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

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Table of ContentsTable of Contents .......................................................................................................................... 4List of Figures ................................................................................................................................ 7List of Tables ............................................................................................................................... 10List of Tables ............................................................................................................................... 10Acknowledgements ..................................................................................................................... 13Chapter 1.0 Introduction ..................................................................................................... 151.1 Building Energy Use ..................................................................................................... 161.2 Difficulties in Predicting Natural Ventilation ............................................................... 171.3 Examples of Naturally Ventilated Buildings ................................................................ 181.4 Goals of this Research .................................................................................................. 221.5 Scope of document ........................................................................................................ 22Chapter 2.0 Natural Ventilation ......................................................................................... 252.1 Introduction ................................................................................................................... 252.2 Types of Natural Ventilation ........................................................................................ 252.2.1 Buoyancy-Driven Ventilation ............................................................................... 262.2.2 Wind-Driven Ventilation ...................................................................................... 282.3 Design Characteristics .................................................................................................. 312.3.1 Building Layout .................................................................................................... 312.3.2 Window Characteristics ........................................................................................ 322.3.3 Thermal Mass........................................................................................................ 332.3.4 Integration of Design Details ................................................................................ 342.3.5 Prototype Building Characteristics ....................................................................... 342.4 Building Performance Evaluation ................................................................................. 352.4.1 Thermal Performance............................................................................................ 362.4.2 Ventilation Performance ....................................................................................... 362.4.3 Energy Performance.............................................................................................. 372.4.4 Long Term Monitoring ......................................................................................... 382.4.5 Short-Term Measurements.................................................................................... 392.4.6 Building Benchmarks............................................................................................ 392.4.7 Characteristics Unique to Naturally Ventilated Buildings.................................... 402.5 Summary ....................................................................................................................... 41Chapter 3.0 Evaluation of Prototype Building: Houghton Hall ...................................... 433.1 Introduction ................................................................................................................... 433.2 Prototype Building: Houghton Hall .............................................................................. 433.3 Monitoring Procedure ................................................................................................... 473.3.1 Site Measurements and Experiments .................................................................... 483.4 Issues with Assessing a Naturally Ventilated Building ................................................ 513.5 Window Airflow Rates ................................................................................................. 523.5.1 Window Airflow Device ....................................................................................... 523.5.2 Airflow Device Measurements and Results .......................................................... 543.6 Prototype Building Monitoring Results ........................................................................ 554
3.6.1 Indoor Environment .............................................................................................. 553.7 Discussion ..................................................................................................................... 663.8 Challenges with Monitoring a Naturally Ventilated Building ...................................... 693.9 Summary ....................................................................................................................... 70Chapter 4.0 Modeling and Visualization Techniques ....................................................... 714.1 Overview of Modeling as a Method ............................................................................. 714.1.1 Full-Scale Modeling.............................................................................................. 724.1.2 Reduced-Scale Modeling ...................................................................................... 734.1.3 Experiment Fluids ................................................................................................. 744.1.4 Buoyancy-Driven Natural Ventilation Modeling ................................................. 744.1.5 Wind-Driven Natural Ventilation Modeling ......................................................... 754.1.6 Combined Buoyancy-Wind Modeling .................................................................. 764.2 Flow Visualization ........................................................................................................ 764.2.1 Principles of Flow Visualization ........................................................................... 774.2.2 Application to Buildings ....................................................................................... 784.2.3 Methods Used ....................................................................................................... 794.3 Summary ....................................................................................................................... 81Chapter 5.0 Dimensional Analysis and Similitude ............................................................ 835.1 Governing Equations .................................................................................................... 835.1.1 Dimensionless Equations and Resulting Parameters ............................................ 845.2 Parameters for Buoyancy-Driven Ventilation .............................................................. 855.3 Similarity Requirements ............................................................................................... 865.3.1 Geometric Similarity ............................................................................................. 865.3.2 Kinematic Similarity ............................................................................................. 875.3.3 Thermal Similarity ................................................................................................ 885.4 Other Issues for Similarity ............................................................................................ 885.5 Characteristic Values .................................................................................................... 895.6 Application of Dimensional Analysis and Similitude .................................................. 895.7 Summary ....................................................................................................................... 91Chapter 6.0 Reduced-Scale Model Methodology and Experiments ................................ 936.1 Introduction ................................................................................................................... 936.2 Model Development...................................................................................................... 936.3 Model Descriptions ....................................................................................................... 946.3.1 Physical Model...................................................................................................... 946.3.2 CFD Model ......................................................................................................... 1006.4 Experimental Equipment and Measurements ............................................................. 1026.4.1 Equipment ........................................................................................................... 1026.4.2 Measurements ..................................................................................................... 1056.5 Experiments ................................................................................................................ 1066.5.1 Buoyancy ............................................................................................................ 1066.5.2 Wind-Assisted ..................................................................................................... 1126.6 Summary ..................................................................................................................... 115Chapter 7.0 Experimental Results .................................................................................... 1177.1 Buoyancy-Driven Ventilation Results ........................................................................ 1197.1.1 Single Heated Zone Case .................................................................................... 1197.1.2 Two Heated Zone Case ....................................................................................... 1265
Page 2 and 3: Thesis Committee:Leon R. Glicksman,
Page 6 and 7: 7.1.3 Full Model Case .............
