Open parking garages, by definition, have to have how much of two sides of a tier open to the atmosphere?

Open parking garages are designed with adequate ventilation to maintain air quality and ensure safety by allowing smoke and heat to disperse in the event of a fire. By definition, at least 20% of the total area of two sides of a tier in an open parking garage must be open to the atmosphere. This requirement helps to facilitate natural ventilation, reducing the risk of smoke buildup and increasing the safety for occupants and first responders. The criteria ensure that there is a sufficient open area that allows for effective airflow, which is critical in minimizing the risks associated with fire incidents in these types of structures.