Development of a ranking of barriers to the adoption of green roofs in Brazil using Delphi methodology

Green roofs can contribute to mitigating urban heat islands, managing stormwater, and improving the environmental performance of buildings, however, their adoption in Brazil remains incipient. Although previous studies have examined green roof barriers in different countries, the Brazilian context remains insufficiently characterized in terms of expert-based prioritization, particularly given the absence of official market statistics, the lack of a dedicated national technical standard, and the early-stage development of public policies and incentives. This study produces an empirically validated context-sensitive ranking of green-roof adoption barriers in Brazil by combining a structured literature search based on the ProKnow-C protocol with an iterative Delphi panel of Brazilian experts conducted until simultaneous convergence criteria were met. Its contribution lies in situating the prioritization within the specific institutional, technical, and informational conditions that constrain green roof diffusion in Brazil, and in enabling structured comparison with international evidence to distinguish universally reported obstacles from context-amplified constraints. Prioritization was estimated using the Relative Importance Index, and consensus was verified through pre-defined thresholds for median, interquartile range, coefficient of variation, and Kendall's concordance coefficient. Twenty barriers were identified and grouped into five categories. The results indicate that adoption is predominantly constrained by informational deficits and economic and institutional barriers. The five highest-ranked barriers were gaps in public knowledge, lack of public incentives and governmental support, increased design and construction costs, low environmental awareness, and insufficient performance data. Comparison with international studies reveals convergence regarding the role of costs and incentives, but informational barriers assume greater centrality in Brazil, reflecting the early diffusion stage of the technology and limited local performance evidence. These findings provide an empirical basis for public policy design, professional training strategies, and applied research agendas targeting the priority constraints on green roof adoption in Brazil.