This can be a hard question to answer, and it doesn't always have a definitive answer. Portable fans are great if you have a space that is too open to the elements for a permanent system to be effective. Outdoor gyms or classrooms are great locations for these portable fixtures. Large-scale indoor areas are much more suited to permanent ventilation systems. Indoor gyms, warehouses, factories, and server farms are excellent locations for these more permanent systems. These aren't catch all scenarios though, and sometimes you'll need both a permanent system and portable fan! Each situation is different, so consider your options and needs carefully when trying to decide which fan is needed.