Privacy is a key feature of any office design and fitout. Over the years, designers have tried to specify partition materials with high acoustic ratings and tests. However, the problem comes from something that the designers usually overlook i.e. the mechanical design of the office.
When designing the mechanical drawings for an office, the engineers are usually unaware of the client’s requirements related to sound and sensitive areas. The engineer’s job is to design the HVAC drawings in a way that not only satisfies required cooling for different areas, but to create the ducting network that is most economical to produce and quick to execute on site.
This leads to overlooking of the fundamental concepts of sound transmission through the return ducts.
Yes, return air from the offices is sucked into the ceiling due to the negative pressure created by the FCU (Fan Coil Units), installed above the ceiling.
The easiest solution is to install the main duct in a common area and to give branches to each office with a volume control damper.