FIELD MEASUREMENT ON THE BASIC PEFORMANCE OF THE NATURAL VENTILATION SYSTEM COMBINED WITH SOLAR CHIMNEY AND UNDERGROUND PIT

The basic performance of natural ventilation system combined with solar chimney and underground pit installed in a new school building and the measured results before the school opening are described. A special measuring unit for average air velocity across the horizontal section of solar chimney was devised to obtain the exhaust volume out of solar chimney. With this method the average air velocity within solar chimney can be derived from the air velocity value of the normally installed anemometer multiplied by the conversion coefficient obtained from multi-point measurements. As a result the exhaust volume out of solar chimney and supply air volume from underground pit variant over time were found almost in equal amount. Difference in natural ventilation volume between in one building block and another could hardly be observed. Air velocity within the solar chimneys turned out highly correlated with solar radiation when the wind speed outside was low and highly correlated with wind speed when solar radiation was small.