Cool design data center

A cooling system for a data hall comprising:

• an enclosed hot aisle accommodating a hot air stream, the hot aisle comprising an exhaust opening formed at one end thereof through which the hot air stream exits the hot aisle;
• a cold aisle accommodating a cold airstream, the cold aisle being physically segregated from the hot air aisle, the cold aisle directly connected to a supply plenum, said supply plenum selectively receiving ambient air from an outdoor environment based on climatic outdoor conditions;
• a hot aisle plenum in direct physical contact with the exhaust of the hot aisle and segregated from the supply plenum, wherein complete elimination of hot and cold air counterflow is achieved between the hot air exiting the exhaust of hot aisle and cold air in the cold aisle and the supply plenum;
• a data hall variable air volume (VAV) system;
• and
• wherein said hot aisle plenum further comprises both an exhaust to said outdoor environment and a return to a conditioning system of said supply plenum such that said hot airstream can be selectively exhausted outdoors and provided to said conditioning system based on said climatic outdoor conditions;
• in which a control envelope defines a temperature, humidity and enthalpy for air provided by said supply plenum, wherein said air conditioning system selectively conditions air from the outdoor environment, air from the hot airstream or a mixture thereof based on whether said climatic outdoor conditions are within said control envelope.