Impact of green space activity on older adults’ mental health in “double-aging” communities: a case study of Shangcheng District, Hangzhou

With the rapid aging of China’s population, so-called “Double-Aging” communities—characterized by a high proportion of older residents and relatively aged buildings—are becoming increasingly prevalent in urban areas. This study takes Shangcheng District in Hangzhou as a case, systematically examining the effects of community green space, green space activity behaviors, and community renovation on older adults’ mental health across different community types, with particular focus on double-aging communities. Communities were pre-selected based on publicly available government and spatial data, followed by a questionnaire survey yielding 312 valid responses, covering individual characteristics, green space features, activity behaviors, and mental health indicators. Data were analyzed using structural equation modeling (SEM), hierarchical regression, ANOVA, and independent-sample t -tests. Results indicate that green space planning indirectly promotes older adults’ mental health by enhancing overall perception, social interaction, and activity engagement, while social interaction frequency and activity participation have significant direct positive effects. Community renovation significantly improves overall perception and mental health, with pronounced benefits for middle-aged older adults (55–65 years), but limited effects for the oldest group (65 years and above). Moreover, heat-related environmental factors partially attenuate these positive effects. Overall, the findings suggest that optimizing green space planning, improving public environments, promoting social interaction and activity participation, and incorporating heat-adaptive strategies can effectively enhance older adults’ mental health. The study provides theoretical and practical implications for the planning and policy-making of double-aging communities and highlights the need for future research to consider high-aged residents’ adaptability, longitudinal analyses, and the integration of multidimensional environmental factors.