For facility managers looking to save energy in data center operations, the first target is the HVAC system.
Several strategies are worth considering as data centers are being designed. One is the use of airside economizers. This free cooling is available in many parts of the country for much of the year. When outside temperatures are appropriate — typically, below 55 degrees — the hot return air is exhausted and cool outside air is brought in. The air conditioning units don’t run, saving a significant amount of energy. Because data centers often require cooling through the night, they can take advantage of the lower nighttime temperatures. Another way to reduce HVAC costs is by specifying more efficient equipment.
Today’s chillers, for example, can be equipped with variable frequency drives to improve efficiency, while cooling towers with drift eliminators can significantly reduce water consumption. Chillers in data centers have often been oversized because of concerns about reliability and to allow for future growth. A variable, primary-only pumping configuration can enable a chiller to operate closer to its design “delta-T” — that is, the difference between supply and return temperature — both when it is fully loaded and when it is partly loaded. This pumping configuration also reduces chilled water bypass, reduces initial cost (since fewer pumps are required), and increases reliability (since there are not as many single points of failure). Improving airflow is another opportunity for facility managers who want to cut HVAC operating costs. Computational fluid dynamics (CFD) is a useful tool for achieving that goal. A CFD model enables a facility manager to analyze different design options because it shows data center air flows, pressures, and temperatures under different operating situations.
Click here to learn more about airside economizers and other strategies to reduce the energy used in data center cooling.