Precooling Ventilation Air for Hospital Operating Rooms and the Affects on Terminal Box Reheat

This study evaluates the impact of climate on the energy performance of two HVAC system configurations—AL1, a conventional air handling system, and AL2, which incorporates a pre-cooling coil and discharge air temperature (DAT) reset strategy. Using EnergyPlus simulations, each system was modeled across multiple U.S. cities representing a wide range of climate zones. Results show that AL2 significantly reduces plant energy consumption, with an average energy savings of 66.61\% compared to AL1. These savings were nearly evenly split between reductions in heating and cooling demands. A weather normalization analysis using cooling and heating degree days (CDD65 and HDD65) revealed a moderate correlation between climate severity and energy savings. Specifically, AL2 showed a slight positive correlation with CDD65 and a stronger negative correlation with HDD65, suggesting improved performance in colder climates. However, a substantial portion of the variation in energy savings remains unexplained by climate alone. Additionally, the implementation of AL2 was found to increase the system’s sensitivity to local weather conditions, especially in cooling performance. These findings underscore the potential of control-based HVAC strategies to reduce energy use across diverse climates while highlighting the importance of climate-specific system design. The study provides valuable insights for optimizing HVAC system performance in healthcare and similarly demanding indoor environments.