Ventilation control is often described in terms of flow rates, while ventilation performance is often described in terms of age of air. This paper presents a methodology for modeling multizone ventilation systems that integrates these two concepts. The result is a model that may be used both for ventilation control and for ventilation performance evaluation. Ventilation effectiveness and several different calculation methods for multizone systems are described along with a simple method for translating ventilation requirements, which are normally described in terms of outdoor airflow rates, to age-of-air requirements and vice versa. A new ventilation control strategy based on this model is described. The strategy minimizes the amount of outdoor air required to maintain the age of air at specified locations at or below specified levels. An example illustrates the benefits of the strategy.

Paper from IAQ 1997 -- Design, Construction, and Operation of Healthy Buildings: Solutions to Global and Regional Concerns