Immediately underneath the HVLS Fan, airflow is pushed downward. Outside its diameter, the airflow transitions to horizontal air flow, providing comfortable airflow over a large area.
Directional Fans and Airflow
Directional fans create a unidirectional airflow pattern that moves air to the area in front of the fan. Directional fans are most often used to cool occupants in crowded areas where overhead fans cannot be safely installed. In addition, advanced directional fans feature variable speed controls that allow the user to adjust the airflow for optimal comfort.
Using Fans to Improve Ventilation
Fresh air is often not evenly distributed throughout a space. For example, one of the most common air distribution configurations for HVAC systems is an overhead supply and overhead return. In common heating applications, this ceiling configuration results in severe stratification of the heated supply air and room air layers, which prevents fresh air from circulating to occupant level. To compensate for this, ASHRAE 62.1 Ventilation for Acceptable Indoor Air Quality requires that ventilation rates be increased by 20% to provide the necessary amount of fresh air to room occupants. However, in a room with an HVLS ceiling fan stratification, the air layers are well mixed, so the fresh air supply can reach occupant level.
In naturally ventilated spaces, fresh air is passively distributed throughout the space, so localized areas of stagnant air pockets can occur, resulting in poor air quality and contaminant accumulation. Fans disperse these air pockets and increase the circulation of fresh air, evenly distributing it throughout the space and improving indoor air quality (IAQ).
