The problem of turbulence intensity measurement in comfort ventilation

The turbulence intensity is an important feature of the turbulent airflow and draught sensation in ventilated rooms. The turbulence is often measured with hot-wire (in fluid mechanics applications) and hot-sphere sensors (in indoor air comfort investigations). In this paper the turbulence was measured with hot-wire and hot-sphere sensors in a full-scale single office room based on air speed measurements. Isothermal air injection was applied and the measurements were conducted on eight different inlet volume flow rates. The two applied sensors resulted two independent samples, which were evaluated with different statistical methods. The results showed that there was not significant difference between the standard deviation and average of the measured samples. Thus, the two sensors statistically gave the same results on probability level 95%. The referred international standards suggest an average turbulence intensity 40% for draught comfort design in mixing ventilation. The results showed that most of the measured turbulence intensities were less than the recommended standard turbulence intensity.