Analysis of cooling characteristics in datacenter using outdoor air cooling

Advancements in information technology have proceeded with developments in information and communication technology (ICT), increasing the demand for building datacenters. The datacenter we studied is located in Ishikari, a cold region in Hokkaido, Japan. The data center cools its electrical devices by outdoor air. We argue that this cooling system is more efficient than other more conventional systems. This paper comprises five sections. In Section 1, we present the background for our work and our objectives. In Section 2, we give an overview of the Ishikari datacenter and discuss the temperature characteristics obtained from annual measurements. We then discuss two problems, short circuit (cool air is exhausted from the server room without passing through the server racks) and recirculation(hot air exhausted from electronic devices goes back through an non-operational part in a rack to the cool area in a server room). In Section 3, we assess the observation results given in Section 2 by using indicators we introduce. The room exhaust-heat efficiency was 0.71 in room A and 0.67 in room B. This means that about 30% of cooling air did not pass through the devices. The equipment reabsorption ratio was 0.30 in room A. In section 4, we discuss our estimation of the annual power consumption for the ventilation flow ratio by using four different patterns. The patterns differed depending on the air conditioning supply-air temperature; 18°C or 27°C, and whether a cap on the operational part in server racks was set. We found that the best method of controlling the cooling system was an air conditioning supply-air temperature of 27° C, set cap, and ventilation flow ratio of 0.51. With this method, the annual power usage effectiveness of this data center was estimated to be 1.11 in room A. In Section 5, we summarize the results of our research.