The performance of microprocessor and its associated components has significantly increased but unfortunately, heat dissipation from these components is a growing problem. ASHRAE and Uptime Institute have predicted the increasing heat trends and proposed guidelines based on equipment manufacturer's requirements and customer challenges. The major challenge for the customers among others is to maintain servers at an acceptable temperature to achieve desired reliability and functionality. Efficient cooling is mandatory in order to decrease maintenance cost and power usage. Air flow distribution in a raised floor data center is complex and need to be studied for implementing innovative cooling designs that can sustain lower rack inlet temperatures with the use of less amount of cold air supply by utilizing proper management of hot and cold air. This book introduces cold aisle isolation designs to contain the cold air in cold aisle and prevents hot air infiltration. Additional transient analysis are studied as data centers are highly time dependent with fluctuations in server power and cold air supply.