10 must be built on a new site referring to fig8 a the hybrid loop control method 800 for cooling a module 200 is described with the help of a flowchart this method 800 applies independently for each of the two cooling subsystems in the module 200 the method starts at 801 by initially fully opening the intake and exhaust dampers 276 and 278 and fully closing the mixing dampers 275 the chilled water valve is also initially closed so that no water is flowing through the coils 222 finally the humidifiers 224 are also initially shutoff then the method 800 enters a loop where outside air conditions are first evaluated if temperature or humidity are out of limits u201c yes u201d branch at 802 then the system may no longer operate in hybrid loop and is automatically switched to closed loop operation see 900 of fig9 indeed when the outside temperature nears the set point temperature for the cold air plenum the system can no longer operate in hybrid loop in any practical way so it reverts to closed loop operations the decision can be implemented using either the outside dry bulb temperature or the more precise air enthalpy if the outside conditions are.