Pro-social versus pro-self motivations for green roof adoption: Evidence from a discrete choice experiment

Green roofs are a promising Nature-Based Solution (NBS) for urban climate adaptation, yet their adoption remains limited due to multiple factors, including mixed incentives between private and public benefits. This study investigates the impact of information nudges on public preferences and willingness-to-pay (WTP) for green roof co-benefits in the Netherlands. Using a split-sample ( n = 2173) Discrete Choice Experiment (DCE), we examine how highlighting private (e.g., indoor cooling, roof lifespan) versus public (e.g., biodiversity, flood risk reduction) benefits influences WTP. The results show that respondents value green roof benefits overall highly. Information nudges significantly affect WTP for specific attributes. In particular, the Pro-self treatment, that communicates the private benefits of green roofs, increases WTP for indoor cooling and flood risk reduction, while the Pro-social treatment, communicating the public benefits, positively influences preferences for biodiversity improvements. Our findings suggest that even when information emphasizes private benefits, it can simultaneously enhance WTP for collective outcomes, likely due to perceived spillover effects. The preferences also display a high level of heterogeneity, indicating diverse valuation patterns within the population. The study further highlights that focusing individuals on their private gains is an effective strategy to increase their support for green roofs. This result is particularly salient for households that rank low on the altruism scale. Additionally, the high demand for biodiversity suggests that cost-benefit analyses should account for non-use values when evaluating green roof policies.