Bridging environmental, economic, and social gaps in green wall retrofitting: Evidence from Al Ain, UAE

This study investigates the integration of modular green walls with conventional stone cladding as a holistic retrofitting strategy for Emirati housing in a hot-arid climate. The study advances retrofit engineering practice by integrating building-energy simulation, carbon quantification, capital cost modelling, irrigation feasibility analysis, and VR-based participatory assessment into a unified environmental–economic–social evaluation framework. A representative public villa in Al Ain, United Arab Emirates, was selected as a case study. Three retrofit scenarios were modeled using DesignBuilder: (S1) 100% insulated stone cladding, (S2) 60% insulated stone + 40% insulated modular green wall, and (S3) 60% insulated stone + 40% uninsulated modular green wall. Cooling Energy Use Intensity (EUI), operational CO₂ emissions, capital cost, irrigation feasibility, and social acceptance were jointly assessed through building-energy simulation, a market-based cost model, condensate-fed drip irrigation analysis, and virtual-reality (VR) e-participation with 21 residents. Relative to the baseline (262.89 kWh/m²·year), S1 reduced cooling EUI to 161.69 kWh/m²·year (38.5%). For the hybrid scenarios, method-dependent values ranged from 161.24 to 162.72 kWh/m²·year for S2 and from 168.52 to 173.13 kWh/m²·year for S3, corresponding to energy reductions of approximately 38.2–38.6% and 34.2–35.9%, respectively. Operational CO₂ reductions ranged from approximately 14.3 to 16.2 t/year. The hybrid insulated stone–green wall configuration (S2) showed overlapping thermal performance with S1 while lowering total capital investment and delivering a simple payback of approximately 13.5–13.7 years. Under the seasonal irrigation model, condensate reuse supplied approximately 80% of annual irrigation demand on an annual-average basis, with seasonal variation interpreted through a simplified three-season water-balance model.