A data center cooling system, comprising: a plurality of server racks aligned within a row in a human-occupiable workspace of a data center , the server racks supporting a plurality of heat-generating computing devices; a warm air aisle positioned adjacent the server racks opposite the human-occupiable workspace and comprising a warm air inlet adjacent to a back side of the row of server racks and a warm air outlet in fluid communication with a warm air plenum; a plurality of cooling modules serially connected in a row, each one of the plurality of cooling modules comprising at least one fan (201-203) and a cooling coil, the cooling modules positioned to circulate a cooling airflow from the human-occupiable workspace , through the server racks , and to the warm air aisle ; a single controller communicably coupled to each of the plurality of cooling modules in the row and operable to perform operations comprising: controlling the plurality of fans (201-203) in the plurality of cooling modules to operate at a specified fan speed; and controlling a plurality of valves fluidly coupled to the plurality of cooling coils in the plurality of cooling modules to modulate to a specified valve position; and a power source for powering the plurality of cooling modules , wherein each cooling module in the plurality of cooling modules includes a power input interface configured for coupling to the power source and a power output interface coupled to a bus for providing power to the single controller . a plurality of server racks aligned within a row in a human-occupiable workspace of a data center , the server racks supporting a plurality of heat-generating computing devices; a warm air aisle positioned adjacent the server racks opposite the human-occupiable workspace and comprising a warm air inlet adjacent to a back side of the row of server racks and a warm air outlet in fluid communication with a warm air plenum; a plurality of cooling modules serially connected in a row, each one of the plurality of cooling modules comprising at least one fan (201-203) and a cooling coil, the cooling modules positioned to circulate a cooling airflow from the human-occupiable workspace , through the server racks , and to the warm air aisle ; a single controller communicably coupled to each of the plurality of cooling modules in the row and operable to perform operations comprising: controlling the plurality of fans (201-203) in the plurality of cooling modules to operate at a specified fan speed; and controlling a plurality of valves fluidly coupled to the plurality of cooling coils in the plurality of cooling modules to modulate to a specified valve position; and controlling the plurality of fans (201-203) in the plurality of cooling modules to operate at a specified fan speed; and controlling a plurality of valves fluidly coupled to the plurality of cooling coils in the plurality of cooling modules to modulate to a specified valve position; and a power source for powering the plurality of cooling modules , wherein each cooling module in the plurality of cooling modules includes a power input interface configured for coupling to the power source and a power output interface coupled to a bus for providing power to the single controller . <EOS>