Gives an extensive list of literature on the topic and provides a detailed analysis of several aspects of the problems which can occur. States that good ductwork design and installation are key to providing well balanced ventilation systems, and lists a number of fundamental handbooks which carefully outline the essential elements of designing ventilation air ductwork. Describes various methods including the constant velocity method, the velocity reduction method, the equal friction method, and the static regain method. Proportional balancing is one suggested method to overcome the problems of time consuming measurements to check damper settings. States that a common inference in the literature is that imbalances of outdoor airflows lead to high energy consumption in rooms with high outdoor rates and deteriorated air quality in rooms with low outdoor airflow rates. By balancing the airflows, the average air quality and energy efficiency in a building can both be improved . Poorly balanced ventilation will cause excessive airflows in some offices which are not economical and will most likely cause draughts. Emphasises the importance of proper maintenance and operation of ventilation systems in general, and the balancing of airflows in particular. Also discusses ventilation system balancing and re-balancing after duct cleaning has been undertaken.