Which factor most directly influences the energy use of a ducted HVAC system?

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Multiple Choice

Which factor most directly influences the energy use of a ducted HVAC system?

Energy use in a ducted HVAC system is driven by the resistance the air encounters in the duct network. The blower has to supply enough pressure to push air through the ducts, so the energy it uses depends on how much pressure drop the airflow has to overcome. Duct design choices—how big the ducts are, how long they run, how many fittings and bends there are, how transitions are made, and how well the system is sealed—directly set that pressure drop. Smooth, adequately sized ducts with few unnecessary turns and tight seals lower friction and static pressure, so the fan runs less hard and uses less energy. Poorly designed ductwork with undersized ducts, many bends, long runs, or leaks increases resistance and forces the blower to draw more power to deliver the same airflow. The other factors—how many zones there are, the color of insulation, or where equipment is located—can affect layout or heat transfer but do not influence the fundamental air-pressure losses as directly as duct design does.

Energy use in a ducted HVAC system is driven by the resistance the air encounters in the duct network. The blower has to supply enough pressure to push air through the ducts, so the energy it uses depends on how much pressure drop the airflow has to overcome. Duct design choices—how big the ducts are, how long they run, how many fittings and bends there are, how transitions are made, and how well the system is sealed—directly set that pressure drop. Smooth, adequately sized ducts with few unnecessary turns and tight seals lower friction and static pressure, so the fan runs less hard and uses less energy. Poorly designed ductwork with undersized ducts, many bends, long runs, or leaks increases resistance and forces the blower to draw more power to deliver the same airflow. The other factors—how many zones there are, the color of insulation, or where equipment is located—can affect layout or heat transfer but do not influence the fundamental air-pressure losses as directly as duct design does.

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