Biodiversity offsetting is the practice of providing compensation for ecological resources which are lost or damaged by development, by creating or improving equivalent or better habitat on another site. Government policy supports this approach, and readers may recall a furore last year when it was suggested that this could be a charter for the destruction of irreplaceable habitat such as ancient woodland. Pilot projects have been run in various areas, and the results are currently being assessed. A good practical example of how offsetting can work is provided by a recent planning appeal in respect of a housing development in the village of Thaxted, Essex. Uttlesford District Council had refused permission on the basis that the development would be contrary to para. 118 of the NPPF, in that it would result in the loss of unimproved grassland, which had the potential to improve to lowland meadow status. The appellants were however able to convince the local planning authority that proposed offsetting would avoid the development causing significant harm to biodiversity, so that the authority dropped its objections at the inquiry.

Evidence emerged that the site had been subject to arable usage in the 1970s, which would have seriously affected its quality as grassland. Without active intervention and management, the grassland interest of the site would decline, and it certainly would not improve to lowland meadow status. An offsetting site was found at a farm within the district, where suitable management could improve the quality of the grassland resource to lowland meadow status. The appellants’ case was supported by expert evidence on ecology and on land management and also by assessment undertaken objectively by the Environment Bank as to the number of “conservation credits” needed to compensate for the loss of the appeal site and the number that would be provided by the offsetting site. This quantitative approach is important in providing objectivity and assurance as to the adequacy of compensation.

The appellants and local planning authority agreed before the inquiry a suite of documents to ensure delivery of the offsetting site and its improvement and monitoring over a 25 year period. These included a section 106 agreement with the owners of the appeal site, a section 106 with the owner of the offsetting site, a management agreement between the appeal site and offsetting site owners, and a 25-year management plan for the offsetting site. The offsetting arrangements were in addition to onsite mitigation for bats, reptiles and other wildlife features. The planning authority agreed that these measures, taken together, meant that the proposal was in accordance with para. 118 of the NPPF and did not give rise to significant harm.