Climate zones for the application of water-side economizer in a data center cooling system

•Evaluate water-side economizers for energy savings and water in different regions.•Compare the performance of water-side economizers at two chilled water temperatures.•A new indicator, water to energy saving ratio is proposed.•Water-side economizer applicability in 34 Chinese cities is divided into 4 zones. Water-side economizers have been widely adopted in response to the growing energy consumption in data centers. Although many studies have recognized the energy-saving effects of water-side economizers under different climate conditions, their water utilization is still unclear. This study combines energy savings and water consumption to assess the applicability of water-side economizers in 34 cities in China under two sets of chilled water supply and return water temperatures. The energy savings when the supply and return water temperature is 21/27 °C are 3.17 times higher than when it is 12/18 °C. Nine cities can reduce water consumption while pursuing energy savings. To further quantify the applicability of water-side economizers, this work introduces a new indicator, water to energy saving ratio, and utilizes K-means clustering to conduct zoning studies on different cities. The results show that the applicability of water-side economizers in different regions can be divided into four zones. In Zone I, the applicability of water-side economizers is the lowest, and it is recommended that they be combined with high-efficiency heat transfer technologies. Zone II comprises 12 cities, with moderate applicability of water-side economizers. In Zone III, there is a need to balance the relationship between water and energy. Zone IV has the lowest energy and water consumption, with an average of 23% water resource savings compared to Zone I. However, attention should be paid to preventing the freezing of cooling towers in winter.