Experimental study of building natural ventilation with pendulum velocity anemometer

The use of natural ventilation in buildings can largely benefit the energy saving and indoor air environment improvement. However, due to the lack of online high-precision measurement method, it is difficult to obtain real-time natural ventilation of buildings. This study proposes a method with a newly developed pendulum velocity anemometer (PVA) to monitor the natural ventilation in terms of high-frequency velocity speeds, velocity directions and turbulence characteristics at window openings in real time. According to the wind tunnel experiments, the anemometer yielded an overall similarity of 91% with the hotwire velocity anemometer (HVA) regarding the instantaneous minute average velocities. The measurement error was 18% lower than HVA in terms of the inflow and outflow rates at a window opening. The measurement frequency reaches 100 Hz, and 10 Hz is the best sampling frequency through the analysis of time moving average. In addition, the energy spectrum analysis of turbulence is carried out and energy spectrum of natural ventilation is mainly concentrated at 1 Hz. It is noted that this is the first report that PVA being applied in the velocity's measurements, which suggests its promising applications in natural ventilation study.