Evaluation of displacement ventilation for high ceiling areas.

A study is being conducted to assess the performance of displacement ventilation in high-ceiling areas such as commercial and industrial manufacturing facilities. These areas, which can range from 5 to 20 meters in height, often feature high internal heat loads and contaminants associated with heat sources. Very little performance data exists for displacement ventilation installations in high-ceiling areas, particularly any which account for the influence of wall temperature. In this ongoing study, several experiments are being conducted in a room equipped with both a high ceiling (6.5 meters) and a displacement ventilation system. In addition to traditional person, computer, and lighting loads found in offices, the study also evaluates system performance with higher intensity manufacturing-inspired loads. The performance of the system has been evaluated by use of air temperature, tracer gas, and velocity measurements as well as wall, floor, and ceiling temperature measurements. Results of the measured data will be used to validate a CFD program previously validated for small offices and classrooms with a ceiling height of 2.4 meters. These collected data will also help to extend the applicability of current displacement ventilation guidelines to buildings with higher ceilings and higher intensity internal heat loads. Initial results of two cases are presented here - one, a cubicle-style office and the other, an open-plan office without partitions. The displacement system performed well in both cases. Measurements show that the walls in this high space induce large convective air flows and contribute greatly to the radiant heat load in the occupied zone.