Demand-controlled ventilation (DCV) systems save energy by using building occupancy indicators that usually measure CO2 levels to regulate the amount of outside air that is drawn in for ventilation. But DCV systems are not widely used, because their cost-effectiveness has not been clearly defined, their benefits have not been demonstrated or documented in the field, and design guidelines are rarely available.

Researchers performed an economic analysis of DCV with the help of a computer simulation known as VSAT (Ventilation Strategy Assessment Tool). The analysis determined the conditions under which DCV is most likely to be cost-effective. In addition, field tests were conducted to verify the savings and identify potential problems in the application of DCV. The results also included a set of design recommendations.