From the document: "Automatic rooftop vents are installed in some occupancies to allow smoke and heat to escape, thereby improving visibility for firefighters, minimizing property damage, and confining a fire to a smaller area. Vents may be passive, such as the illustrated shrink-out plastic vents, or active, meaning they operate by fusible link, remote operation or manual release on the rooftop. Rooftop vents are found most often in storage occupancies and some legacy applications for buildings that have extremely large areas. Smoke and vents, however, are controversial in fire protection. For example, in buildings protected by automatic sprinklers, water discharge at the ceiling may cool the thermal plume to the level where the vents are unable to operate automatically. Conversely, if rooftop vents are installed in nonsprinklered properties, experience has shown that fire conditions are worsened by the operation of too many vents."
Coffee Break Training - Fire Protection Series No. FP-2014-37
United States Fire Administration: http://www.usfa.fema.gov/