A data center module is a data center that can be prefabricated using generally standardized off-the-shelf components, and quickly assembled on a collocation site where a shared central facility is provided. The data center module is typically configured to be deployed with other identical data center modules around the central facility both in side-to-side and/or in back-to-back juxtapositions, typically without the need for interleaving space between adjacent modules in order to maximize real estate use. Each data center module typically comprises harden party walls, several floors for accommodating all the necessary electrical and cooling subsystems and for accommodating all the computing machinery (e.g. servers). Though all the data center modules share similar physical configuration, each data center module can be independently customized and operated to accommodate different needs. Each data center module also incorporates a highly efficient hybrid cooling system that can benefit from both air-side and water-side economizers.