ABSTRACT
Ductwork is a vital element of many ventilation systems, whether natural or mechanical. In fact, a duct system is the most common answer to the need for a ventilation system that involves the transport of ventilation air independently of room air motion. There are four major reasons for this need (Malmström, 2002):
to ease the control of airflow rates within the building;
to enclose polluted exhaust or extract air;
to keep supply air clean and conditioned; and
to make heat recovery from exhaust air possible.
