Cooling a data center

1. 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 each comprising at least one fan and at least one cooling coil mounted together in a housing, the cooling modules positioned to circulate a cooling airflow from the human-occupiable workspace, through the server racks, and to the warm air aisle; and

a single controller electrically and communicably coupled to each of the plurality of cooling modules in a serial arrangement and operable to perform operations comprising:

controlling the plurality of fans 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,

wherein the serial arrangement of the single controller comprises the single controller being electrically coupled to each of the plurality of cooling modules by a direct current (DC) control power bus to receive power from a first cooling unit through the DC control power bus, independently of a loss of power to the remaining cooling units of the plurality of cooling units.

2. The data center cooling system of claim 1 , further comprising a plurality of temperature sensors positioned on the plurality of cooling modules.

3. The data center cooling system of claim 2 , wherein the plurality of temperature sensors are configured to determine a cooling coil entering air temperature and a cooling coil leaving air temperature.

4. The data center cooling system of claim 2 , wherein the plurality of temperature sensors are configured to determine a cooling coil entering cooling liquid temperature and a cooling coil leaving cooling liquid temperature.

5. The data center cooling system of claim 1 , wherein controlling the plurality of fans in the plurality of cooling modules includes operating at the specified fan speed based, at least in part, on a temperature of a cooling module in the plurality of cooling modules.

6. The data center cooling system of claim 2 , wherein controlling one of the plurality of fans and the plurality of valves is based on a differential pressure calculated across the warm air aisle.

7. The data center cooling system of claim 2 , further comprising a plurality of filler panels configured to isolate the human occupiable workspace from the warm air aisle.

8. The data center cooling system of claim 7 , wherein the warm air aisle is inside a heat containment structure at least partially defined by the plurality of filler panels.

9. The data center cooling system of claim 8 , further comprising a plurality of temperature sensors coupled to the heat containment structure.

10. The data center cooling system of claim 1 , wherein controlling the plurality of fans includes individually controlling each fan in the plurality of fans to a specified rotational speed.

11. The data center cooling system of claim 10 , wherein controlling the plurality of fans includes actuating all the fans in the plurality of fans together at the same speed.

12. The data center cooling system of claim 2 , further comprising a network interface communicably coupled to the controller for remotely configuring the controller.

13. The data center cooling system of claim 12 , wherein each cooling module in the plurality of cooling modules includes a power input interface configured for coupling to a power source and a power output interface coupled to the controller.

14. The data center cooling system of claim 12 , wherein the cooling module includes a transformer circuit configured to convert AC current to DC current.

15. The data center cooling system of claim 14 , wherein the transformer is configured to reduce the voltage of the AC current.

16. The data center cooling system of claim 2 , wherein the cooling conduits of the plurality of cooling modules are serially fluidly coupled.

17. The data center cooling system of claim 1 , wherein the single controller is configured execute at least two control loops that comprise a temperature control loop and a pressure control loop, the temperature control loop configured to control an opening percentage of a respective valve of each of the plurality of cooling modules, and the pressure control loop configured to control a speed of respective one or more fans of each of the plurality of cooling modules.