A Delphi-AHP-QFD Approach to All-Age-Friendly Renewal of Outdoor Public Spaces in an Old Industrial Community

China’s urban development model has shifted from incremental expansion to a new phase focused on improving the quality of existing infrastructure, and the revitalization and management of older neighborhoods have become one of the key priorities in current urban renewal efforts. Outdoor public spaces in older neighborhoods serve as vital venues for residents’ daily lives and social activities and are crucial to their safety and quality of life. However, many older neighborhoods face issues such as aging infrastructure, limited spatial functionality, conflicts between pedestrians and vehicles, poor accessibility, and a decline in community culture. This study focuses on the employee residential area of the Sanming Iron and Steel Plant in Fujian Province and constructs a framework that integrates the Delphi method, the Analytic Hierarchy Process (AHP), and the Quality Function Deployment (QFD) methodology. Identify residents' needs from an age-inclusive perspective and translate them into reasonable and feasible design requirements. First, field investigations, resident interviews, and expert consultations were used to identify the main problems of the outdoor public spaces. Second, two rounds of Delphi consultation were conducted to construct and refine an evaluation indicator system, resulting in six first-level indicators and twenty-five second-level indicators. Third, the Analytic Hierarchy Process was applied to assign weightings to user requirements, and Quality Function Deployment was used to transform these needs as design priorities. The results show that safety and risk resilience, accessibility and universal design, and age-inclusive activity support are the most important dimensions of renewal. At the design-requirement level, age-inclusive and universal design, lighting-system improvement, clear road organization, and safety and emergency facilities received the highest priorities. Based on these findings, three renewal strategies are proposed: reorganizing slow-traffic systems to reduce pedestrian–vehicle conflicts; introducing modular and time-sharing spatial design to support intergenerational use; and improving landscape quality while reactivating industrial collective memory. This study provides a need-oriented and traceable methodological framework for the revitalization of outdoor civic areas in aging industrial communities and offers practical references for all-age-friendly urban regeneration.