Optimising HVAC Setpoints Based on Occupant Neutral Temperatures in a Green-Certified Office Building in a Hot Climate: An Energy Simulation Study

Green buildings in hot climates are increasingly reported to overcool occupants when operated according to prescriptive international thermal comfort standards, resulting in both occupant dissatisfaction and avoidable energy waste. This study investigates the energy performance implications of aligning HVAC cooling setpoints with occupant-derived neutral temperatures in a LEED-certified office building in Abuja, Nigeria. A companion post-occupancy evaluation (Muhammad et al., 2025) was conducted through indoor environmental measurements and occupant thermal sensation surveys using the ASHRAE 7-point scale, from which neutral temperatures were derived using the Griffiths method. That study revealed a 2.2°C discrepancy between the operative temperature (24.3°C) and the occupant-derived neutral temperature (26.5°C), indicating systematic overcooling. Building on those findings, a dynamic thermal simulation model was developed in DesignBuilder and calibrated against actual energy consumption data (MAPE = 7.98%). Two scenarios were then simulated: a baseline at 24.3°C and an adjusted scenario at 26.5°C. Results show that this 2.2°C setpoint adjustment better aligns indoor conditions with occupant comfort preferences while yielding a 7.61% reduction in total annual energy consumption and a 10.5% reduction in cooling energy demand, corresponding to a saving of approximately 30,879 kWh per year. These findings demonstrate that incorporating occupant feedback into HVAC control strategies offers a practical, cost-free pathway to simultaneously improve comfort and reduce energy consumption in green office buildings. The study contributes empirical simulation evidence from an under-represented African context and strengthens the case for contextually grounded comfort standards in building energy policy.