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

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and experiments used in evaluating the performance of the prototype building and for evaluatingthe reduced-scale modeling technique are presented in the following sections.3.3.1 Site Measurements and ExperimentsThe analysis of Houghton Hall was completed through a combination of long-term and shorttermmeasurements, with some experimental work to focus on specific areas. Long-termmonitoring of the building was meant to be unobtrusive and record building characteristics atfifteen-minute intervals over the period of twelve months. Short-term measurements were takenduring site visits primarily during the spring, summer, and fall months. Short-term measurementswere not taken during the winter months because the building was closed up, and naturalventilation system was not active during that period. However, data continued to be gathered aspart of the whole building performance analysis.3.3.1.1 Temperature MeasurementsOne of the more important things monitored was the interior temperature, as this is a firstindication as to the performance of any building. If the internal temperature is outside of thecomfort range, productivity can deteriorate. In addition to temperature, the data logging devicesalso recorded relative humidity levels, which can be another factor for naturally ventilatedbuildings, as they do not have means to either humidify or dehumidify the entering air. For longtermtemperature and humidity monitoring, HOBO® H8 Series compact temperature and relativehumidity data loggers were used throughout the building. Most of the data loggers were locatedat desk height, approximately 1.2 meters above the floor. An additional series of four dataloggers was installed in each occupied floor area at four different heights, at the floor level, 0.76m above the floor, 1.76 m above the floor, and 2.54 m above the floor, to obtain an initialdetermination of stratification within the occupied zone. Four other data loggers were placedaround the atrium at each floor level to determine the amount of stratification that occurredwithin that space. The location of the HOBO® data loggers for a sample half-floor plate isshown in Figure 15. The data loggers were placed between windows, to avoid being in the directairflow from the window. The data loggers located at the atrium were attached at the floor levelat the ledge of the atrium.48
Figure 15. HOBO® H8 Series Temperature and Relative Humidity Data Logger Locations in aSample Half Floor Area. The black squares represent the thermocouple locations. This layout isduplicated in each of the four half floor plates.External conditions were recorded to provide data both on the conditions to which the buildingwas exposed and on the entering air properties. As there was a substantial amount of glazing onthe façades of the building (46 percent of the total façade area) solar radiation was an importantcondition to be monitored. Not only outside air temperature, but also humidity, barometricpressure, direct and diffuse solar radiation, and wind speed were recorded. A Campbell Scientificweather station using a CR10X data recorder was mounted on the roof of the prototype building.The weather station was located so that it would not be influenced by exhaust air from the stackvents, nor sheltered from the outside elements. The outside temperature gauge was housed in awhite plastic device so that it was not subject to erroneous readings due to solar gain, rain orwind. The rotating vane cup anemometer was located 1 meter above the atrium roofline,approximately 1.5 meters away from any stack vent. The program used to record the datameasured the gusting or peak wind speed over the fifteen-minute interval as well as the averagevalue over the same interval. Both direct and diffuse solar radiation was measured using theweather station. The solar radiation data was recorded by using one pyranometer for thehorizontal solar radiation, and another pyranometer along with a shadow-band device thatrecorded diffuse solar radiation. The shadow-band rotated to shade the direct solar radiation tothe pyranometer, while recording the diffuse solar radiation.3.3.1.2 Air Quality MeasurementsEvaluating the ventilation performance of naturally ventilated buildings is more complex thanthe evaluation of a mechanically-conditioned building. The environment within the naturallyventilated building is affected not only by changes in the outside environment, e.g. wind speedand direction, but also by occupant behavior. In the prototype building, the main windows areoccupant controlled and can be anywhere from cracked open to fully opened, 0.24 meters in thehorizontal direction. The window geometry was an additional factor that had to be addressed in49
Page 2 and 3: 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: Table 8. Prototype Building Window
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 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
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
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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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