Open Access

Joachim Spangenberg, Sylvia Lorek

• It is increasingly obvious that for safeguarding environmental sustainability, eco‐efficiency measures will need to be complemented by sufficiency, in particular by strong sustainable consumption. The Theory of Planned Behaviour TPB and Social Practice Theory SPT offer different views on consumer behaviour, and on ways to change it. This paper briefly describes the challenges, discusses the applicability of both theories and their meaningfulness for policy recommendations. We suggest an approach combining results of both bodies of theory, complemented by ideas from political economy, to substantiate the Prism of Sustainable Consumption we introduce as a heuristic sufficiency policy tool. It is useful to identify affordability criteria for change in each dimension, as the basis for deriving suggestions for effective policy interventions. We conclude that (i) effective interventions are possible, (ii) they have to address several dimensions of affordability simultaneously, and (iii) the sufficiency policy space prism can be a useful tool in structuring planned interventions.