8 THE CLIMATE CHALLENGE Bracing for biodiversity
Environmental planning specialist Jaquelin Clay speaks to Housebuilder and Developer’s Jack Wooler about how housebuilders need to address challenging national and local planning policy targets on enhancing biodiversity.
iodiversity Impact Assessment Calculation provides a real challenge to housebuilders and developers, with planning policy affecting builders of all sizes. The benefits of increased biodiversity, however, can be significant.
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Under the latest NPPF (2019 V3 para 170 d), planning policies and decisions should aim to minimise impacts of development on biodiversity, while striving to provide net gains in biodiversity and enhance the natural and local environment. The Environment Bill, currently in Parliament, will mandate a minimum 10 per cent uplift in biodiversity, which can be evidenced through the biodiversity metric. Jaquelin Clay, practice principal of JFA Environmental Planning, explains that the metric is a computer model designed to calculate the net change in biodiversity units, post-development.
She comments: “Data input is based on a pre-development habitat survey using standardised habitat classifications. Data post-development is input, using information from the application master plan. An algorithm is then applied, within the model, that calculates the net biodi- versity units for the development. This results in a numerical score for the proposals, which can be either negative or positive.”
DEFRA’S METRIC
When discussing the new biodiversity metrics, Clay tells me that the main advantage of the DEFRA Metric 2.0 is “that it will quantify enhancement measures in a way that will make it difficult to argue that they are not sufficient.”
She continues: “In practice, we have found a 10 per cent uplift is not particularly difficult to achieve. Most projects require sufficient green
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infrastructure, open space and so forth to provide the basis for enhancements. “On a cautionary note, the competent authority does not have to limit itself to the BIAC in analysing biodiversity net gain. I expect in practice it will do, at least at first.”
She tells me that one of the inputs to the data analysis is a condition score for the habitat, again post-development. This is based on assumptions as to the quality of the enhancement measures and long- term management.
“It may be necessary to justify post- development construction scores based on submitted Landscape and Ecology Management Plans or Ecological Mitigation Strategies,” Clay continues. “These are commonly required as Reserved Matters, but with the Environment Bill, it may be necessary to provide these at the application stage.”
SIZE MATTERS The practice principal tells Housebuilder and Developer that increasing biodiversity can mean different approaches depending on the size of development in question. In
larger scale projects, for example, the provision of relatively large areas of open space (in excess of 1 hectare) “would certainly be beneficial.” For a large development with insufficient on-site capacity however, Clay says it may be necessary to provide compensation off site, at a distance from the development: “This is not ideal, but could be acceptable. Larger sites could support a better range and quantity of native trees, native hedgerows could either be retained or added as a frame- work for the development.” For a mid-scale development, “say 50-100 units,” she says, open spaces could be a mixture of informal recreation and wildlife land use. Small tree groups could be provided, and native planting in boundary treatments could be used. “Ponds can also be incorporated into mid-scale developments with ease, and pre-existing water bodies can be retained and often greatly improved by means of conservation management,” she adds. In both large and mid-sized
development, Clay believes that the use of SuDS as nature conservation areas
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