The construction of energy efficient buildings is a major interest of building research centers around the world , since any saving in energy here can be directed to industrial purposes. The effort was therefore concentrated upon reduction of building energy, which is consumed by various systems such as air conditioning, being
major consumer of the energy supplied to a building. Other but small consumers include lighting, pumps, appliances. Hence, as a building designer succeeds to reduce the energy needed for an air conditioning system or to replace the later by some natural ventilation arrangement that carries the heating load, the building is then energy efficient. In the present work the possibility of heat removal through natural ventilation is examined for various wind directions (0, 45, 90, and 135)o, and window configurations and combinations. The investigation was carried out in a wind-tunnel test facility which was designed, built and tested at the Housing and Building Research Center (HBRC), Guirguis [1]. The tunnel floor was provided with rotatable disc on which the model was mounted and set at any required angle (α) relative to wind direction. The present suction-type wind-tunnel test facility has a working section 1.0 m wide, 1.0 m high and 2.0 m long, serving the purpose of test building models of size that permitted the observation of phenomena with reasonable accuracy. The duct
provided with a standard-profile intake. Turbulence-generating grids were constructed and mounted so distance ahead of the test model to obtain turbulent “shear-like” ABL (Atmospheric Boundary Layer) profile
. A simplified parallelopiped-shaped building model was constructed from 5-mm thick Plexiglass sheet and its floor was provided with heating elements (for thermal measurements). However, for effective natural ventilation, the design of building openings (windows, wind shafts, balconies, … etc) must consider the structure of prevailing wind and its characteristics (speed, direction, turbulence, … etc). Because data for optimum design of openings for acceptable comfort (temp., humidity, contamination, and air motion) is not adequate, it would be important to provide such data through systematic testing in a research study that considers all possible variables. In the present work, the effect of wind direction and window size and arrangement on two thermal comfort indices (predicted mean vote (PMV) and predicted percentage of dissatisfied (PPD)) was investigated in an attempt to determine the optimum building angle façade angle relative to wind direction. The PMV and PPD values were derived from measurements and plotted for each wind speed. The experimental study demonstrated that wind condition has significant effect on temperature distributions on internal surfaces as well as in interior space of a typical building and consequently on the thermal comfort indices. |
