Air filter effects on data center supply fan power

Driven by need to reduce energy use, many new data centers are built with air-side economizers. This method of bringing in outside air as the primary cooling resource greatly reduces overall facility power by eliminating need for the compressors and pumps required by chilled water and refrigerant based cooling systems. However, system fans are still necessary to supply and move large amounts of air through the facility. The operating power of fans is dependent on the static pressure which must be overcome to move air. The static pressure of a data center is generally fixed for a given configuration, with the exception of air filters which become clogged over time. In this work, airflow versus pressure drop curves of filters removed after eight and a half months of service in a large data center operating an air-side economizer are experimentally characterized. Comparisons of this data against clean filters provides insight into the change in pressure drop of both low-efficiency pleated pre-filters and high-efficiency cartridge final filters as they become dirty. Incorporating these system resistance curves into the power curve of the data center supply fans indicates only minimal increase in energy use resulting from dust and particle collection of the filters.