An air management system, comprising: a plurality of rows of electrical equipment that are laterally spaced apart from each other, each row providing a flow path from a convection region on a first side of the row to a different convection region on an opposite second side of the row; a plurality of supply aisles and a plurality of return aisles interposed between each other, each supply aisle and each return aisle having a respective room portion that includes a respective one of the convection regions, a respective ceiling portion disposed above the room portion, and a vented barrier portion therebetween, each supply aisle providing airflow downwards from its respective ceiling portion through its vented barrier portion to its convection region, and each return aisle providing airflow flow upwards from its convection region through its vented barrier portion to its respective ceiling portion; and a plurality of air handling units (AHUs) located externally to the plurality of rows; wherein the plurality of air handling units (AHUs) are configured to utilize the ceiling portions of the supply aisles as supply ducts, and utilize the ceiling portions of the return aisles as return ducts, the air management system being characterised in that it further comprises: a supply manifold and a return manifold disposed at an end of the ceiling portions and transverse to the rows of electrical equipment; a plurality of first fans, each associated with the supply manifold and configured to provide airflow between the supply manifold and the ceiling portion of an associated one of the supply aisles; and a plurality of second fans, each associated with the return manifold and configured to provide airflow between the return manifold and the ceiling portion of an associated one of the return aisles; wherein each first fan and each second fan is configured to provide airflow into its associated ceiling portion from its associated manifold in a first mode, and provide airflow into its associated manifold from its associated ceiling portion in a second mode. a plurality of rows of electrical equipment that are laterally spaced apart from each other, each row providing a flow path from a convection region on a first side of the row to a different convection region on an opposite second side of the row; a plurality of supply aisles and a plurality of return aisles interposed between each other, each supply aisle and each return aisle having a respective room portion that includes a respective one of the convection regions, a respective ceiling portion disposed above the room portion, and a vented barrier portion therebetween, each supply aisle providing airflow downwards from its respective ceiling portion through its vented barrier portion to its convection region, and each return aisle providing airflow flow upwards from its convection region through its vented barrier portion to its respective ceiling portion; and a plurality of air handling units (AHUs) located externally to the plurality of rows; wherein the plurality of air handling units (AHUs) are configured to utilize the ceiling portions of the supply aisles as supply ducts, and utilize the ceiling portions of the return aisles as return ducts, the air management system being characterised in that it further comprises: a supply manifold and a return manifold disposed at an end of the ceiling portions and transverse to the rows of electrical equipment; a plurality of first fans, each associated with the supply manifold and configured to provide airflow between the supply manifold and the ceiling portion of an associated one of the supply aisles; and a plurality of second fans, each associated with the return manifold and configured to provide airflow between the return manifold and the ceiling portion of an associated one of the return aisles; a supply manifold and a return manifold disposed at an end of the ceiling portions and transverse to the rows of electrical equipment; a plurality of first fans, each associated with the supply manifold and configured to provide airflow between the supply manifold and the ceiling portion of an associated one of the supply aisles; and a plurality of second fans, each associated with the return manifold and configured to provide airflow between the return manifold and the ceiling portion of an associated one of the return aisles; wherein each first fan and each second fan is configured to provide airflow into its associated ceiling portion from its associated manifold in a first mode, and provide airflow into its associated manifold from its associated ceiling portion in a second mode.