Investigation of Down-Draught Effect on The Thermal Comfort Indexes in The Building With Glazing Envelope

Employing large windows in the modern buildings is one the most popular approach among architects and buildings designers but the increase of energy consumption of the building due to down draught effects caused by large windows is one of the challenges against this type of design. Also, preventing of utilizing traditional heating system adjacent to the window is another concern of the approach. In this study, the use of forced convection heating system to mitigate the down-draught effects is simulated by computational fluid dynamic method for three different configurations of the warm air registers mounted (a) under the window; (b) alongside walls and (c) in mixed form under and above the window. The results were investigated by comparing air temperature and velocity distribution in the space and also the thermal comfort conditions were analyzed through Fenger model. The results showed that the third configuration of the inlet registers which they are installed beneath and above the window, is in satisfactory concord to ASHRAE standards and ISO 7730 such that at ankle and breathing height of sitting and standing position, the comfort condition indexes are in regular range of the standards.