Poor design or lack of system sealing can produce inadequate airflow rates at the terminals, leading to discomfort, loss of productivity, and even adverse health effects. C ommercial, industrial, and residential air duct system design must consider (1) space availability, (2) noise levels, (3) air leakage, (4) balancing, (5) fire and smoke control, (6) initial investment cost, and (7) system operating cost.ĭeficiencies in duct design can result in systems that operate incorrectly or are expensive (increased energy) to own and operate.