A New Tool for Evaluating and Designing the Thermal Environment in Telecom Central Offices

Telecom central offices need a metric for evaluating and designing the thermal environment to ensure effective equipment cooling without excessive energy usage. This paper presents such a metric: the rack cooling index (RCI). Although the equipment intake temperatures provide a picture of the environment, there is no yardstick for interpreting the data. The RCI has the capacity to change this situation; the index is a metric of compliance with (industry) temperature specifications, where 100% means that the equipment is ideally cooled. More importantly, it allows standardized and unbiased comparisons between different thermal environments. Ultimately, the cost of controlling the thermal conditions needs to be understood. Therefore, a cost metric for cooling the equipment room is reviewed. By incorporating the RCI and cost functions in the design process, it can be shown that a design not only improves the environment but also saves energy. The RCI is currently used to evaluate various cooling solutions as well as develop telecom standards for optimal thermal design of equipment rooms. Other applications include real-time monitoring and design specifications. It has the capacity to support non-technical decision makers since interpreting the index does not require an in-depth understanding of its definition. A design with an RCI of 95% is obviously better than one with 85%