In air-cooled energy storage systems (ESS), the air duct design refers to the internal structure that directs airflow for thermal regulation of battery modules. This ventilation setup plays a key role in preventing overheating, enhancing battery life, and supporting stable system. VA Program Offices, project teams, designers and constructors, are obligated to our Nation's Veterans and taxpayers to make the most effective and efficient use of resources, by providing a continuum of safe, secure, high quality, high performance, and high value environments of care and service. This chapter covers the primary systems found on most aircraft. These include the engine, propeller, induction, ignition, as well as the fuel, lubrication, cooling, electrical, landing gear, and environmental control systems. This design is critical in maintaining safe operating temperatures, extending battery lifespan, and. able, saving time, space and energy consumption.