Use of Average Ventilation Coefficients in Predicting of the Hourly Average Indoor Airspeed

Federal University of Alagoas, Brazil

Abstract: The present work aims to test the hypothesis that the average ventilation coefficient has an irrelevant variation, as a function of wind speed for predicting the hourly average indoor airspeed from hourly wind speed and direction data. The method is based on a parametric analysis, to test the effect of different combinations of wind direction and speed on a building model. Computer simulation with the ANSYS CFX tool generated indoor airspeed data to calculate the average ventilation coefficients. These data showed that the average ventilation coefficient could be considered invariant, for a given wind direction and building geometry, in the precision of one-tenth of a meter per second (0.1 m/s) and for wind speeds between one and five meters per second. The ventilation coefficients effectively estimated the hourly average indoor airspeed based on the climate file's wind speed and direction data. These coefficients contribute to greater efficiency in studies on the annual frequency of thermal comfort in naturally ventilated buildings, based on adaptive comfort models and computer simulation.