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

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12:00 AM2:00 AM4:00 AM6:00 AM8:00 AM10:00 AM12:00 PM2:00 PM4:00 PM6:00 PM8:00 PM10:00 PMCarbon Dioxide (PPM)900AVERAGE SummerAVERAGE Winter800700600500400Outside CO2 Level3002001000Figure 22. Internal Building Carbon Dioxide Levels: Summer versus Winter ConditionsAlthough, each method proved useful for comparison and for evaluating the air exchange rate,there was a certain amount of uncertainty in each of the methods used. The hot-wireanemometer measures air velocity in a single direction, and cannot account for flow that is notperpendicular to the wire. Additionally, the bag device had to be constructed to ensure that anaccurate volume flow rate was being measured. The bag device was useful in providing a betteridea of the volume of air entering the building, but could not be used for the upper windows, orthe exhaust windows, due to restrictions in access to them. A single volume flow rate wasmeasured, as there was only one bag device built for use in measuring volume flow rate. Thecarbon dioxide data had a degree of uncertainty due to the location of the device. There is somebuoyancy flow in the building, and locating the carbon dioxide sensor on the upper floor couldcause elevated measurements of the levels of carbon dioxide for the building. Finally, with theenergy balance, data were used for a specific period of time, even though the building hastransient effects due to the thermal mass, changes in the exterior environment such as clouds orwind gusts, and consistency of the state of the internal loads.The airflow visualization techniques employed provided insight into the interaction of theoccupied office spaces with the atrium. As the ground floor normally had the coolesttemperature, warm air from the occupied zone on the ground floor slowly moved toward theatrium. However, on the first floor, the air in the atrium was cooler than the air in the occupiedspaces on the first floor, so the air flowed from the atrium into the office space, and then exitedat the ceiling level of the office space back into the atrium. At the second floor occupied zone,the airflow tended to either move from the atrium through the second floor space and then out of64
the windows on the second floor, or from the second floor space into the atrium and then risetoward the stack vents where the air was exhausted to the outside. Figure 23 illustrates thisairflow behavior. Smoke pencils verified the detailed flow patterns, particularly those at theconnection of the atrium and office space. These airflow patterns did not seem intuitive when theexperiments were carried out, but similar airflow patterns were observed when modeled using acomputational fluid dynamics program.Figure 23. Airflow Patterns Observed in Prototype Building Field Measurements3.6.1.3 Energy UsageThe energy usage analysis was divided by sub-systems into two separate day types; occupied(weekday) and unoccupied (weekend). Electric energy usage was also compared by season todetermine if usage patterns changed due to internal and external environment. It was found thatthere was no significant change due to the season with the electric energy usage within thebuilding. The occupant schedule was observed to stay regular throughout the year as peoplebegan arriving for the day at 8:00 am and for the most part left by 6:00 pm. From the usagetrends and known information about the number of people within each office space, it wasdetermined that the energy usage depended on occupant density; the more people in a half flooroffice area, the higher the energy usage. The number of occupants within an office space has adirect correlation to the number of computers, monitors, and printers within a given space,potentially explaining this trend. This is shown in Table 16. It should be noted that the GroundFloor South energy usage was determined by subtracting the computer server room energyconsumption base load that it contributed to the measured power draw for the Ground Floor area.The second floor north had significantly more personal printers than either of the other zones,causing a higher peak energy usage per person.65
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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
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
Page 55 and 56: Table 10. Window Bag Device Measure
Page 57 and 58: Mon 7-21Tue 7-22Wed 7-23Thu 7-24Fri
Page 59 and 60: 12:00 AM1:00 AM2:00 AM3:00 AM4:00 A
Page 61 and 62: 27-Jul27-Jul28-Jul28-Jul29-Jul30-Ju
Page 63: A range of air exchange rates was f
Page 67 and 68: Total Electric (kWh/m2)Total Gas (k
Page 69 and 70: movement, Houghton Hall has much le
Page 71 and 72: Chapter 4.0Modeling and Visualizati
Page 73 and 74: for future design of similar type b
Page 75 and 76: lower and upper openings and natura
Page 77 and 78: the acceptable diffusion rate, or
Page 79 and 80: applications involving full-scale b
Page 81 and 82: digital camera with both manually o
Page 83 and 84: Chapter 5.0Dimensional Analysis and
Page 85 and 86: u oHgHT2uocu Hpo1Re Ar1Re Pr(5.7)(5
Page 87 and 88: 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
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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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