The unique features and design requirements of Data Centers utilizing hot or cold aisle containment will be described with a focus on their impact on system design. These include determining the proper temperature and humidity levels entering the unit, humidification and dehumidification, calculating unit airflow, and unique control schemes. With traditional architectures, the temperature and humidity of the air entering the cooling equipment is typically assumed to be equal to that of the air in the space. With containment the temperature and humidity of the air leaving the cooling equipment, the air entering the servers, and the air returning to the cooling equipment must be considered separately. Due to the high temperature of the air entering the cooling equipment the cooling coil is often hot and dry prohibiting the unit from dehumidifying the space. In these cases dehumidification must be done by equipment other than the primary cooling units. Humidification can still be done with the cooling units but care must be taken in the humidity measurement. Determining the unit airflow is also a challenge. Since most of the airflow passes through the servers, unit airflow must be closely matched to the cumulative server airflow. The unit controller must determine the server airflow, or use a proxy, and vary the unit airflow accordingly. Special consideration must also be given to control of the cooling source and in the use of DX equipment.