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

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Window plastic, or the material that is used to protect against cold drafts from leaky windowsduring the winter, was used. Several other thin, pliable plastic sheets were tried, but the windowplastic was found to be durable, yet supple enough to use for the airflow device. The plastic wasthen taped together to form a rectangular volume that would fit the frame. A release flap wasincorporated into the bag portion of the device, so that if there were sudden gusts of wind, thedevice could remain in place and not be destroyed by the sudden surge of air in the limitedvolume bag.3.5.2 Airflow Device Measurements and ResultsOnce constructed, the airflow device was tested out on the awning-type windows at the prototypebuilding. Previously, air velocity measurements had been recorded in the horizontal plane of thewindow, ignoring the vertical side pieces. With the bag device, velocity measurements weretaken concurrently with air volume flow rates, so that the previously recorded air velocitymeasurements could be correlated to a volume flow rate. Measurements were taken during alow-wind day at the prototype building, with few gusts of wind.Table 9. Window Bag Device CharacteristicsMeasured Dimension of Bag DeviceValueLength of Frame1.0 metersWidth of Frame1.2 metersHorizontal Opening Area of Window1.2 square metersDepth of Bag1.3 metersVolume 1.5 m 3The effective area was calculated by taking into account the volume flow rate Q (based on thewindow bag device measurements), recorded air velocity measurements V in the horizontalplane, and the total vertical cut-out area A of the awning window. This is represented by:Q V AEff(3.18)where Eff is the effectiveness of the window opening. For the experiments, the time recordedwas for the bag device to inflate 100 percent. The exception was Trial 8, in which the bag onlyinflated a third of the way. The resulting measurements for both the air velocity and time for thewindow bag device to inflate are presented in Table 10. This calculated effective area of 30percent was then used in the modeling efforts presented in later chapters.54
Table 10. Window Bag Device Measurements and Resulting Flow Rates and EffectivenessCalculationsTime(sec)Air Velocity(m/s)Volume ofAir (m 3 )Volume flowrate (m 3 /s)EffectiveOpening (m 2 )Effectivenessof WindowTrial 1 7 0.6 1.5 0.2143 0.3571 29.7%Trial 2 10 0.4 1.5 0.1500 0.3750 31.2%Trial 3 8 0.5 1.5 0.1875 0.3750 31.2%Trial 4 6 0.7 1.5 0.2500 0.3571 29.7%Trial 5 8 0.5 1.5 0.1875 0.3750 31.2%Trial 6 7 0.6 1.5 0.2143 0.3571 29.7%Trial 7 10 0.4 1.5 0.1500 0.3750 31.2%Trial 8* 14 0.1 0.5 0.1071 0.3571 29.7%Average 8.75 0.475 1.5 0.1826 0.3661 30.5%*bag device inflated only 1/3 of the way3.6 Prototype Building Monitoring ResultsThe data were analyzed to determine the seasonal and annual performance of the prototypebuilding after the eighteen-month monitoring period from May 2003 to October 2004. Thissection presents the resulting data by area, internal environment and energy usage.3.6.1 Indoor EnvironmentThe data evaluating the indoor environment were collected and analyzed by season. The focuswas on the shoulder months, spring and fall, and the summer months, as these periods had themost variation due to the operation of the building in response to the internal and externalcondition requirements. However, some winter data are presented for comparison of indoorconditions.3.6.1.1 TemperaturesThe average of all of the temperature data loggers at each fifteen minute interval was used tocalculate an average internal building temperature for both a sample summer period and winterperiod. The summer data provide information on the ability of the building to keep the interiortemperatures lower than the outside, even during extreme heat. The winter data show thefluctuation of internal temperatures during occupied hours, with the heaters in use primarilyduring occupied hours, but with a minimum set point to avoid frost.Error! Reference source not found.Figure 17 and Figure 18 show the summer and winterinternal building temperatures compared to the external temperatures. Through monitoring of thetemperature within the office spaces in Houghton Hall, it was determined that the temperaturevaried little, between 1 and 2 degrees C, across each half floor, but more significantly betweenfloor-levels. Sample data from occupied hours during a day in August 2003 are presented inTable 11 for two points on the ground floor (GF-1, GF-2), First Floor South (FFS-1, FFS-2),First Floor North (FFN-1, FFN-2), and Second Floor (SF-1, SF-2). For the most part the groundfloor had the coolest temperatures, year-round. The second floor was observed to have the55
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Thesis Committee:Leon R. Glicksman,
Page 4 and 5: Table of ContentsTable of Contents
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: only is the airflow almost never at
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 and 64: A range of air exchange rates was f
Page 65 and 66: the windows on the second floor, or
Page 67 and 68: Total Electric (kWh/m2)Total Gas (k
Page 69 and 70: movement, Houghton Hall has much le
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Page 75 and 76: lower and upper openings and natura
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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
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Page 98 and 99: Figure 31. North Facade of Model wi
Page 100 and 101: Monitoring data collected from the
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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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