Methodology for the Evaluation of Natural Ventilation in ... - Cham

Height from Floor (m)14.012.010.01Stack Open2Stacks Open3Stacks Open3Stacks Closed8.06.04.02.00.020.0 21.0 22.0 23.0 24.0 25.0 26.0 27.0 28.0Temperature ( C)Figure 56. Two Zone Scaled Temperature Stratification for Full-Scale Building: In Atrium7.1.3 Full Model CaseWith the full model case using four heated zones, the interactions between the zones for caseswith all of the stacks open, one stack open, and all of the stacks closed were investigated usingboth the physical model and numerical simulations.The thermocouples were located at the columns for each level and within each heated zone. Forthe buoyancy-driven case, whether or not the stacks were open or closed influenced the locationof the neutral plane within the model. This in turn affected the airflow patterns and direction ofairflow at the first floor upper windows. When any of the stacks were open, the air flowed inboth sets of windows at the ground floor level, and in both sets of windows at the first floor levelfor both the north and south façades. Air exited through both sets of windows at the second floorlevel and through the stacks at the roof of the atrium, as shown in Figure 57. In the case whereall three stacks were closed, air still entered both sets of windows at the ground floor level, andexited both sets of windows at the second floor level. However, at the first floor level, the airentered the lower set of windows at both the north and south façades and exited the upper set ofwindows at both façades.Table 34. Measured Air Velocities for Full-Model Stacks Open and Stacks Closed CasesStacks Open Velocity Stacks Closed VelocityGroundUpper Window 0.69 m/s 0.54 m/sLower Window 0.74 m/s 0.67 m/sFirst SouthUpper Window 0.13 m/s -0.18 m/sLower Window 0.42 m/s 0.32 m/s131