Are the pressure losses comparable in all-air and ACB systems?
Yes. When comparing the two systems, it is necessary to take into account the AHU losses, filters, outside air and return air path losses, the supply air duct loss and then the VAV box and its downstream ductwork and outlets or the ACB terminal unit. As the duct system for the active chilled beam system is much smaller, it’s possible to design the duct system at lower velocities with no concern about space constraints, thereby reducing the system fan operating pressures. Duct system design aside, the pressure losses of the VAV box, downstream duct and supply outlets will be very close to or higher than the active chilled beams terminal unit typically selected at 0.5″w.c or less.
