Evaluating the energy efficiency potential of chilled water versus VRF air-conditioning system

Abstract

Air-conditioning systems play a vital role in maintaining indoor comfort, especially in commercial and large-scale residential buildings. However, there is insufficient research on identifying the most energy-efficient solutions for diverse applications. This study bridges the gap by evaluating the energy efficiency potential of chilled water systems compared to water-cooled and air-cooled Variable Refrigerant Flow (VRF) systems, addressing critical considerations for their adoption in different settings. The research employs a dual-method approach, combining actual measured data with simulated data to evaluate system performance under various climatic and operational conditions. Key performance indicators such as energy consumption, cooling capacity, and system efficiency were analysed to determine the comparative advantages of each system. This methodology ensures a balanced assessment of real-world operation and theoretical predictions, providing a robust framework for decision-making. The findings indicate that water-cooled VRF systems, specifically those utilizing seawater, (due to having heat capacity higher than that of freshwater) are the most energy-efficient option, owing to their high thermal conductivity and natural cooling potential. However, their efficiency is contingent on specific conditions, including proximity to coastal areas and access to seawater for heat exchange. Air-cooled VRF systems rank as the second most efficient option, offering greater flexibility and lower infrastructure requirements, making them suitable for medium-scale buildings. In contrast, chilled water systems are the least efficient in terms of energy consumption but remain a preferred choice for large-scale buildings due to their ability to handle substantial cooling loads and centralized operations. The study underscores the importance of contextual factors such as building size, location, and operational requirements in selecting the optimal air-conditioning system through the implementation of operational monitoring and control. While VRF systems excel in adaptability and energy savings in smaller setups, chilled water systems continue to dominate in large-scale applications despite their higher energy consumption. This research provides actionable insights for engineers and designers to guide sustainable and energy-efficient air-conditioning solutions, contributing to reduced operational costs and environmental impacts in the building sector.