Abstract: A data center thermal control system includes a local cooler configured to cool a local coolant used for cooling electronic hardware, an outer heat exchanger configured to exchange heat from fluid to outside air, and a fluid circulation system configured to convey heat from the local cooler to the outer heat exchanger by circulating at least one fluid cooling medium, the fluid circulation system including a cold portion directed to the air cooler. The thermal control system also includes one or more processors and a non-transitory computer-readable medium storing instructions that, when executed by the one or more processors, would cause the one or more processors to govern the outer heat exchanger to cool fluid in the cold portion to a first target temperature during a hot season, and cool fluid in the cold portion to a lower target temperature during a cold season.