## 1 Introduction  
The proportion of the global population aged 60 and above is steadily increasing and is projected to rise from 12% to 22% by 2050 [1]. This trend is particularly pronounced in China,where the proportion is expected to reach 33.0% by 2050 [2]. In this context, the importance of improving the health and well-being of the elderly is becoming increasingly apparent. The Chinese government has proposed relevant strategies and goals, emphasizing the urgency of improving the quality of life for older adults [3].  
With the continuous increase in the number of facilities such as nursing homes, senior communities, and day-care centers [4], significant progress has been made in research on the indoor environments of senior care buildings. These studies cover various aspects, including barrier-free design [5], improvements in indoor thermal comfort [6], enhancements in indoor air quality [7], and the optimization of lighting environments [8], all aimed at improving the living experience and quality of life for the elderly. However, while improvements to indoor environments are important, focusing solely on them is insufficient to fully enhance the overall quality of life for the elderly. The outdoor environment also has a profound impact on their quality of life [9].  
A comfortable outdoor environment helps increase the frequency and duration of outdoor activities for the elderly, promoting social interaction and recreational activities [10], thereby improving mental health, alleviating loneliness [11; 12], and reducing the incidence of cognitive impairments and Alzheimer's disease [13; 14]. However, with aging, the elderly experience significant declines in physical function, immune capacity, cognitive abilities, and adaptability to environmental changes [15; 16; 17; 18]. Their activity range gradually shrinks, yet their environmental demands continue to rise [19; 20; 21].  
At the same time, psychological changes occur, making the elderly more prone to feelings of loneliness [22], isolation, and fear of abandonment by society [23]. Therefore, they are more eager to engage in social interactions [24] and participate in community activities [25] to contribute their value. In this process, outdoor spaces in residential areas become important venues for elderly individuals to engage in social activities, participate in events, and exercise [19; 20].  
Therefore, optimizing the comfort of outdoor environments in residential areas is not only key to improving the quality of life for the elderly but also an effective measure to address the challenges of population aging. Through scientific planning and design, creating pleasant outdoor environments for the elderly can significantly enhance their life satisfaction and well-being, while also contributing to social progress and development.  
Based on the above context, this study employs a multi-objective optimization approach to explore optimal block morphology layouts. The study aims to reveal the nonlinear relationships between block morphology and environmental performance, identify key morphological indicators, and optimize early-stage block layout decisions to reduce the cost of later-stage retrofitting. The research findings will provide strategic support for designing elderly-friendly blocks and offer guidance for both the theory and practice of block morphology optimization through the integration of parametric modeling, performance simulation, and machine learning.