By using an innovative combination of existing HVAC technologies, a displacement ventilation system has been developed and field tested. With plug flow ventilation, measurements in a simulation room and commercial installations have revealed improvements to recognized parameters of acceptable indoor air quality. A simulation room was first constructed for the purpose of testing a variety of air distribution methods. The system which demonstrated the most effective results consisted of a raised flooring system with perforated metal plates covered with porous carpet. Supply air below ambient temperature (20.degree.C) was supplied from ducts below the perforated flooring, rising in a vertical pattern to displace the warmed room air. In the simulation room, the return air flowed through an electronic air cleaner to remove more than 80% of the RSP. The air then passed through an acid-treated activated carbon filter to remove gas phase components. The treated return air was then mixed with outside air. The filtered air was then drawn through conventional heating and cooling coils to adjust its temperature. A comparison of three IAQ parameters was conducted to test ceiling vs. floor introduction of supply air. Results from tests conducted in the simulation room revealed reductions in three parameters compared to conventional ventilation : airborne particulates (reduced from 0.93 to 0.1 mg/m3), nicotine (decreased from 0.26 to 0.015 mg/m3) and ammonia (from 0.53 to 0.07 mg/m3). The same design guidelines were employed for construction of a displacement ventilation system in the lounge of a performing arts center. Tests at the breathing zone during actual occupancy revealed values of carbon dioxide, carbon monoxide, formaldehyde, nicotine, RSP, VOCs, and microorganisms lower than conventionally ventilated room. Temperature and relative humidity levels were consistently even.