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

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was less than 12 percent. These values, along with the measured velocities for the wind-drivenflow experiments are presented for the stacks closed case in Table 35 and for the stacks opencase in Table 36. When the stacks were closed, the only location of outflow of air was at thenorthern façade. The inlet windows on the south façade were smaller in size than the outletwindows on the north façade. The inlet windows were 2 cm tall by 12 cm long, whereas theoutlet windows were 2 cm tall by 17 cm long. There were an equal number of windows on thenorth and south façades.Table 35. Average Inlet and Outlet Velocities for Wind-Driven Case: Stacks ClosedSetting 3 Setting 2 Setting 1 Setting 1-83% Setting 1-57%Window Inlet 5.1 m/s 4.0 m/s 2.9 m/s 2.0 m/s 1.0 m/sWindow Outlet 3.2 m/s 2.6 m/s 1.8 m/s 1.3 m/s 0.7 m/sAirflow Balance 10.6% 7.4% 11.6% 7.4% 0.2%Table 36. Average Inlet and Outlet Velocities for Wind-Driven Case: Stacks OpenSetting 3 Setting 2 Setting 1 Setting 1-83% Setting 1-57%Window Inlet 5.1 m/s 4.1 m/s 3.0 m/s 2.0 m/s 1.0 m/sWindow Outlet 2.8 m/s 2.3 m/s 1.7 m/s 1.1 m/s 0.6 m/sStack Outlet 3.1 m/s 2.2 m/s 1.9 m/s 1.0 m/s 0.5 m/sAirflow Balance 6.5% 6.6% 3.3% 9.1% 1.9%The air entered through all of the window openings on the south façade at the same velocity, andexited the north façade with uniform velocity. In the stacks open scenario, approximately 85percent of the air exited at the north façade and the remaining 15 percent of the air exited throughthe stack openings. This was consistent over the range of wind velocities used for the wind-onlycase.7.2.2 Combined Wind-Buoyancy Driven CaseThe addition of heaters to mimic the internal loads to the wind cases resulted in a combinedwind-buoyancy airflow. The heaters were left on at full strength, while the speed of the fans wasadjusted, from 5 m/s down to 0.5 m/s. Both temperature measurements and inlet and outletvelocity measurements were recorded and an airflow balance calculated.The wind speeds that were utilized in the wind-only cases were used in the combined windbuoyancycase. However, with these inlet velocities the wind-driving force dominated theairflow. So reduced fan speeds were used to achieve wind speeds at the inlet windows on thesouth façade of 2 m/s, 1 m/s, 0.7 m/s and 0.5 m/s. The measured inlet and outlet air velocitiesfor the stacks open case are presented in Table 37. As the inlet air velocity decreased, thepercentage of air exiting through the stacks increased. This is shown graphically in Figure 68,where the dashed lines represent the buoyancy case for reference. For the stacks closed case, allof the entering air from the south façade where the wind device is located exited throughwindows located on the north façade. When there is no wind present, under pure buoyancydrivenflow, a greater percentage of the outflow exits through the stacks. As the applied windspeed increases, the percentage of outflow that exits through the stacks decreases.140
Percent Air ExitingTable 38 lists the average exit velocity for the range of inlet velocities for the stacks closedexperiments. As the wind speed at the south façade decreased, the distribution of exiting airvelocities on the north façade displayed distinct variations from first floor to second floor, andeven between the two sets of windows (upper and lower) at each floor level. This occurred forboth the stacks open and the stacks closed cases, as presented in Table 39.Table 37. Air Measurements: Combined Wind-Buoyancy Stacks Open Case5 m/s 4 m/s 3 m/s 2 m/s 1.5 m/s 1 m/s 0.7 m/s 0.5 m/sInlet 5.1 4.1 3.1 2.0 1.5 1.1 0.7 0.5Outlet Windows 2.9 2.3 1.6 0.9 0.7 0.5 0.3 0.2Stacks 2.7 2.2 1.7 1.0 0.9 0.6 0.5 0.5Airflow In (m 3 /s) 0.343 0.275 0.208 0.134 0.101 0.074 0.047 0.033Airflow Out (m 3 /s) 0.323 0.257 0.182 0.115 0.083 0.060 0.038 0.028Airflow Balance 5.7% 6.6% 12.7% 14.9% 18% 20% 20% 17%Table 38. Air Measurements: Combined Wind-Buoyancy Stacks Closed Case5 m/s 4 m/s 3 m/s 2 m/s 1.5 m/s 1 m/s 0.7 m/s 0.5 m/sWindow Inlet 5.0 4.0 3.0 2.0 1.5 1.1 0.7 0.5Window Outlet 3.2 2.6 1.9 1.1 0.8 0.6 0.4 0.3Airflow In (m 3 /s) 0.336 0.269 0.201 0.134 0.101 0.074 0.047 0.034Airflow Out (m 3 /s) 0.307 0.249 0.182 0.110 0.077 0.058 0.038 0.029Airflow Balance 8.8% 7.4% 9.7% 17% 22% 22% 19% 14%100.0%90.0%80.0%70.0%60.0%50.0%WindowStack40.0%30.0%20.0%10.0%0.0%0 0.5 0.7 1 2 3 4 5Entering Air Velocity (m/s)Figure 68. Percent of Air Exiting Through Stacks versus Windows for Range of Applied WindVelocities for Combined Wind-Buoyancy Case141
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Thesis Committee:Leon R. Glicksman,
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Table of ContentsTable of Contents
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7.1.3 Full Model Case .............
