As shipping containers were designed to be nearly airtight and prevent the flow of air across cargo, interior air temperatures can sometimes be up to 25 degrees higher than exterior temperatures.
In humid climates, storage containers can build up moisture internally that can cause water damage to the paneling or items stored inside. If the container is being used to store items that off-gas Volatile Organic Compounds (VOCs), it is critical that storage containers are modified with proper ventilation.
Adding ventilation to your shipping container can reduce heat, prevent moisture buildup, and allow the dispersal of VOCs that can be dangerous or unhealthy if allowed to build up.
If you plan on using the container for storage, consider the safe storage temperature of the items you intend to store in it. If your storage container will be used as additional office space, ventilation will be required to keep interior temperatures comfortable and improve air circulation.