A value tree approach to integrate policy and legislation into spatial decision support tools for siting offshore renewables

Finding space for offshore renewable energy developments requires accounting for multiple objectives that consider technical factors as well as environmental and socio-economic interests. To aid decision making, multi-criteria mapping can be used, which combines a set of spatial data layers representing multiple objectives into one overall suitability map. Multi-criteria mapping should consider existing policy and legislation in place if it is to reduce consenting risk, but this is not yet common practice. To establish an auditable link between policy and legislation requirements and multi-criteria mapping tools, the effectiveness of a value tree approach was evaluated. Linking the policy and legislation requirements directly with the included layers of an existing tool gave an indication of how ‘mappable’ are planning policies and legislation that are currently in place, and it was found the policies could be interpreted in different ways. Additionally, some policies were underpinned by more binding and specific legislation than others. The value tree approach provides an opportunity to ‘test’ future planning policies to ensure they are specific enough to be implemented with spatial decision support and consequently, their utility in consenting decisions.