Abstract
Data center energy efficiency is becoming a huge topic of research as more IT infrastructure moves from local resources into the cloud. New data centers designed with energy efficiency in mind have achieved impressive results, but legacy datacenters (10-20 years old) make up a significant portion of the total data center space in the U.S. These sites can benefit the most from having an independent energy audit done with the focus on using new technologies to save substantial energy while maintaining reliability. One of these new technologies is wireless mesh sensor networks. Wireless mesh sensor networks allow large amounts of sensors to be deployed without running expensive power and communication cabling to the sensors. This technology allows a very granular view of the pressure and temperature conditions in real time on the data center floor. This large amount of real time data also provides a factor of safety when changes are made to the cooling system in the quest for energy savings. Because IT loads in data centers change frequently, it is difficult to match cooling capacity with the heat load in the room and as a result, there is usually too much or too little cooling in the data center. Estimating how much energy may be saved depends on determining the factors that affect the cooling efficiency of the data center. This study seeks to determine how physical variables such as floor depth, CRAH arrangement, fan types, fan speed, perforated tile placement and IT equipment layout impact sub-floor pressure distribution. If the subfloor pressure is evenly distributed the fan speeds can be run lower, resulting in increased data center cooling efficiency. In the study thousands of wireless sensors are installed throughout a data center as part of an environmental monitoring and control solution for a large telecommunications company. These wireless devices are capable of monitoring the sub-floor pressure, subfloor temperature, CRAH supply and return temperatures and server rack inlet temperatures at three different heights. When changes are made to the fan speed settings, or supply air temperature, the wireless sensors will capture the changes to the sub-floor pressure and server rack inlet temperatures. The data from the wireless sensors is time stamped and sent wirelessly every 5 minutes back to a central server. This server uses a MySQL database to organize and store all the sensor data. This data can then be accessed and exported for analysis. Once the impacts of these variables have been established, optimal energy savings improvements can be made and are provided in the study.