Balancing thermal comfort, construction feasibility, carbon emissions, and cost: multi-criteria evaluation of passive retrofits for high-rise social housing

• New multi-criteria framework for evaluating passive retrofits in high-rise housing. • Retrofit performance is assessed under current and projected 2050 RCP 4.5 climates. • West-facing, middle, and upper-level units showed the highest heat vulnerability. • Overhang shading plus mineral-wool is the most thermally resilient scenario. • Reflective paint plus mineral-wool is the most feasible, green, and low-cost option. Residents of affordable housing apartments often experience significant thermal discomfort due to poor insulation and the absence of HVAC systems. A warming climate, energy poverty, and associated health risks further exacerbate this vulnerability. Passive thermal retrofits offer potential improvements but require evaluation across multiple technical, environmental, and economic criteria. This study conducts a comprehensive assessment of passive retrofit performance for two high-rise government-subsidized housing buildings in Sydney, Australia. Building energy modelling (BEM) was used to simulate retrofit performance under current and projected 2050 (RCP4.5) climate conditions, enabling future-oriented evaluation of thermal resilience. The analysis integrates thermal comfort by orientation, floor level, and season with construction feasibility, environmental impacts, and cost, generating both criterion-specific and overall rankings through a Weighted Sum Model (WSM). This multi-criteria framework supports transparent, flexible, and stakeholder-sensitive decision-making. Findings indicate that west-facing units, followed by east-facing units, exhibit the greatest thermal discomfort annually and across all seasons, while middle and upper levels are more prone to overheating. Among retrofit scenarios, overhang shading combined with external mineral wool insulation (OS + MW) ranked highest when thermal comfort for both hot and cold periods was prioritized. In contrast, reflective paint with mineral wool (RP + MW) offered the most favourable feasibility, environmentally friendly, and cost-efficient profile. The proposed framework provides a transferable method for improving thermal resilience in high-rise social housing