FFUs are an alternative to HVAC systems in a less stringent class of clean rooms. FFUs are often used in projects with height restrictions, rather than HVAC systems where the installation of makeup air ducts and recirculating air needed require much more space. FFU configuration is often a cost effective option, if you don’t need to cool your room (low heat gain), since it uses the air directly from the main building. This eliminates the need for a second ceiling above your cleanroom to create a plenum.
