Most existing data centers use underfloor air distribution. And of those data centers that use underfloor air distribution, most use uncontained hot and cold aisles. Cooling capacity to the raised floor plenum for these data centers is typically provided with constant volume computer room air conditioning (CRAC) units for most older facilities; newer data centers typically use variable volume CRAC units. Various strategies have been devised to utilize either underfloor pressure or cold aisle temperature as the controlled variable to determine either the amount of CRAC units to operate or the speed of the CRAC unit fans. Often, these strategies are implemented through the Building Automation System. Unfortunately, more often than not, these strategies don't work effectively because the user of the facility is not adequately prepared to understand that despite the fact that an automation system has been provided for the data hall air flow, the placement and the quantity of perforated tiles is not automated.
This paper will address how to select appropriate perforated tiles for various data center densities. In addition, it will provide guidelines for how to manage the quantity and placement of the tiles. These guidelines will assist in optimizing the important operational and maintenance issues for cooling the data center – delivering cold air to the servers, minimizing bypass and recirculation air flows, and adjusting the quantity and placement of the tiles as the facility loads change overtime.