Experimental validation of different air flow correlations for natural single sided ventilation

Abstract

Humans in the developed countries spend most of their time indoors. Therefore, the importance of good indoor air quality is evident. Natural ventilation is common for the air supply in many private residential buildings as well as in offices around the world. It grants the hygienic minimum or even more air exchange, protects from moisture damages and can provide good thermal comfort by intensive night ventilation in summer. The window opening process can be automated to compete with the air quality resulting from mechanical cooling and ventilation. Considering energy efficient buildings with controlled natural ventilation, the air exchange rate provided by window openings is a crucial design variable. Multiple correlations from literature allow the determination of air change rates for various window opening configurations and types under static conditions. This work compares calculations from these equations with field measurement data. Most accurate correlations are identified. Limitations and challenges for technical planners are pointed out. Traces-gas (TG) measurements with the Constant Concentration Method (CCM) were carried out, collecting five minute mean values of air change rates. Temperature differences ranging from 0K to 21 K and wind velocities between 0m/s to 1.5m/s were monitored. The window types examined are bottomhung and side-hung windows. This work focuses on single sided ventilation.