Information technology (IT) is becoming increasingly pervasive throughout society as more data is digitally processed, stored, and transferred. The infrastructure that supports IT activity is growing accordingly, and data center energy demands haveincreased by nearly a factor of four over the past decade. Data centers house IT equipment and require significantly more energy to operate per unit floor area thanconventional buildings. The economic and environmental ramifications of continued data center growth motivate the need to explore energy-efficient methods to operate these buildings. A substantial portion of data center energy use is dedicated to removing the heat that is generated by the IT equipment. Using economizers to introduce large airflow rates of outside air during favorable weather could substantially reduce the energy consumption of data center cooling. Cooling buildings with economizers is an established energy saving measure, but in data centers this strategy is not widely used, partly owing to concerns that the large airflow rates would lead to increased indoor levels of airborne particles, which could damage IT equipment. The environmental conditions typical of data centers and the associated potential for equipment failure, however, are not well characterized. This barrier to economizer implementation illustrates the general relationship between energy use …