Performance of AC systems under future climates and heatwaves: From degradation to temperature regime optimization and dehumidification control

Rising outdoor temperatures and the increasing frequency of heatwaves raise pressing challenges to the resilience of building cooling systems, particularly in tropical regions where cooling demand is continuous, and dehumidification is essential. This study investigates the impact of future climate scenarios, including typical meteorological years and heatwave years provided by the International Energy Agency’s Annex 80, on the seasonal performance of conventional vapor-compression cooling systems: unitary systems, represented by split units. Numerical simulations were carried out using EnergyPlus to assess the Seasonal Coefficient of Performance (SCOP). Results indicate that split systems performance and optimal sizing strategies are sensitive to climate change, with SCOP degradation between 5% and 10% by the end of the century and up to 12% during severe heatwaves. In contrast, centralized chilled-water systems exhibit greater adaptability through temperature regime optimization. Raising the chilled-water supply temperature by several degrees reduces the refrigerant lift and distribution thermal losses, improving chiller SCOP by up to 5%. However, these benefits come at the expense of reduced dehumidification capacity, highlighting a fundamental balance between energy efficiency and hygrometric comfort. Overall, the results highlight the importance of considering future climate conditions when assessing air-conditioning performance and suggest that elevated chilled-water temperature regimes can improve system efficiency while remaining compatible with thermal and hygrometric comfort within a case-specific operating range. For the simulated chilled-water configuration, higher supply temperatures improved energy performance while maintaining acceptable indoor conditions up to system- and comfort-dependent limits.