Participatory sustainability assessment for spatial planning: reflections from a pilot exercise in Flanders, Belgium

Sustainability is both an appealing and bewildering concept, subject to a range of interpretations. While this plurality of views can lead to innovative policy solutions to complex societal challenges, it can also lead to confusion and even decision paralysis. If sustainability is to guide decision-making, practical and user-friendly participatory decision-support processes are required. Sustainability assessment allows to systematically integrate sustainability considerations in decision-making. Flanders, Belgium's northern region, has seen a recent boost of public policy initiatives for sustainability, which includes a stated interest in exploratory sustainability assessments in which the public can be included. A tailor-made approach, based on a modified nominal group technique (NGT), was developed and applied. The NGT-based exploratory sustainability assessment consisted of two rounds during which participants were asked to reflect first individually, and then collectively, about sustainability implications of spatial planning policy documents. The participants stressed the adaptability and user-friendliness of the approach, but also emphasized the difficulty to identify clear sustainability trade-offs. NGT does not allow for a full sustainability assessment on its own, but this pilot exercise shows it can be used as an exploratory sustainability assessment, which can be complemented with other methods and inputs in a later stage of decision-making. We provide a critical reflection on NGT, as a simple yet innovative method in support of participatory sustainability assessment.