Page 8 and 9: Figure 41. Wind Direction Data for
Page 10 and 11: List of TablesTable 1. Energy End U
Page 12 and 13: Table 64. Comparison of Dimensionle
Page 15 and 16: Chapter 1.0IntroductionEnergy consu
Page 17 and 18: insulated building envelopes with t
Page 19 and 20: energy usage and efficient design.
Page 21 and 22: Figure 3. European Patent Office Bu
Page 23: selecting boundary conditions) to e
Page 26 and 27: 2.2.1 Buoyancy-Driven VentilationVe
Page 28 and 29: Figure 7. Neutral Pressure Level fo
Page 30 and 31: Combined wind-buoyancy flow is more
Page 32 and 33: design. The depth of natural ventil
Page 34 and 35: of cooling required by 30 percent o
Page 36 and 37: considered when determining how the
Page 38 and 39: environmental conditions are examin
Page 40 and 41: As natural ventilation is prevalent
Page 43 and 44: Chapter 3.0Evaluation of Prototype
Page 45 and 46: Figure 12. Interior Atrium ViewFigu
Page 47 and 48: Table 8. Prototype Building Window
Page 49 and 50: Figure 15. HOBO® H8 Series Tempera
Page 51 and 52: Finally, airflow visualization was
Page 53 and 54: 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
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Radiation was found to have an impa
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height is used for the full-scale b
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6.3 Model Descriptions6.3.1 Physica
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Figure 30. Floor Plan of the Protot
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Figure 31. North Facade of Model wi
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Monitoring data collected from the
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By default, there was no accounting
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40-location card inserted into the
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6.5 ExperimentsTo evaluate the mode
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modified to determine the impact of
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Figure 39. Two Heated Zone ModelWit
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minute interval, the model was assu
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Figure 42. Cross-Section of Wind-Ge
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Table 25. Wind-Assisted Ventilation
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Figure 44. Heaters and Zones for a)
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Height from Floor (m)Height from Fl
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Where V is the outlet velocity, A o
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Table 32. Conduction Heat Loss for
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a) Air Modelb) Water ModelFigure 50
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Height from Floor (m)The temperatur
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Height from Floor (m)In the atrium
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First NorthUpper Window 0.17 m/s -0
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Height from Floor (m)the column at
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Height from Floor (m)Height from Fl
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Height from Floor (m)3.53.02.52.01.
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was less than 12 percent. These val
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Table 39. Variation of Outlet Wind
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temperature of the air was the same
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3.532.521.55m/s4m/s3m/s2m/s1m/s1.5m
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3.532.521.55m/s4m/s3m/s2m/s1m/s1.5m
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The average and exhaust internal bu
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Table 43. Calculated Wind and Buoya
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In the last two lines, for both the
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Figure 80. CFD Simulation of the Te
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uoyancy case the air from the groun
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160
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windows of naturally ventilated bui
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difficult to select the boundary co
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simulations are able to do would al
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Bordass, W.T., A.K.R. Bromley and A
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Linddament, M. 1996. Why CO2? Air I
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172
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MODEL: K20-8SERIAL: 10047RECORDER_I
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2 Boiler-3 50.00 C1 N1 1.0 ON ON OF
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|PW|DESCRIP |KW |KWH|KVA|KVH|------
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2:5 ;day_ofYr17:P30 ;EOT = 0.000075
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2:3136:P30 ;DUM2 = -0.040891:-4.089
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;7:21 ;input location;8:0 ;mulptipl
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;79:P22 ;EXC w/DELAY (only for dela
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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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