Energy and Water-Saving Strategies for Data Center Cooling in Tropical Climates: A Literature Review with a Bangkok Case Example

Abstract Data centers in tropical climates face distinct cooling challenges. High ambient temperature and humidity limit free-cooling opportunities, which often raises Power Usage Effectiveness (PUE) and Water Usage Effectiveness (WUE) above the levels seen in temperate regions. This paper reviews existing studies on energy- and water-saving strategies for data center cooling, with emphasis on hot-humid climates, and identifies research gaps relevant to Thailand. The reviewed strategies are zone and supply-air setpoint, chilled-water temperature, free cooling and economizers, cooling-tower water management, and system design factors such as redundancy and rack density. The literature shows that savings reported in temperate climates, including up to 68% cooling-energy savings from economizers, do not transfer to hot-humid zones, where a water-side economizer returned 0% savings and an indirect evaporative cooler 7.5%. Most studies report PUE alone, and none of the studies compared here reports a water metric next to it. A short case example, based on a preliminary EnergyPlus simulation of a 2 MW data center in Bangkok, illustrates these findings: no free-cooling hours, a 20% water saving from raising cooling-tower cycles of concentration from 3 to 6, and a combined scenario that reduced PUE from 1.39 to 1.38 and WUE from 3.02 to 2.40 L/kWh. The review concludes that operational measures alone are unlikely to meet common PUE and WUE targets in Thailand, and that evaporative cooling, equipment-level upgrades and studies that report water alongside energy deserve further attention.