Book - School of Science and Technology

82 The building in summerTable 3.6 ContinuedDateOrientationSolar cooling load at stated sun time …W m 2 †0730 0830 0930 1030 1130 1230 1330 1430 1530 1630 1730SE 272 314 328 311 264 195 90 123 127 116 107S 74 77 239 209 240 248 229 187 73 137 79SW 85 97 106 117 198 220 277 309 309 283 229W 107 119 128 136 140 148 276 289 345 369 350NW 106 117 127 134 139 141 142 152 284 264 291Table 3.7 Correction factors for internal shading (applying to Table 3.6 only)Glazing configuration(inside to outside)Correction factor for Glazing configurationstated building response (inside to outside)Correction factor forstated building responseFast Slow Fast SlowBlind/clear 1.00 1.03 Blind/low-E/clear 0.92 0.92Blind/reflecting 0.69 0.71 Blind/low-E/reflecting 0.59 0.60Blind/absorbing 0.75 0.76 Blind/low-E/absorbing 0.63 0.62Blind/clear/clear 0.95 0.94 Blind/low-E/clear/clear 0.84 0.83Blind/clear/reflecting 0.62 0.62 Blind/low-E/clear/reflecting 0.53 0.53Blind/clear/absorbing 0.66 0.66 Blind/low-E/clear/absorbing 0.55 0.55Blind/clear/clear/clear 0.86 0.86Blind/clear/clear/reflecting 0.55 0.55Blind/clear/clear/absorbing 0.57 0.56Additional factor for airtemperature control0.91 0.89and west facades but that their influence there upon the peak cooling load to individualspaces may not be large. In terms of the maximum cooling load in a whole building,however, such fins may contribute to a reduction.Horizontal projections formed by outward extensions to floor slabs above windowsmay make a contribution if formed on the southerly facades, south east through to southwest, as shown in Figure 3.8. The effect of such shading, for an air-conditioned commercialbuilding, may be expressed also in terms of annual energy expended in cooling, aspredicted for a south facing room using a variety of shading methods and dimensions, andlisted in Table 3.8.The diurnal cycle of the sun's motion subjects the various faces of a building to apattern of shading which changes continuously and, as has been noted previously, if abuilding has wings forming an L or a T or some other more confused shape, the shadingpattern may become complicated. In consequence of demands for detailed data, computermodelling programs have been produced and the form of output from one such isillustrated in Figure 3.9.