Energy Profiling and Thermal Assessment of Low-Cost Vertical Housing in Warm-Humid Surabaya: Strategic Pathways Toward Net Zero Energy Buildings in Indonesia

Indonesia’s rapid urbanization has intensified housing demand, making multi-story public housing (Rusunawa) a key solution for low-income communities. However, the reliance on mechanical ventilation and air conditioning significantly raises electricity consumption, posing challenges to the national target of Net Zero Energy Buildings (NZEB) by 2050. This study evaluates energy profiles and proposes efficiency strategies for four Rusunawa complexes in Surabaya, using a mixed-method approach that includes on-site thermal measurements, surveys of 163 households, and scenario-based modeling. The analysis identifies cooling, lighting, and cooking appliances as primary energy drivers, exacerbated by poor passive design and occupant behavior. Simulation results show that utilizing 30% of rooftop area for photovoltaic (PV) systems can fully meet or exceed daily electricity demand, with some sites achieving over 1,400 kWh/day in surplus. Load-shifting strategies further enable power class reductions, lowering tariffs and operational costs. The study provides practical, scenario-based recommendations combining renewable energy integration and demand management. These findings offer a scalable pathway toward NZEB implementation in Indonesia’s low-cost housing sector.