Data center is a specific building space accommodating and managing data processing equipments which rely on the thermal environment for continuous operation. Based on the review of current research on evaluating thermal environment in data center

this paper defines a dimensionless index to evaluate the effect of air mixing on the equipment and characterize thermal security in local space of data center. This mixing index emphasizes on evaluation of thermal security (or failure potential) of data center environment

which is different from current evaluating system based on average inlet air temperature of data processing equipment. Through the distribution of such a mixing index

not only the distributed characteristics of data center air flow can be understood

places of potential hot spots or overheated space can be located and improved accordingly. Thermal environment of data centers with different building area

equipment layout and air flow pattern can be directly compared using heat weighted mixing index which also helps to guide the thermal design of new data centers and thermal optimization of existing data centers.