Accurate measurement and monitoring of a computer room air conditioning unit's cooling production, distribution, and consumption is necessary to optimize effectiveness and efficiency and minimize redundancy. A mass air flow monitoring device comprises an array of sensor modules and a controller module with display, user interface, and I/O for third party connectivity. The device monitors temperature, pressure, water content, and quantity of airflow in a CRAC's supply air stream and return air stream and compares the two measurements to determine the amount of energy, or enthalpy, put into or taken out of the air. The result, displayed in watts, allows for the efficient control of production, distribution, and usage of supply air from the CRAC unit. Over or under provisioning can be quickly identified and corrected and, when used in conjunction with power consumption monitoring, a “watts of cooling for watts of power consumption” efficiency metric can be provided.