Innovative Thinker | Eva MacNamara
Impact control
Civil engineers should consider the biodiversity impact of the materials they specify, Eva MacNamara tells Sotiris Kanaris.
The triple planetary crisis refers to three main interlinked issues: climate change, pollution and biodiversity loss – the reduction or eradication of animal and plant species. According to the World Economic Forum’s New Nature Economy Report II: The Future Of Nature and Business, published in 2020, threats from infrastructure and the built environment affect 29% of vulnerable species globally.
MacNamara: engineers must assess the embodied biodiversity impacts of a material’s whole lifecycle
The government is aiming to address this with the Biodiversity Net Gain (BNG) legislation which will be implemented in England for housing, industrial and commercial developments in January 2024 and for Nationally Significant Infrastructure Projects in 2025.
BNG is achieved when a site’s biodiversity value increases after construction is complete.
BNG legislation will make it mandatory for projects to achieve at least a 10% increase in on-site biodiversity on completion compared with a baseline calculated at the predevelopment stage. This increase will be calculated using the Biodiversity Metric 4.0 developed by the Department for Environment, Food & Rural Affairs. It covers ecological characteristics such as the size, condition and location of the habitat.
Expedition Engineering associate director Eva MacNamara welcomes the introduction of the new legislation, but believes it will not be enough to make the sector’s overall contribution to biodiversity positive.
“The 30% biodiversity loss [caused by the built environment sector] is not just from site boundaries,” she says, pointing to the impact from the extraction, manufacturing, transport and disposal of raw materials.
She says the sector should consider “embodied biodiversity impacts” which result from the processes that take place throughout a material’s lifecycle and which are not covered by other biodiversity metrics such as BNG.
She was the research director for the Embodied Biodiversity Impacts of Construction Materials report published in September by Expedition Engineering with funding from the ICE.
“Materials specification has historically not been looked at through the lens of biodiversity“In current thinking the civil engineer has no impact on biodiversity, as the biodiversity net gain on site is usually determined by others,” says McNamara.
“Materials specification has historically not been looked at through the lens of biodiversity.”
She stresses that civil engineers could reduce biodiversity loss through their materials choices.
The report outlines four initial actions that built environment practitioners could take to reduce the biodiversity impacts of materials they use in their designs. These are: minimise materials needed; prioritise reused materials; use existing responsible sourcing and certification schemes; and understand where materials have been sourced.
It also calls for a strategic route map to provide practitioners with the capability, opportunity and motivation to address their contribution to tackling the biodiversity crisis.