Document V0ED5m2JRw6anV0Jw49LYdnp

186 CHAPTER 13 1960 Guide Table 3 .... Outdoor Air Requirements* AppOcnfoa Smoking floor c "S if MMmum* Minimum* Apartment Banking space............... Barber shoos................. Beauty panora.............. Occasional__ Considerable Occasional___ 20 20 10 15 10 10 10 m 10 7H Brokers' board rooms.. Very heavy... 50 40 Corridore (supply or 20 25 ru 5 Directors' rooms........... Extreme......... 50 30 Drug stores*.................. Five and Ten Cent Funeral parlors............. Considerable. None............... 10 10 7W 10 7H 7j| 7J4 0.05 o.io i!o Hospitals Operating rooms1*.. None............... 30 Kitchens y 30 25 10 Laboratories*................. Some............... 20 15 Meeting rooms.............. Very heavy... 50 Offices Private........................ Restaurants Cafeteria*................... Dining room*............. Considerable. Considerable . Considerable . 25 30 12 15 30 10 15 25 10 12 Schoolrooms* ......... ... None............... Toilets* (exhaust)........ 10 7M IS 7\i 5 10 2.0 0.33 0.33 4.0 2.0 1.25 0.25 0.25 2.0 * Taken trod pwwrnit Hsy practice. b Tfeii it fufl air. * When minimum fe uad, take the larger of the two- * See beat codes which me; govern. * Me; be governed by ext*net. 1 Ibj be cr*nwd by epttxa) *oaire* ol rontemhmtioa or load codes. * AH oatride sir reoomnmnded to overcome explosion heserd ot eneethntioe. See Natioml Board ofFin Underwriter*' PampUot No. 64. (Continued from p. 179) north) are given in Table 4 for the two types of atmospheres. These are based upon observations made on cloudless days in Cleveland over a period of several summers. Since less ex tensive data were available for industrial atmospheres, there is more uncertainty regarding these values. In both instances, the values include an unknown amount of ground reflection, which may be expected to vary with location. It should be noted that clouds which do not obscure the sun tend to increase diffuse radiation values. Nearby buildings may reduce diffuse irradiation by partial shading. Calculation Tables The irradiation of a surface by the sun is the product of Ip, the direct normal radiation (see Table 4), and the cosine K of the incident angle 6. Forhorixontal surfaces, the cosine K equals the sine of the solar altitude- For vertical walla, K is a function of the solar altitude 0 and the wall solar azimuth y% thus K - cos 8 -- cos 0 cos y (1) These three angles are defined in fig. 1. Values of K are given in Table 5 and values of 0 and y are given in Table 6 for 18-deg north declination (August 1). To compute K values for orientations other than - those given in Table 5, third *nglw the solar azimuth, is required. In this discussion, 4> will be measured east from south in the morning, and west from south in the afternoon. Hence, <f> values are equal to 90 deg minus the y values for an east or west facing wall, except when Table 6 shows the south walls to be in the shade. In this case <0 equals 90 + y, that is, b is greater than 90 deg. The wall azimuth <0 is the angle, measured east from south to the perpendicular to the wall for walls which have an easterly component, and west from south for those having a westerly component. For example, ^ for a wall facing north east is 135 deg. The wall solar azimuth 7 may be found according to the following schedule: For walls facing east of south: For walls facing west of south: y -- * -- + *.m. 7 TM b + i> a.m. 7 = * 4- ^ p-m. 7 = <(> -- ? p.m. Treat negative values of 7 as il they were positive. If 7 is greater than 90 deg, the wall is in the shade. Values of K for other seasons and latitudes may be found in the literature,7 or may be computed from data given in Hydrographic Office Bulletin No. 214, Tables of Computed Altitude and Azimuth1 and the Ephemeris of the Sun.