Evaluating the performance of a Windcatcher system using wind testing.

Increased global warming and deterioration of the ozone layer have stimulated interest in the use of renewable energy systems. Natural ventilation is increasingly being employed in modern buildings to minimize energy consumption and the release of harmful emissions to the environment. Innovative natural ventilation techniques such as the windcatcher and solar chimney have facilitated the effective use of natural ventilation in a wide range of buildings for increasing the ventilation rate. In addition to bringing energy savings, these environmentally friendly technologies also help create healthier interiors for occupants. This paper presents an experimental study for evaluating the performance of windcatchers for natural ventilation in buildings. Wind tunnel and smoke visualisation tests were carried out on a full scale circular windcatcher to evaluate its performance when attached to a model test room. The windcatcher was divided internally into four segments for the purpose of air supply and extract. Pressure coefficients distribution and volumetric airflow were measured for various wind speeds and three different wind directions. The tests were carried out for wind speed in the range of 0.5-5 m/s giving an air change rate in the test room (13.8m 3 in volume) of 1.5 to 6.8 ac/h. The external pressure coefficient distributions were complemented by the smoke visualisation tests. The smoke tests indicated that the air was supplied into the test room through segments with positive external pressure coefficients and extracted out of the test room through segments with negative pressure coefficients with little short circuiting. The results of this experimental investigation demonstrate the potential of the windcatchers for natural ventilation purposes in buildings.