Methodology for the Evaluation of Natural Ventilation in ... - Cham
Methodology for the Evaluation of Natural Ventilation in ... - Cham
Methodology for the Evaluation of Natural Ventilation in ... - Cham
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<strong>the</strong> experiments. The variation at <strong>the</strong> column between <strong>the</strong> ground floor and first floor on <strong>the</strong>south side resulted from to two ma<strong>in</strong> factors; <strong>the</strong> addition <strong>of</strong> a rail<strong>in</strong>g at <strong>the</strong> first floor level andsome amount <strong>of</strong> heat transfer between <strong>the</strong> ground floor and <strong>the</strong> first floor.On <strong>the</strong> north half <strong>of</strong> <strong>the</strong> first floor, air exited at both <strong>the</strong> lower and upper w<strong>in</strong>dows <strong>for</strong> all <strong>of</strong> <strong>the</strong>w<strong>in</strong>d speeds used <strong>in</strong> <strong>the</strong> w<strong>in</strong>d-buoyancy cases. At <strong>the</strong> column, a dist<strong>in</strong>ct pattern betweenenter<strong>in</strong>g air velocities above 3 m/s, between 1 and 3 m/s and below 1 m/s was found (Figure 76).At <strong>the</strong> higher w<strong>in</strong>d speeds, <strong>the</strong> temperatures at <strong>the</strong> column had less variation from floor toceil<strong>in</strong>g; however, <strong>for</strong> <strong>the</strong> mid-range <strong>of</strong> w<strong>in</strong>d velocities <strong>the</strong> temperature measured near <strong>the</strong> ceil<strong>in</strong>gwas dist<strong>in</strong>ctly warmer than that <strong>of</strong> <strong>the</strong> lower measurement locations. At <strong>the</strong> mid-range <strong>of</strong> w<strong>in</strong>dspeeds, <strong>the</strong> warm air from <strong>the</strong> atrium entered <strong>the</strong> north half <strong>of</strong> <strong>the</strong> first floor, was fur<strong>the</strong>r heatedby <strong>the</strong> <strong>in</strong>terior loads, and <strong>the</strong>n some <strong>of</strong> <strong>the</strong> air exited back <strong>in</strong>to <strong>the</strong> atrium. At <strong>the</strong> mid-way po<strong>in</strong>tbetween <strong>the</strong> atrium and <strong>the</strong> north façade, <strong>the</strong> air ei<strong>the</strong>r moved toward <strong>the</strong> w<strong>in</strong>dows at <strong>the</strong> northfaçade and exited, or flowed toward <strong>the</strong> atrium and exited at <strong>the</strong> ceil<strong>in</strong>g level <strong>of</strong> <strong>the</strong> first floornorth. At <strong>the</strong> lowest w<strong>in</strong>d velocities, <strong>the</strong> cooler air from <strong>the</strong> atrium entered <strong>in</strong>to <strong>the</strong> first floornorth zone and <strong>the</strong>n was heated due to <strong>the</strong> <strong>in</strong>terior loads and exited back <strong>in</strong>to <strong>the</strong> atrium, as with<strong>the</strong> mid-range air velocities. However, s<strong>in</strong>ce <strong>the</strong>re was less airflow with <strong>the</strong> lower w<strong>in</strong>d speeds,<strong>the</strong> air reached higher temperatures. In <strong>the</strong> heated zone <strong>of</strong> <strong>the</strong> north half <strong>of</strong> <strong>the</strong> first floor adist<strong>in</strong>ct temperature pattern arose with w<strong>in</strong>d velocities less than 4 m/s (Figure 77). There wassome amount <strong>of</strong> heat loss through <strong>the</strong> floor <strong>of</strong> this zone, though a layer <strong>of</strong> <strong>in</strong>sulation board andadditional R-13 batt-<strong>in</strong>sulation was <strong>in</strong>stalled. The temperature <strong>of</strong> <strong>the</strong> air <strong>in</strong>creases due to <strong>the</strong>heaters and rises toward <strong>the</strong> ceil<strong>in</strong>g. The warm air that exited back <strong>in</strong>to <strong>the</strong> atrium at ceil<strong>in</strong>glevel was seen <strong>in</strong> <strong>the</strong> temperature measurements from <strong>the</strong> heated zone.Figure 69. Temperature Distribution <strong>for</strong> Comb<strong>in</strong>ed W<strong>in</strong>d-Buoyancy Driven Flow at 0.5 m/sIn <strong>the</strong> second floor, <strong>the</strong> temperature distribution varied noticeably with <strong>the</strong> <strong>in</strong>let w<strong>in</strong>d speeds at<strong>the</strong> column (Figure 78). At higher w<strong>in</strong>d speeds, 4-5 m/s, <strong>the</strong> temperature was uni<strong>for</strong>m from floorto ceil<strong>in</strong>g. However, at velocities less than 4 m/s, <strong>the</strong> temperature close to <strong>the</strong> ceil<strong>in</strong>g roseconsiderably. For <strong>the</strong> lower two measurement locations at w<strong>in</strong>d speeds at or below 1.5 m/s, <strong>the</strong>143