Displacement ventilation performance - office space application

Displacement ventilation is a method that provides conditioned air to indoor environments with the view to improve air quality whilst reducing energy usage. These systems have been employed in industrial applications, notably in Scandinavia, for many years and have gained in popularity in office building spaces in recent years. Measurements of velocity and temperature fields have been performed in three modern office spaces to analyse the performance of the incorporated displacement ventilation system0>, based on thermal comfort and temperature gradient assessment<2>. The measurements at one of the sites were used to verify the predicted data obtained by a microclimate computer model based on computational fluid dynamics (CFD) techniques. The model was subsequently used to study the effect of cold surfaces, infiltration, floor obstructions and supply air flow rates. Although the application of displacement ventilation is more difficult in office spaces with low ceiling heights, acceptable conditions were measured in two of the three sites considered in this study. However, both measurements and predictions indicated that secondary air flows resulting from infiltration and cold surfaces can adversely affect the ventilation performance and reduce thermal ·comfort. In the application of displacement ventilation care should be taken to minimize these extraneous effects.