Should different impact assessment instruments be integrated? Evidence from English spatial planning

This paper aims at providing empirical evidence to the question as to whether integration of different instruments is achieving its aim in supporting sustainable decision making, focusing on SEA inclusive sustainability appraisal (SA) and other impact assessments (IAs) currently used in English spatial planning. Usage of IAs in addition to SA is established and an analysis of the integration approach (in terms of process, output, and assessor) as well as its effectiveness is conducted. It is found that while integration enhances effectiveness to some extent, too much integration, especially in terms of the procedural element, appears to diminish the overall effectiveness of each IA in influencing decisions as they become captured by the balancing function of SA.

► The usage of different impact assessments in English spatial planning is clarified.
► The relationship between integration approach and effectiveness is analyzed.
► Results suggest that integration does not necessarily lead to more sustainable decisions.
► Careful consideration is recommended upon process integration