Are consumers consistent in their sustainable behaviours? A longitudinal study on consistency and spillover

It is unclear whether knowledge about a customer’s current sustainable behaviours, such as their choice of lightbulbs or travel mode, allows us to predict the sustainable behaviours they will carry out in the future. We address this in a large longitudinal study (N = 2177) where participants provided self-reports on electricity-, heating- and mobility-related consumption at two separate times, three years apart. The results highlighted a high level of temporal consistency, whereby carrying out one sustainable behaviour predicted consumers would be carrying out the same behaviour three years later. However, sustainable behaviours generally did not drive other different sustainable behaviours years later (i.e. no spillover). In fact, isolated instances of spillover emerged only between different kinds of mobility-related consumption among consumers with high environmental values. Overall, the findings indicate a high degree of consistency in sustainable behaviour even years apart, and limited spillover from one sustainable behaviour to another.