The design of a natural ventilation strategy requires the establishment of the location and size of a series of purpose provided ventilation openings (PPOs). The success of the design is dependent on knowledge of the aerodynamic performance of the PPOs often described by their geometry (normally an area) and resistance to airflow. The incorrect interpretation of this information can lead inappropriate ventilation strategies and buildings that overheat and have an excessive energy demand.
The free area of a PPO (Af) is defined as the area free of obstruction, but its measurement can be subjective and prone to error. The project will develop a more robust system of measuring opening area using laboratory methods leading to unambiguous tools for use in industry.
The project will go on to further question the assumptions of the orifice equation used to estimate air flow, and to provide methods to account for the situations where these assumptions break down. It is hoped that the outcome of this work will reduce design errors and lead to successful natural ventilation strategies and to better buildings.