“…To better explain the phenomenon, Figure 15 illustrates the age of air and velocity vector in a plane of the 7th floor under S wind direction. In each floor (Figure 15), the leeward-side rooms are defined as C type (room number of 14,16,18,20,22,24,26) and D type (room number of 15, 17 19, 21, 23, 25). Figure 14, the spatial mean age of air in leeward-side rooms alternates periodically with older air in rooms C than rooms D. That could be due to the strong circulation region in rooms A (Figure 15), causing the wind to flow out of rooms A to blow into rooms D, making rooms D to draw younger air than rooms C. Figure 14(b) shows the distribution of ACH of leeward-side rooms under S wind.…”