Presents a guide to help commissioning engineers and maintenance contractors select appropriate test methods to set correct minimum outdoor air rates. States it is intended for use in setting minimum outdoor air rates in mechanical ventilation systems that use modulating dampers to vary the proportion of outdoor air between a fixed minimum and full outdoor air. 

Also provides useful background information on the importance of ensuring that minimum outdoor air is correctly set, when tests should be performed and the type of problems which can occur. 

The guidance was produced from the results of 18 sets of tests of different airflow rate measurement methods. The tests were applied to 14 ventilation systems supplying a range of building types, including a library, lecture theatre, function suite, swimming pool and several offices.