A Sustainability Appraisal is a systematic process that must be carried out during the preparation of Local Plans and Spatial Development Strategies. Its role is to promote sustainable development by assessing the extent to which the emerging plan, when judged against reasonable alternatives, will help to achieve relevant environmental, economic and social objectives.
This process is an opportunity to consider ways by which the plan can contribute to improvements in environmental, social and economic conditions, as well as a means of identifying and mitigating any potential adverse effects that the plan might otherwise have. By doing so, it can help make sure that the proposals in the plan are appropriate given the reasonable alternatives. It can be used to test the evidence underpinning the plan and help to demonstrate how the tests of soundness have been met. Sustainability appraisal should be applied as an iterative process informing the development of the plan.
Section 19 of the Planning and Compulsory Purchase Act 2004 requires a Local Planning Authority to carry out a sustainability appraisal of each of the proposals in a plan during its preparation. More generally, section 39 of the Act requires that the authority preparing a plan must do so “with the objective of contributing to the achievement of sustainable development”. There is a separate requirement for Spatial Development Strategies be accompanied by a sustainability appraisal under regulation 7 of both the Town and Country Planning (London Spatial Development Strategy) Regulations 2000 and the Combined Authorities (Spatial Development Strategy) Regulations 2018.