The benefits to optimizing airflow in your data center are numerous, with the most attention-getting reason being up to a 30 percent energy savings. But achieving this type of savings is much more involved than simply turning off a CRAC unit. The underlying issues must be addressed and resolved before mechanical load can be reduced and savings realized.
When assessing a client’s critical environments, I often find the issue isn’t one of capacity or volume of air, it’s one of distribution and delivery of air. In its simplest form, it’s a matter of being able to get the right amount of cooling resource where it’s needed when it’s needed, and only that amount, and not being able to remove/stop exhaust heat from mixing. Inversely, returning the hot exhaust air directly back to the air handlers is just as important. Managing distribution, delivery, return, and eliminating mixing can yield significant efficiency gains. Efficiency gains can be realized as direct savings, increased manageable load, increased redundancy, and/or capital expenditure avoidance.
The good news is that there are ways to achieve these efficiency gains without breaking the bank – simple best practices that yield real results.
Plug the Holes
Cable cut outs, holes, and bad tile fitment in the raised floor leak valuable cool air and drop the sub-floor pressure. Use brushed grommets, plenum rated foam inserts, or other similar products. Do not use cardboard. Cardboard emits particles that can harm electronic equipment. The loss of CFM through cutouts in a raised floor in an average size U.S. data center results in more than $50,000 annually of wasted energy.
When it comes to a data center’s airflow, recycling is not a good thing. Large open spaces in the cabinets allow for hot exhaust to float back to the front of the cabinet and cycle through the racked equipment again. This scenario produces an elevated server exhaust temperature. As cold air drifts past the intended server, it intermingles with the exhaust and decreases the effectiveness of the cooling system. Blanking panels fill in these open cabinet spaces and prevents this scenario.
The numbers are very compelling when it comes to using blanking panels. According to the Environmental Protection Agency, adding a single 12” blanking panel to the middle of a server rack can yield one to two percent energy savings.
Turn It Up
The temperature, that is. Approximately three-fourths of all data centers set their temperatures below 75°F degrees, when the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) has a recommended maximum of 80.6°F and allowable maximum of 95°F. Just a few degrees can make a difference. In fact, with each degree of increase, power bills can reflect a two-percent increase in savings!
Clean Up Cabling
If you can’t reach in the back of your cabinet and touch any one of the racked servers then you have cable management issues. Server manufacturers offer an array of articulating cable management arms but these same manufacturers also publish white papers stating the negative effects this form of cable management has on a server enclosure. Keep these tips in mind when creating a structured cabling system:
- Refrain from utilizing the server manufacturer’s articulating cable management arms or install them only for servers that require a high degree of access.
- Size the cables to proper lengths.
- Employ vertical cable management that the cables to the cabinet sides.
While the suggestions listed above can improve efficiencies and save money, there’s much more out there to take advantage of. While these next steps would require the help of an airflow expert, ROI could be achieved in a very short time and efficiencies sustained year-after-year through integrated monitoring. These measures include:
- Hot and/or cold aisle containment
- Smart rack, cabinet, CRAC placement
- Installation of subfloors with overhead air delivery
- Installation of fan-assisted floor tiles
- Incorporation of green strategies such as Fresh Air, Variable Frequency Drive, and decommissioning excess servers.
By no means is this list of airflow optimization improvements comprehensive. What improvements has your facility made? I’d like to hear about new ideas as well as results you’ve achieved by implementing any of the suggestions above.
About the Author
Rob Huttemann is the Senior Vice President of Operations for Critical Environments Group. He has more than 30 years of industry experience and familiarity with data center and supporting infrastructure management, with specific focus on power, space and storage, cooling, and overall best practices. CEG is a national provider of data center and critical environment infrastructure optimization solutions. For more information, please visit www.criticaleg.com.