Influence of window form and location and the provision of background ventilation on comfort within rooms

Abstract

Comfort conditions in rooms ventilated by trickle vents were investigated experimentally. The conclusion that head-to-ankle temperature gradient is altered by the location of radiators within a room was borne out in this study for single-, double- and triple-glazed windows. At typical external wind speeds, threshold draught air velocity (0.3 m s-1) is not exceeded by the use of either 4000 or 8000 mm2 vents, although to a limited extent the more stringent ASHRAE standard (0.15 m s-1) is not met by the use of 8000 m2 vents. In both cases Fanger's external comfort criteria were satisfied. The tests generally showed a decrease in head-to-ankle temperature gradient when air was entering the room through the vents at higher velocities. The room air and the plume of air rising off the radiators mixed more thoroughly at the surface of the window when located at the room side of the opening, illustrated in this case by tests on 'double' windows. Iso-PMV contour diagrams were used to show the uniformity of pattern where, for example, air is vented from the room rather than supplied to it, and when ventilation air is supplied at low rather than high level. The latter had a marked negative impact on the HAT gradient whereas changing the height of the window sill above the floor had little effect. The gradient was reduced by adding extra layers of glass into the window. Marked local effects were observed as a result of splaying the top and side reveals.