4  FM quick reads on Data centers

1. 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.

2.  Find Allies to Win Funding for Facility Projects

Today's tip has to do with winning top management approval for facility projects.

Gaining funding for a project is a challenge all managers face. Top management has to weigh projects from across the organization, then allocate financial support to the ones that will ultimately provide the most benefit to the entire organization.

One way to improve the case for a facility project is to show that it will provide direct benefits to other departments or business units. For example, if the facility manager wants to upgrade aging parking lot lights, energy savings may only be one benefit. By talking to other managers or the human resources department, the facility manager may be able to show that the dim, yellow light from old fixtures makes employees who work late nervous as they walk out to their cars.

Similarly, it may seem obvious to the facility manager that an unreliable generator in a hospital or a Tier 1 data center needs to be replaced. But if the proposal to replace the generator has the support of the head of medicine or of IT, it stands a much better chance of being approved.

There are plenty of other examples, ranging from new HVAC equipment that will save energy and reduce maintenance costs while addressing employee complaints about comfort to a new access control system that may reduce liability while making employees feel safer. The key is to think broadly about the benefits of a facility project.

Taking that approach provides the facility manager with an ally in the battle for funds. It also shows top executives that the facility manager is taking a company-wide perspective, rather than simply looking at the needs of the facility department.

3.  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.

4.  Avoid Rush Jobs By Building Bridges to Other Departments

In many organizations, facility executives are the last to know about important changes that will require changes to the physical environment. In some cases, those changes involve equipment, as when new servers for the data center show up with no warning on the loading dock. In other cases, the changes involve people for example, the addition of new staff whose workstations will have to be set up. The result is a rush job and a lot of hassle for the facility department. Grumbling about the problem after the fact won't help prevent it from happening again. A better route is to let the other department know what's in it for them to notify the facility department of impending changes. Advance word might enable servers to be up sooner or might spare the other department the stress of a last-minute rush to get workstations set up. An even better strategy is to develop a good relationship with other departments so that you can get the information you need in advance. Ideally, the relationship will evolve to include regular two-way communication about matters of importance to the other department. But in the beginning, it may be a matter of periodically checking in with the other departments to find out what they have coming.


Data centers , chillers , energy efficiency , VFDs , pumping , delta-T

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