Testing and optimizing the performance of a floor-based task conditioning system

During recent years an increasing amount of attention has been paid to air distribution systems that individually condition the immediate environments of office workers within their workstations. As with task lighting systems, the controls for these 'task conditioning' systems are partially or entirely decentralized and under the control of the occupants. Among the primary types of task conditioning systems (floor-, desktop- and partition-based), floor-based designs are the most common, having been widely developed and used in South Africa and Europe, and are now gaining acceptance in the United States. This paper reports the results of recently completed laboratory measurements investigating the thermal performance of a floor-based task conditioning system. The experiments were performed in a controlled environment chamber configured to resemble a modern office space with modular workstation furniture and partitions. Tests were conducted to study the effects of supply volume, supply temperature, supply direction, and heat load levels in the space. In addition to detailed temperature and velocity measurements, a new skin-temperature-controlled thermal manikin was used to evaluate the non-uniform thermal environments produced by the floor-based system, in both sitting and standing positions. Under the low to intermediate supply volumes investigated in this study, the overall performance of the floor-based system resembled that of displacement ventilation systems. Primarily by controlling supply volume the floor-based system can be operated to maintain acceptable thermal comfort in the occupied zone of the building, while at the same time taking advantage of the temperature stratification inherent in displacement flow to achieve savings in space conditioning energy use.