Evaluating the Effects of Vertical and Roof Greenery on Pedestrian Outdoor Thermal Comfort: A Systematic Review

Urban heat stress threatens pedestrian thermal comfort in dense cities, amplified by climate change and urban form, yet the interactions between green roofs and vertical greenery systems and their implications for human thermal comfort remain insufficiently explored, as most studies examine them separately without human-centered outcomes. Following PRISMA 2020, this systematic review analyzed 144 articles retrieved from Scopus and Web of Science (search conducted in December 2025) covering the period 2020–2025 through bibliometric mapping, of which 46 studies were selected for qualitative synthesis. The review addresses three questions: (1) What are the individual and combined effects of green roofs and vertical greenery systems on pedestrian-level thermal comfort? (2) Which microclimatic mechanisms of green roofs and vertical greenery systems influence the physiological and perceptual responses of pedestrians? (3) How does urban morphology (street canyon geometry, building density, orientation) modulate the effectiveness of these green interventions? An integrated conceptual framework replaces linear cause-and-effect thinking with a systemic view where outdoor thermal comfort associated with green roof and vertical greenery interventions is understood as the convergence of human physiological, psychological, behavioral, and socio-cultural responses, with urban morphology as a key regulator and human adaptation as the central axis. This framework reveals that pedestrian responses vary across these dimensions; thus, no single solution fits all contexts. Effective cooling strategies must be assessed within specific climate zones and behavioral settings, replacing one-size-fits-all with context-specific, human-centered design. This framework underscores that nature-based solutions must be human-centered, providing a robust foundation for future research and policy. The findings are limited by an uneven geographic/climatic distribution of the reviewed evidence and a predominant reliance on indoor or laboratory-based evidence for fine-grained human physiological and psychological responses.