The effect of urban micro-climate on indoor-outdoor air exchange

An idealised, staggered array of 9 6m 3 cubes was built to gain an understanding of the influence of other buildings on the natural ventilation rate of a building. The instrumented cube contained 24 temperature measurements, 32 surface pressure taps, CO2 sensors and 2 sonic anemometers, with 5 more placed outside to measure wind velocities. Ventilation rate was measured when the cube was sealed, single-sided and cross-ventilated, when isolated and when in the array. Normalised ventilation rate for single-sided cases responded to a range of different flow features, such as channelling and shielding, some of which may cause ventilation rates experienced for the cube in the array from certain directions to be higher than for an isolated cube. The array and wind-angle influenced the internal conditions, causing the internal jet to shift in position with a 10° wind direction change.