PUE and CCF: Why you need to measure both7 min read

by | Aug 27, 2013 | Blog

Power Usage Effectiveness (PUE) is a widely used metric for evaluating the overall efficiency of data center infrastructure. In fact, PUE data reveals that the cooling infrastructure is the single largest consumer of data center power (typically around half), and therefore, the largest contributor to a high PUE value. So it seems logical that improving cooling infrastructure efficiency will obviously translate into the largest reduction of a site’s PUE value. However, PUE can’t possibly tell you the whole story.

Identifying opportunity for improvement starts with examining your cooling capacity. Unfortunately, the average computer room today has rated cooling capacity that is nearly four times the IT heat load. Some sites we reviewed had even more. We are finding that businesses end up pouring millions of dollars into building new data centers or acquiring new data center space long before they actually need to, simply because the cooling capacity of their computer rooms is so misunderstood.

Enter, the CCF (Cooling Capacity Factor), which is the ratio of total running rated cooling capacity to 110% of the critical load. CCF is a simple and practical metric for determining and understanding current inefficiencies in your current cooling infrastructure, as well as identifying opportunities for improvement. Knowing your CCF allows you to fully understand your current utilization of cooling capacity, and what potential you have to increase efficiency. Fortunately, improvements to efficiency usually come through improving AFM (airflow management), the most cost-effective way to reduce power consumption. This level of insight is something that PUE alone can’t reveal!

When you can identify with certainty that your cooling capacity is excessive, then potentially huge OpEx savings are possible. Those savings can come in the form of reduced energy costs, or in the delay of capital expenditures since your excess cooling capacity now allows you to add more servers without adding more cooling units. Regardless of your end business objective, CCF helps you understand your cooling more than just relying on PUE. Knowing your CCF allows you to make an informed decision about where to most effectively invest your efforts next.

Learn more about discovering your CCF with our free helpful tools:

CCF White Paper

CCF Online Calculator

Lars Strong

Lars Strong

Senior Engineer


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