By: Drew Hamilton
Integrated Design Group hosted a roundtable discussion on how to improve an existing data center. As a member of the mechanical engineering department and with experience on several legacy data center projects, I was asked to prepare some tips on how data center operators can perform a quick tune-up for their critical facility. Here is my top 7 list:
1. Seal raised floor. This includes the area around all of the equipment (CRAHs, PDUs, etc.) It is a simple detail but we find that 2″ to 3″ gaps are often ignored. Every inch counts; seal it up!
2. Separate supply (cold) and return (hot) air streams. Prior to efficiency, the focus for data center operators was reliability. Many data centers built around 2006 and earlier do not have efficient hot/cold aise arrangements. These days, nearly every design incorporates a hot/cold aisle layout; physical separation of the aisles is becoming common practice. Both hot aisle and cold aisle containment can ensure that the supply and return air streams never mix, thus preventing waste of cooling energy.
** Steps 1 and 2 set you up for steps 3 and 4 where you can start to see savings in energy and money!**
3. Raise supply air temperature. Fifty five degrees Fahrenheit is the traditional temperature for cooling from the floor of a data center, but if you separate the hot and cold aisles, you can raise temperatures to about 75˚ F or even higher. Integrated Design Group saved one client $100,000 in annual electric bills by making this simple change.
4. Raise chilled water temperatures. This is where Integrated Design Group sees the biggest savings for most data center clients and it goes hand-in-hand with raising your air temperatures. When you are supplying warmer air to the data center, the chillers are no longer required to make 45˚ F water year round. Even raising your chilled water temperature by a few degrees can provide savings.
5. Turn off redundant CRAH units if not using VFDs. This step costs the data center owner nothing! VFDs are a common addition to almost any fan these days. However, if you have older equipment and no budget to upgrade to VFDs, turning off some of the redundant CRAHs can produce energy savings. But, be careful; your system was designed with redundancy for a reason so if you turn off all of the redundant CRAHs, you could be in trouble in the event of a failure. Data center operators should also look into incentives that utility companies may provide for adding VFDs to CRAHs.
6. Run redundant cooling towers. Another zero cost item for the data center owner! It’s an old landlord’s myth that you can save money by shutting down equipment. In actuality, running redundant cooling towers can save energy in multiple ways. One savings method is through the VFD fans on your tower. It can actually be cheaper to operate four towers at 75% as oppposed to three towers at 100%. Another opportunity for savings is to provide colder condenser water to your water-cooled chillers. While this may require your cooling towers to work a little harder, it allows your chillers (by far, the largest energy consumer) to run more efficiently.
7. Preventative maintenance. We all (should) brush, floss and rinse to avoid a bad dental visit. The same mentality applies to data centers. Data center operators should run preventative maintenance, such as cleaning chiller tubes to maximize heat transfer. Integrated Design Group recommends calibrating instruments once a year; an incorrect temperature reading can be costly. We also advise data center managers to keep filters clean and to replace them often. This will reduce static pressure on the fans. And, don’t forget about water treatment. Keeping your water clean allows for better heat transfer.