## 2 Literature Review
### Urban Spatial Morphology and Outdoor Environmental Performance  
Urban spatial morphology has been proven to be a critical factor influencing outdoor environmental performance. Research on the interaction between urban morphology and environmental performance dates back to the 1970s, when [PERSON] from Cambridge University studied the relationship between aggregate urban spatial attributes and environmental performance [35]. Since then, the adoption of computational analysis techniques and numerical simulation software has significantly improved research efficiency and reduced costs in this field of study [35; 36; 37; 38; 39; 40; 41]. The quantitative study of environmental performance has seen an increasing diversification of influencing factors, multi-dimensional research scales, and diverse methodologies. The refined influence of spatial elements such as building form factors, density, floor-area ratio (FAR), sky view factor (SVF) [36], and building orientation on urban environmental performance has become a focal area of contemporary research [37; 38; 39]. [PERSON]'s team at the Eindhoven University of Technology proposed a universal computational fluid dynamics (CFD) framework for evaluating wind safety and wind comfort in urban and campus environments and exploring how building density and street width impact urban ventilation [37; 38]. [PERSON]'s team at the Chinese University of Hong Kong investigated the effects of urban morphology factors, such as street network orientation, open spaces, building height, and podium height, on urban potential. They emphasized the importance of planning urban ventilation corridors and led the development of Hong Kong's Air Ventilation Assessment (AVA) technical guidelines [39]. [PERSON]'s team at The Hong Kong Polytechnic University conducted field measurements to study factors influencing outdoor thermal comfort and quantified the effects of direct sunlight, shade, and wind turbulence on thermal sensation [40; 41]. [PERSON]'s team at Sun Yat-sen University used CFD simulations of idealized urban building arrays to summarize how building layouts and height variations influence the efficiency of pollutant dispersion in urban areas [42]. [PERSON]'s team at the Chinese University of Hong Kong applied ArcGIS to propose that maintaining land-use efficiency while controlling building density and height can improve SVF, thereby mitigating the urban heat island effect in high-density cities [43]. [PERSON]'s team at Xi'an University of Architecture and Technology demonstrated using field data that SVF has a decisive impact on solar radiation intensity in urban blocks, with its effect largely determined by the combined influence of street orientation and width [44]. [PERSON]'s team at the Harbin Institute of Technology examined the differential impacts of urban block morphology factors on outdoor temperatures, identifying building coverage, vegetation greening rate, surface material percentage, SVF, and building wall area as the main factors influencing temperature variations [45]. These studies fully demonstrate that urban spatial morphology has a significant impact on urban environmental performance, providing a wealth of theoretical and practical foundations for exploring the relationship between urban spatial morphology and environmental performance. However, certain limitations remain. Firstly, the research objects in these studies are primarily all-age or mixed-age neighborhoods, with optimization goals generally focused on improving overall urban environmental performance, such as enhancing wind environments, mitigating urban heat islands, or increasing air pollutant dispersion efficiency. These studies often fail to adequately address the specific needs of particular demographic groups. Secondly, while existing research focuses on various environmental factors, it lacks a systematic exploration of the unique needs of the elderly. As emphasized in Section 2.1, older adults are more sensitive to outdoor environmental performance.