* Table 7 shows the variation of solar declination during the months ordinarily requiring cooling. Example 1: Find the solar azimuth 4 at 6:30 p.m. at 40-deg north latitude on August 1. Solution: From Table 6 in the column of 7 for a wall facing west ^ for 6:00 p.m. is 90 + 14 -- 104 deg, and at 7:00 p.m. is 90 + 24 TM 114 deg. By interpolation, 4 for 6:30 pun. is 109 deg west of south (at 5:30 a.m. 4 would be 109 deg east of south). Example t: Find K for a wall facing IS deg east of south at 10:00 a.m. on August 1 at 50-deg north latitude. Solution: The wall azimuth is 18 deg. The solar azimuth is 48 deg east (Table 6). The wall solar azimuth is 48 -- 18 or 30 . deg. From Table 6,0 is 50 deg. Then K " cos 0 cos 7 * cos 50 X cos 30 = 0.643 X 0.866 = 0-557. Example 3: Find K for the wall in Example t at 3:00 p.m. Solution: The solar azimuth is 65 deg west. The wall solar azimuth is therefore 65 + 18 83 deg- The angle 0 is 42 deg. K = cos 42 X cos S3 = 0.743 X 0.122 ~ 0.091. Example 4: Find the total solar irradiation for the wall for the conditions of Example t. Solution: Use clear atmosphere solar intensities. At 50~deg altitude, the direct normal radiation is 273 Btu per (hr) (sq ft). Then, lo - K X IDo - 0.557 X 273 152.0 Btu per (hr) (sq ft). Cooling Load 187 Table 4 .... Values of /, Direct Solar Radiation Received at Normal Incidence at the Earth's Surface, and Values of fa, Diffuse or Sky Solar Radiation, Received by Variously Oriented Surfaces fitu per (hour) {sgoaf* fool) SoJor Altitude 0, Degree* Direct* normal radiation AM - 1 5 10 15 20 25 67 123 166 197 218 For Otar Atmoophere* Diffusa or sky radationb*' N E s w Horn. 6 11 4 4 11 20 8 7 14 27 11 10 15 32 13 12 16 35 15 13 7 14 19 23 26 Direct* normal radiation 34 58 80 .103 121 For Industrial Atmosphere* Diffuse or sky rad*afionb** NE S W Hertz. 4 11 53 8 22 9 7 11 28 13 9 13 36 17 12 16 43 21 16 9 18 24 31 38 30 235 17 36 17 15 28 136 18 47 24 18 44 35 248 17 36 19 16 30 . 148 19 50 27 21 48 40 258 18 36 21 17 31 158 20 50 30 23 52 45 266 19 35 23 18 32 165 21 49 31 25 55 50 273 19 33 25 19 33 172 22 47 34 27 58 60 283 21 28 27 21 34 181 22 41 37 30 63 _ _70 289 22 23 29 23 35 188 22 34 41 34 69 80 292 -- -- -- -- 195 90 294 -- -- -- -- -- 200 -- -- -- -- -- r PM -- Nw S E Hortz. Nw $ Horiz. * Moon'** proposed standard foreea level. 30 cam preripttable water vapor, J00 dost portide* per cu on, Mmm Hz partial prMsure ot <noaa. b For 40 deg north latitude on about Adjust 1. Baaed on elan lkiiiabv ASHRAE Laboratory at CWuBland on riondla-- day* dimnywhiehtheahaamm) normal Jypprwirim*H tlw 00*10*1 vaJoes 4 Derived from teeoauneaded **--'f" *ol-*ir temperatures* for New York City for a haritontal surfaee with absorptivity of 1J). latitude 30 Deg north 40 Deg north 50 Deg north Table 5 .... Values of K, the Cosme of the Incident Angle, for Variously Oriented Walls and a Horizontal Surface Competed for IS Otg Oecfinetioe, North (August 1) Sun Time Corine K of (he Incident Angle AM -- 1 6 a.m. 7 8 9 6 p.m. 5 4 3 10 2 11 x 12. N 0.287 0.144 0.030 NE 0.862 0.752 0.604 0.427 0.234 0.039 0.952 0.919 0.824 0.672 0.476 0.246 0.000 SE 0.484 0.548 0.561 0.524 0.438 0.310 0.147 S 0.068 0.144 0.192 0.208 5 a.m. 7 p.m. 66 75 84 93 10 2 11 1 12 0.406 0.237 0.079 0.934 0.840 0.705 0.533 0.337 0.129 0.914 0.951 0.919 0.824 0.673 0.475 0.246 0.000 0.358 0.505 0.594 0.631 0.614 0.542 0.424 0.265 0.069 0.196 0.292 0.354 0.375 5 a.m. 7 p.m. 66 75 84 0.385 0.199 0.010 0.922 0.813 0.656 0.465 0.920 0.951 0.918 0.824 0.378 0.532 0.643 0.700 0.166 93 10 2 11 1 12 0.252 0.030 0.673 0.475 0.247 0.000 0.699 0.642 0.532 0.375 0.316 0.433 0.505 0.530 t PM -- N NW W SW S SW 0.147 0.076 0.285 0.183 0.375 SE Horiz. 0.1S6 0.367 0.566 0.737 0.866 0.951 0.978 0.009 0.199 0.391 0.566 0.713 0.829 0.903 0.927 0.078 0.233 0.399 0.545 0.669 0.766 0.829 0.848 Horiz-