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Figure 41. Wind Direction Data for
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List of TablesTable 1. Energy End U
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Table 64. Comparison of Dimensionle
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Chapter 1.0IntroductionEnergy consu
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insulated building envelopes with t
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energy usage and efficient design.
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Figure 3. European Patent Office Bu
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selecting boundary conditions) to e
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2.2.1 Buoyancy-Driven VentilationVe
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Figure 7. Neutral Pressure Level fo
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Combined wind-buoyancy flow is more
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design. The depth of natural ventil
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of cooling required by 30 percent o
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considered when determining how the
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environmental conditions are examin
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As natural ventilation is prevalent
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Chapter 3.0Evaluation of Prototype
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Figure 12. Interior Atrium ViewFigu
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Table 8. Prototype Building Window
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Figure 15. HOBO® H8 Series Tempera
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Finally, airflow visualization was
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only is the airflow almost never at
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Table 10. Window Bag Device Measure
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Mon 7-21Tue 7-22Wed 7-23Thu 7-24Fri
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12:00 AM1:00 AM2:00 AM3:00 AM4:00 A
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27-Jul27-Jul28-Jul28-Jul29-Jul30-Ju
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A range of air exchange rates was f
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the windows on the second floor, or
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Total Electric (kWh/m2)Total Gas (k
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movement, Houghton Hall has much le
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Chapter 4.0Modeling and Visualizati
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for future design of similar type b
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lower and upper openings and natura
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the acceptable diffusion rate, or
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applications involving full-scale b
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digital camera with both manually o
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Chapter 5.0Dimensional Analysis and
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u oHgHT2uocu Hpo1Re Ar1Re Pr(5.7)(5
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X HM X HP(5.16)5.3.2 Kinematic Sim
Page 89 and 90: Radiation was found to have an impa
Page 91: height is used for the full-scale b
Page 94 and 95: 6.3 Model Descriptions6.3.1 Physica
Page 96 and 97: Figure 30. Floor Plan of the Protot
Page 98 and 99: Figure 31. North Facade of Model wi
Page 100 and 101: Monitoring data collected from the
Page 102 and 103: By default, there was no accounting
Page 104 and 105: 40-location card inserted into the
Page 106 and 107: 6.5 ExperimentsTo evaluate the mode
Page 108 and 109: modified to determine the impact of
Page 110 and 111: Figure 39. Two Heated Zone ModelWit
Page 112 and 113: minute interval, the model was assu
Page 114 and 115: Figure 42. Cross-Section of Wind-Ge
Page 116 and 117: Table 25. Wind-Assisted Ventilation
Page 118 and 119: Figure 44. Heaters and Zones for a)
Page 120 and 121: Height from Floor (m)Height from Fl
Page 122 and 123: Where V is the outlet velocity, A o
Page 124 and 125: Table 32. Conduction Heat Loss for
Page 126 and 127: a) Air Modelb) Water ModelFigure 50
Page 128 and 129: Height from Floor (m)The temperatur
Page 130 and 131: Height from Floor (m)In the atrium
Page 132 and 133: First NorthUpper Window 0.17 m/s -0
Page 134 and 135: Height from Floor (m)the column at
Page 136 and 137: Height from Floor (m)Height from Fl
Page 138 and 139: Height from Floor (m)3.53.02.52.01.
Page 142 and 143: Table 39. Variation of Outlet Wind
Page 144 and 145: temperature of the air was the same
Page 146 and 147: 3.532.521.55m/s4m/s3m/s2m/s1m/s1.5m
Page 148 and 149: 3.532.521.55m/s4m/s3m/s2m/s1m/s1.5m
Page 150 and 151: The average and exhaust internal bu
Page 152 and 153: Table 43. Calculated Wind and Buoya
Page 154 and 155: In the last two lines, for both the
Page 156 and 157: Figure 80. CFD Simulation of the Te
Page 158 and 159: uoyancy case the air from the groun
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Page 162 and 163: windows of naturally ventilated bui
Page 164 and 165: difficult to select the boundary co
Page 166 and 167: simulations are able to do would al
Page 168 and 169: Bordass, W.T., A.K.R. Bromley and A
Page 170 and 171: Linddament, M. 1996. Why CO2? Air I
Page 172 and 173: 172
Page 174 and 175: MODEL: K20-8SERIAL: 10047RECORDER_I
Page 176 and 177: 2 Boiler-3 50.00 C1 N1 1.0 ON ON OF
Page 178 and 179: |PW|DESCRIP |KW |KWH|KVA|KVH|------
Page 180 and 181: 2:5 ;day_ofYr17:P30 ;EOT = 0.000075
Page 182 and 183: 2:3136:P30 ;DUM2 = -0.040891:-4.089
Page 184 and 185: ;7:21 ;input location;8:0 ;mulptipl
Page 186 and 187: ;79:P22 ;EXC w/DELAY (only for dela
Page 188 and 189: 1:45 ;port5 (homeSense)2:31 ;exit l
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13:P95 ;ENDIF14:P95 ;ENDIF15:P3 ;pu
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2:20 ;RH30:P70 ;sample1:12:20 ;RH31
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194
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Five Windows Open: Upper versus Low
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One Window Open: Upper versus Lower
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25 cm / 3 m 24.33 26.62 22.68 22.93
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25 cm / 3 m 24.07 25.26 22.65 22.78
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Two Stacks Open Temperature Stratif
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Stacks Closed Temperature Stratific
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2.3 24.31 24.65 24.781.4 23.35 23.6
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0.6 20.56 20.67 20.94 21.22 21.41 2
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