Fund.
Biodiversity is declining more rapidly than at any time in human history. We have entered the sixth ‘mass extinction event’ and The World Economic Forum has identified construction as one of three systems responsible for over 80% of global biodiversity loss.
New BNG regulations that come into force in January require developers to demonstrate a minimum 10% net increase in on-site biodiversity on completion of a development, compared with a pre-development baseline.
Expedition Engineering argues that this fails to take account the impacts of construction materials that make up assets, which typically require raw materials to be extracted, manufactured, transported to site and eventually reused, recycled or disposed of.
Researchers propose ‘Embodied biodiversity impacts’ as a way for practitioners, including architects, to describe every process throughout a material’s lifecycle not covered by other metrics, such as BNG.
Analogous to embodied carbon, impacts would depend ‘to a greater extent’ on local factors, say researchers, including local habitats, species and environmental receptors. For example, quarrying limestone in a tropical location might risk damage to the habitat of a specific critical species not present in other quarrying areas. And unlike carbon, ‘a multifaceted framework is required to truly understand embodied biodiversity impacts.’
Eva MacNamara, project director and associate director at Expedition Engineering, said: ‘The impact of embodied biodiversity is likely to be many times what is currently considered in Biodiversity Net Gain calculations. Architects can make a fundamental difference to this by accelerating the uptake of circular reuse principles, reducing the impact from extraction. Circular economy principles are a win for both carbon and biodiversity impacts; architects need to set that scene from project inception.’
The methodology enables practitioners to make a qualitative assessment of embodied biodiversity impacts based on four of the five ‘key pressures’ identified by the United Nations as driving biodiversity loss. These are land-use change, direct exploitation of species, pollution and invasive species.
The appraisal is carried out over four stages, covering defining material assumptions; mapping high-level lifecycle processes’ identifying evidence of impacts on biodiversity; and rating the likely severity of impact.
In applying the methodology to concrete, researchers found high severity impacts related to sand/gravel extraction and rock mining. Medium severity impacts came from limestone and kaolin clay extraction and cement manufacture, among others.
‘The quarrying and the dredging of raw materials for cement and aggregate, including limestone, clay and rock, can damage or remove habitats,’ the report states. Cement production ‘can cause air and water pollution’ and while UK emissions are regulated by the Environment Agency and continuously monitored, publicly available records of monitored levels ‘were not easily found’.
Turning to steel, the report found high severity impacts from iron ore extraction, coking coal extraction and materials transport to steelworks. Medium severity impacts were attributed to limestone extraction and preparation for reuse, among others.
Steel requires the raw extraction of coking coal, limestone and iron ore through mining and quarrying, which researchers note ‘can damage or remove habitats, cause groundwater contamination and make sites more prone to invasive plant species’.
Furthermore, there is evidence of iron ore and coking coal mining having significant impacts on biodiversity in locations from which the UK imports, including Sweden and Canada. Processes for recycling and cleaning steel for reuse can cause water pollution.
Timber fared much better in the analysis, with the only high or medium severity biodiversity impacts found in the forestry management and harvesting stage. The main impact of sawmills on biodiversity is ‘likely to be via long-term climate change due to energy use,’ said researchers. Sawmills in the UK have made carbon commitments and many are moving to low-carbon fuels.
Expedition Engineering describes the research as ‘an initial scoping piece’. It says a routemap for further development should include efforts to map complex global systems, such as developing material flows within supply chains, and to understand regulation and commitments.
In addition, it calls for the creation of clear boundaries for analysis, in terms of lifecycle stages and impacts, and more work to define an approach to quantifying biodiversity impacts ‘to account for the multifaceted nature of the impacts and the level of certainty of impact, particularly where evidence is limited’.