Abstract This paper describes a series of laboratory experiments that investigated the airflow interactions that take place between components in louvered ventilators. The context of the work was to improve the design and performance of ventilators used in natural ventilation systems in buildings. The study sort to analyse the measured results, identify any trends and ultimately to derive simple mathematical equations that could be used to describe the airflow behaviour of a given ventilator configuration. Multiple regression analysis was utilised in obtaining relationships between airflow rates, pressure differentials applied across ventilator components, mesh-screen free area, louver blade inclination angles and, where applicable, gaps between louver blades and mesh-screens. The paper introduces some simple generic equations that relate the airflow rate through a ventilator to the prevailing driving force and the constituent components/configuration of the ventilator.