There are numerous factors to consider when it comes to perforated tiles in data centres, and depending on who you speak with, you will receive varying responses. A data center's server floor is often elevated, with cold air pumped beneath the floor by massive CRAH (Computer Room Air Handlers) or CRAC units (Computer Room Air Conditioners).
This chilled air passes through the perforated tiles and into the data centre, cooling the heat generated by the servers and other data centre electrical equipment. Because the data centre load is a sensible load, as data centres do not contain a significant amount of humidity from external sources, the cooling equipment simply needs to be capable of cooling the sensible load, with no concern about latent loads.
Consider the quantity of CFMs required for airflow when using perforated tiles. The temperature of the air entering from the CRAH or CRAC units is normally consistent. Underfloor pressure control is typically utilised to achieve a specified quantity of airflow, and as a general guideline, a data centre requires 150 CFM of airflow for every 1 kW of server load.
Thermal imaging is one method, but by taking temperature readings and plotting them across the data centre, one can assess whether or not this rule fits the requirements for a particular data centre and floor layout. Additionally, a CFD (Computational Fluid Dynamics) analysis can be performed using specialised software (see video below) to determine the output of certain equipment and the optimal placement of perforated floor tiles in the data centre.
Through short trials (and my limited knowledge with data centres), I've determined that the position of the perforated tiles may be adjusted to reach the optimal temperatures in a cold aisle/hot aisle data centre. Perforated tiles installed too close to CRAC Units can obstruct airflow.