This paper proposes a server model that can be applied to simulating the annual cooling energy consumption of data centers and an analysis of its impact. Recently, aisle containment architecture and the variable air volume system have been widely adopted in the data center industry because of their superior indoor thermal management and cooling energy savings. However, the current simulation method, which fixes the server heat generation and the supply and return air temperature difference of the computer room air handler (CRAH), does not correctly reflect current cooling systems. In this study, a server model was developed that accounts for server thermal characteristics - including server power, fan airflow, and exhaust temperature - according to the given CPU utilization and temperature. After the proposed server model was validated, the annual cooling energy consumption was simulated for modular data centers with an air-side economizer and high ambient temperature. Unlike the conventional method, the proposed model showed that the cooling energy consumption increased when the CRAH supply air temperature was higher than 19 C because of the increase in fan energy consumption. (C) 2014 Elsevier B.V. All rights reserved.