4  FM quick reads on Data centers

1. FM-IT Partnership Can Increase Data Center Energy Efficiency

Today's tip: Partner with IT to boost data center energy efficiency.

Data centers are the equivalent of a 1967 Corvette. Most vintage Corvette owners probably know that their cars only get about 10 miles per gallon. Odds are they don't care too much. They just want to go fast.

Historically, most IT managers have looked at data centers about the same way. They have not cared about how much energy their servers used. They just wanted their data centers to run reliably and securely — and be as fast as possible.

IT's desire for data centers to be reliable and secure has not changed. But the IT attitude toward energy use is changing. The reason is simple: money. Data centers are energy hogs - so much so that top management is taking notice and putting pressure on IT to join FM to help find ways to cut costs.

There are plenty of ways that facility management and the IT department can work together. One example is to adopt the current ASHRAE guidelines for data center temperatures. ASHRAE's Technical Committee 9.9 has raised the recommended data center temperatures, but not all data centers have adopted the new guidelines. One obstacle is that IT departments may be concerned that higher temperatures will threaten server reliability.

Another opportunity to work with IT is to get the IT department to specify energy efficient servers. These may cost somewhat more, but the energy savings can justify the extra cost.

In both cases, facility management has an opportunity to educate the IT department about the opportunties to save energy. For example, IT may not realize that unnecessarily cold temperatures have a ripple effect on data center costs. Keeping data centers colder than need be requires extra cooling capacity. That increases the construction cost of a data center. And running that extra capacity adds to the data center energy cost.

Chiller System Design Can Improve Data Center Energy Efficiency

Today's tip: Pay attention to chiller system design to improve data center energy efficiency.

The early data center design phase is the time to address chiller system configurations, pumping system topologies, chilled water loop supply temperatures and selection of energy efficient equipment.

Today's chillers can be selected for far lower kW/ton electrical use than in the past. Equipping the chiller with a VFD and condenser water reset is usually the most efficient option, because the VFD will adjust the chiller performance as the compressor load and condenser water supply temperature vary. Newer, highly efficient cooling towers with drift eliminators can be selected to reduce water use by as much as 40 to 50 percent.

Chiller systems for data centers have historically been oversized, resulting in less efficient operation until the data center is completely populated and full design loads are realized. Chillers are designed to operate at a specific difference between supply and return temperature or "delta-T." An efficient and properly-designed system will allow the chillers to operate closer to the design delta-T over the entire range of expected load conditions. A number of design strategies can contribute to achieving this goal, including pumping system configuration and reducing system bypasses.

Variable, primary-only pumping eliminates unnecessary chilled water bypass and allows the chiller to operate nearer to its optimized delta-T both during full- and part-load conditions. A traditional chiller design, in which a constant flow through the chiller is maintained, results in the delta-T staying proportional to the load. In a variable primary-only flow pumping system, the flow tends to stay proportional to the load while the delta-T stays closer to the optimized condition for the selected chiller. Also, a variable primary system requires fewer chilled water pumps (which lowers first cost), has fewer single points of failure (which makes it more reliable) and simplifies the chiller plant installation and controls.

Using Water to Cool a Data Center

If your data center is consistently running too hot, or if you're dealing with extra density from blade servers, you may not have much choice than to consider an in row cooling solution that uses water. Putting water in a data center goes against everything data center operators have been taught for years. But with skyrocketing heat loads, it's going to become more common.

One thing to keep in mind is the connections. Connections can range from a simple clear rubber tubing with hose clamps to threaded brass connections.

Also keep in mind how connections are routed under the floor. What if a fitting cracks or a pipe leaks? Are the shutoff valves easy to locate? Are the workers trained so they can quickly and easily shut a valve off? Are seal-tight electrical conduits used? If not, power connections won't be protected from leaks. And if a pipe does leak, can water easily flow to a drain, or will it be restrained by a mass of tubing and conduits, which could cause flooding.

For more on cooling, see the FaciliesNet Data Centers topic page.


Data centers , IT , facility management , energy efficiency , servers , cooling , ASHRAE

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