Performance over people: Mapping the absence of social equity metrics in green roof research

Green roofs provide a diverse array of ecosystem services, yet within the domain of natural and engineering sciences, where green roof research is most situated, performance-related studies are unevenly distributed across thematic dimensions. Socio-economic aspects such as affordability and social equity receive far less attention than technical and biophysical outcomes, despite their importance for public policy, municipal investment, and socially inclusive climate adaptation. Addressing such systemic imbalances first requires acknowledging that they exist. Before solutions are designed, frameworks reformed, or policies reoriented, the field needs evidence that establishes the scale and persistence of the problem. This study provides that foundation by mapping the bibliometric visibility of green roof research across 13 key performance indicator (KPI) categories between 2000 and 2025, using an iteratively refined lexicon-based tagging workflow applied to Web of Science and Scopus records. Stormwater management and thermal or urban heat island mitigation were found to be most frequently tagged, while affordability and social equity remained persistently marginal. Exploratory screening of a broader NBS literature confirmed that socio-economic marginality is general to NBS research but more pronounced in green roof research then in comparable urban interventions. Overall, the study concludes that the literature remains far better equipped to characterise technical performance than to inform affordable, accessible, and socially equitable deployment, underscoring the need for deeper socio-economic integration in future green roof research.