We are entering an age where saving energy is almost as convenient as wasting it. According to an EPA report issued in August 2007, the energy consumption of servers and data centers has doubled in the past five years and is expected to almost double again in the next five years. As energy costs become a greater percentage of the IT budget (an IDC report, IDC Worldwide Server Power and Cooling Expense 2006-2010 Forecast, September 2006, projects that by 2010, 70 cents of every IT dollar will be devoted to powering and cooling devices in the data center), energy efficient IT will become a major priority. However, recent studies emphasize that organizations are not yet set up to manage energy efficient IT at an operational level. 

Nevertheless, increasing efficiency is an imperative as most large enterprise IT organizations spend approximately 5 percent of their total IT budgets on energy. This could rise by two to three times within five years, according to Gartner. Indeed, much has been written about the need to implement green initiatives in data centers—from virtualization to environmental controls—that can help organizations improve efficiency, decrease energy costs, and, of course, reduce their carbon imprint on the environment. One of the major challenges in going green is that there are significant barriers to a comprehensive "greening" of the data center and/or enterprise network (costs of replacing older equipment, disruption to business processes, etc.).

However, organizations can put themselves on the path toward energy efficiency with minimum disruption in business practices (not to mention cost-effectively) by improving cabling and cable management, as the density in racks and cabinets require additional energy for proper cooling. In fact, cooling amounts to 50 percent of the power required to operate a data center.

No official regulations or policies exist today to define or govern the “greenness” of a data center. It is up to individual organizations to define operationally what a “green” data center means to them. There has been some legislation focused on promoting energy efficiency with regard to computer servers. House of Representatives Bill 5646 (To Study and Promote the Use of Energy Efficient Computer Servers in the United States), which passed in December of 2006, expresses Congressional sentiment that it is in the United States' best interest for purchasers of computer servers to give high priority to energy efficiency as a factor in determining best value and performance for purchases of servers.

Best Practices

The following outlines a best practices approach to energy efficient cable and equipment management in the data center:

• Use a hot-aisle/cold-aisle arrangement. In the cold-aisle/hot-aisle configuration, racks or cabinets are positioned to face each other, with front sides facing the cold aisle and back sides facing the hot aisle. It is important that the cold aisles remain segregated from the hot aisles. Efforts must be made so air from the two aisles does not mix. Ideally, the only airflow taking place between hot and cold aisles is through the equipment’s cooling fans. Allowing warmed air to return to the cold aisle raises the temperature of the equipment's intake air and minimizes the efficiencies of the equipment.
• Reduce cable congestion from under the raised floor to improve cold air movement. Underfloor cables should be routed to ensure cool air is delivered into the room. Cables should not block the perforated tiles in the cool aisle. Additionally, the underfloor plenum should not become filled enough to obstruct airflow.
• Improve airflow with innovative rack designs. In choosing an equipment rack, consider the ventilation configurations of the active equipment to be stored in the rack. If all the equipment uses front-to-back airflow, your task is easier and your range of cable management choices wider. If the equipment is side or bottom venting, make sure the rack can accommodate this scenario. Some racks combine baffles and perforations to direct airflow from side-ventilated equipment from the cold aisle to the hot aisle. The perforations allow ventilated air to be exhausted, while the baffles ensure the proper flow of air from cool aisle to hot aisle, even with side ventilation. In effect, the combination of baffles and perforations allow side-ventilated equipment to act like front to rear-ventilated equipment as far as cooling is concerned.
• Use smaller cables to reduce congestion. Newer reduced-diameter UTP and fiber optic cables improve airflow by taking up less space. With high-port-count equipment requiring large cable bundles, these reductions add up to significant space savings.
• Use blanking panels to prevent the unintended flow of air through the rack and the mixing of air from the hot and cold aisles. Blanking plates should be placed in unused equipment positions within the rack to maintain the hot-aisle/cold-aisle separation. This will allow more cold air to be directed to the equipment rather than be wastefully passed through empty areas. You can use blanking panels on the rear of the deep channel rack so the ambient air surrounding the switch is not heated by the air already in the hot aisle. The same approach also improves the cooling of servers and other front-to-back airflow equipment.
• Use occupancy sensor lighting. Overall, data centers accounted for 1.5 percent of the total electricity used in the states. (Lighting takes up around 22 percent, according to the Department of Energy.) According to the U.S. Environmental Protection Agency, energy savings from occupancy sensor lighting can range from 45 to 80 percent in storage areas. Ceiling sensors attached to the overhead tray can control lighting in larger areas of the data center. Digital time switches which are commonly used in equipment rooms, storage areas and closets are ideal for making sure task lighting mounted to individual racks or cabinets turns off when not in use. 

Case Study: A Manufacturer Goes Green

The right connectivity infrastructure is essential in creating a resilient, agile, and energy-efficient data center or storage area network (SAN). For one large manufacturing company, their chief objective in implementing a data center was to find ways to minimize energy consumption, as well as reduce the associated costs. Based on the best practices outlined, this organization implemented an advanced cable and equipment management system specifically designed for higher density applications.

The system featured a new cable management rack, which is designed to maximize the airflow of network equipment, whether it is side, bottom, or back vented. Innovative honeycomb side rails and baffles work together to manage intake and exhaust air, creating cold-aisle/hot-aisle air distribution for network equipment. The racks also use floor space efficiently—they have a 16.25" channel depth and can fit on a 2' x 2' floor tile.

In addition, the company installed energy efficient cabling—including reduced diameter copper cables and new compact high-fiber count cable technology. The latter being easy to install and terminate, and is 50 percent smaller than comparable fiber count ribbon cables. In short, the thinner the cables, the less congestion there is in the rack or cabinet, promoting more efficient airflow and cooling-and a decrease in energy use.

Going Green

As energy costs continue to escalate, IT organizations are faced with choices regarding how to increase the energy efficiency of their data centers and network infrastructures. These choices range from slow, steady improvements to quick, bold strokes. However, as this article illustrates, data centers can achieve significant—and immediate—gains in energy efficiency by implementing straightforward cable and equipment management best practices, with minimal or no disruption to network performance. This first step can help organizations lay a foundation for a comprehensive green strategy going forward.

Lars Larsen is a Product Manager, Physical Support with Ortronics/Legrand.