Application of the constant concentration technique for ventilation measurement to large buildings.

The British Gas 'Autovent' system utilises the constant concentration technique and was developed for measuring ventilation rates in dwellings. It has recently been used in two large open-plan buildings, a school nursery and a factory unit, and the opportunity was taken to carry out special tests to assess its validity in such buildings. The reason why these tests were needed, the nature of the tests and the results obtained form the main content of the paper. The evidence from the tests strongly indicates that the system is suitable. This evidence is supported by the ventilation measurements themselves, examples of which are presented.