This document specifies methods for measuring: the aerodynamic characteristics of cowls, fan assisted cowls and roof outlets; the electrical and acoustic characteristics of fan assisted cowls. This document is applicable to cowls, assisted cowls and roof outlets used in natural, hybrid or mechanical ventilation and that are meant to be fitted onto ducts which project above the roof surface. This document does not apply to: assisted cowls assisted by a device other than a fan (e.g. injection assisted cowls); roof exhaust fans (see EN 13141-4).