Skip to main content

Research Repository

Advanced Search

A review of ventilation opening area terminology

Jones, Benjamin M.; Cook, Malcolm J.; Fitzgerald, Shaun D.; Iddon, Christopher R.


Malcolm J. Cook

Shaun D. Fitzgerald

Christopher R. Iddon


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.

Many definitions of PPO area are used by standards, guidelines, text books, and software tools. Each can be assigned multiple terms and a single term can be assigned to different definitions. There is evidence that this leads to errors in practice. An effective area of a PPO, defined as the product of its discharge coefficient and its free area, is proposed as a standard description because it is unambiguous and its measurement is governed by recognised standards. It is hoped that PPO manufacturers will provide an effective area as standard and that its use will be recognised as best practice. It is intended that these steps will reduce design errors and lead to successful natural ventilation strategies and better buildings.


Jones, B. M., Cook, M. J., Fitzgerald, S. D., & Iddon, C. R. (2016). A review of ventilation opening area terminology. Energy and Buildings, 118,

Journal Article Type Article
Acceptance Date Feb 27, 2016
Online Publication Date Mar 5, 2016
Publication Date Apr 15, 2016
Deposit Date Nov 7, 2016
Publicly Available Date Nov 7, 2016
Journal Energy and Buildings
Print ISSN 0378-7788
Electronic ISSN 1872-6178
Publisher Elsevier
Peer Reviewed Peer Reviewed
Volume 118
Keywords Natural ventilation; Design; Standards; Effective area; Equivalent area; Free area; Policy
Public URL
Publisher URL
Copyright Statement Copyright information regarding this work can be found at the following address:


Jones et al - A review of ventilation opening area terminology.pdf (450 Kb)

Copyright Statement
Copyright information regarding this work can be found at the following address:

You might also like

Downloadable Citations