Comparative Analysis of Low- and High-Temperature Chilled Water Systems in Terms of Energy Performance in Office Buildings

This study examines the impact of chilled water supply parameters on the energy efficiency of an office building’s HVAC system located in a temperate European climate. Two cooling system variants were analyzed: (1) a traditional low-temperature system using fan-coil units and (2) a high-temperature system with chilled beams for sensible cooling. In the latter, moisture removal is performed entirely by the air handling unit, where outdoor air is dehumidified before being supplied to the space. Hourly simulations were carried out for the summer period using typical meteorological year data. Detailed heat gain calculations included transmission, occupancy, equipment, lighting, and solar radiation. Based on the cooling loads, chilled water production and distribution systems were selected, and their electricity consumption was assessed. The total energy use of chillers, ventilation units, circulation pumps, and auxiliary equipment was compared for both systems. The findings highlight the energy-saving potential of high-temperature chilled water systems, especially when integrated with centralized ventilation capable of latent load control. Additionally, results show that increasing the chilled water supply temperature significantly enhances the Energy Efficiency Ratio (EER) of chillers.