The definition of air volume is the amount of air that is present in a given space. It is typically measured in cubic feet or cubic meters and is determined by the size of the space and the amount of air that is present. Air volume is important to consider when designing a space, as it can affect the air quality and the comfort of the occupants. Air volume can also be used to calculate the air flow rate, which is important for air conditioning and ventilation systems. Additionally, air volume can be used to measure the pressure of the air in a space, which can be used to determine the efficiency of a heating or cooling system. In summary, air volume is an important factor to consider when designing a space, as it can affect the air quality, comfort, and efficiency of the space.