In an in-room solution that adopts overhead air supply through air ducts, the net height...

For an in-room cooling solution that usesoverhead air supply with air ducts, sufficient vertical space is required to accommodate the ductwork, airflow distribution components (such as plenums, turning vanes, flexible connectors, and diffusers), cable trays/pipes that may share the overhead route, and the necessary maintenance clearance. If the net height is too low, the duct cross-section becomes constrained, which increases airflow resistance and static pressure, reduces delivered airflow volume, and can cause uneven air distribution. This leads to hot spots, higher fan power, and difficulty maintaining stable supply/return temperature control. In Huawei data center air-conditioning design guidance, overhead ducted supply is therefore matched with aminimum net floor height requirement of 4 m, ensuring ducts can be sized correctly for the target airflow, noise, and pressure limits while preserving safe installation and maintenance space. A 3 m net height is generally suitable for non-ducted in-room layouts, but becomes insufficient once full overhead ducting is introduced.