Chapter 19 of the 2020 ASHRAE Handbook-HVAC Systems and Equipment examines duct construction and presents construction standards for residential, commercial, and industrial HVAC and exhaust systems. In this chapter, system design and calculation of a system’s frictional and dynamic resistance (total pressure) to airflow are considered. Proper duct insulation eliminates excessive heat gain or loss. Lack of sound attenuation may lead to objectionable noise levels. 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. Commercial, industrial, and residential air duct system de- sign 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.
