Document evYE2L4ORpMZKzEOmEOgB3V9

316 CHAPTER 13 1958 Guide Table 18. Description of Glass Block Patterns A- Outdoor surface 'A P ^ ^ bSc 6 D-Indoor surface Is BK- E- Cavity partition Hollow Glass Block User fob Vebtical Walls Type I --Smooth Face Type IV--Light Diffusing A, D: Smooth A, D: Close pitch deep horizontal B: Wide vertical ribs or flutes corrugations C: Wide horizontal ribs or flutes B, C: Vertical light diffusing prisms E: None E: None Type II --Semi-Light Diffusing A, D: Narrow vertical ribs or flutes B, C: Etched or stippled Type IVA--Light Diffusing Same as IV except tions vertical corruga E: None Type V --Light Directing A, D: Close pitch deep vertical cor Type III--Light Diffusing rugations A, D: Narrow vertical ribs or flutes B, C: Horizontal light directing B, C: Etched or stippled prisms E: Glass fiber screen E: None Hollow Glass Block Used for Horizontal Skylights Type VI--Light Directing (skylight) A: Smooth surface B: Light-directing prisms C, D: Light-diffusing surface E: Clear glass fiber screen Type VII--Light diffusing (skylight) A: Smooth surface B, C: Stippled surface D: Narrow-ribbed surface E: Green-tinted glass fiber screen same that a single table suffices. Note, however, that corrections must be made for certain hours for east and west facing walls of some patterns. Tables 22 and 23 give instantaneous heat gain values for two types of glass block designed for use in skylights. The Type VI block is 10% x 10% in. and the Type VII block 12 x 12 in. It should be noted that the data for Type VI glass block in Tables 22 and 23 are for panels as assembled. Since the manner of mounting this type of block is standard the ratio of glass area to opaque area is virtually constant from one skylight to another. The Type VII glass block may be mounted on a wide range of center-to-center distances. The opaque por tion of the assembly should be considered independent of the glass block. See Reference 24 for more complete information. These tables are based upon the solar intensity values for a clear atmos phere as given in Table 4. For solar energy transmittance data refer to References 21 and 24. The values of convection arid radiation gain are based on values of 80 F for indoor air temperature, a maximum outdoor air temperature of 95 F and upon experimentally determined values of solar energy and tempera ture difference between the two faces. Indoor and outdoor convection and radiation heat transfer values are the same as those used for common win Cooling Load 317 Table 19. Instantaneous Rate of Heat Gain Due to Transmitted Direct and Diffuse Solar Radiation by Unshaded Walls of 8-in. Hollow Glass Block of Type I Pattern For Clear Atmospheres and 18 Deg Declination, North (August 1) Note: For toted instantaneous heat gain add these values to Table St values u o Sun Time Instantaneous Heat Gain in Btu peb (hb) (sq ft) AM-> < , 4- N NE E SE s SW W NW B & ZO oH eo Z O a Q o z o Qa ' o 67 a.m. 89 10 11 12 5 a.m. 6 7 8 9 10 11 12 56 a.m. 7 8 9 10 11 12 6 p.ra. 5 4 3 2 1 7 p.m. 6 5 4 3 2 1 7 p.m. 6 5 4 3 2 1 4 45 55 12 2 2 2 2 55 5 59 42 25 94 29 94 38 59 34 4 5 6 33 44 55 3 4 5 6 12 6 .8 8n 6 3 5 50 4 54 5 34 27 24 9 12 13 . 10 78 9 30 67 17 98 36 90 47 0 2 4 5 66 6 76 6 8 7 .6 00 22 44 44 0 2 4 4 5 18 59 47 10 5 5 5 6 8 29 35 15 56 6 6 6 13 22 18 76 6 6 6 6 13 17 13 6 6 4 28 27 4 1 1 1 1 5 53 77 22 3 2 2 2 4 44 101 44 4 4 4 4 4 26 86 57 7 4 4 4 5 12 57 60 16 55 5 5 6 29 54 25 65 5 6 6 14 34 32 10 6 6 6 6 6 20 34 20 6 6 PtM-> N NW W SW S SE E NE dow glass. Table 24 gives corrections to be applied for other design tem peratures. Example 9: Find the total instantaneous heat gain through an east wall of s-in. hollow glass block of Type V pattern at 8 a.m. and 50 deg north latitude. The design temperatures are 80 F indoors and 95 F maximum outdoor dry-bulb, clear atmosphere. Solution: The gain due to transmitted solar radiation is found from Table 19 tor type I pattern. The factor for Type V is found from Table 20. The convection and radiation gain is found from Table 21 (note the footnote). The total instantaneous heat gain is, from Equation 2a, 9 = 86 X 0.65 + 26 X 1.4 = 92.3 Btu per (hr)(sq ft). Effect of Deviations from Design Conditions h ik ?e *n^oor temperature differs from 80 F, or the design outdoor dryouib temperature differs from 95 F, corrections can be made, to the conveclon and radiation gain values for flat glass, rolled figured glass, and glass Diock according to the schedule in Table 24. .?'^le effect of the humid industrial type atmosphere is to cause a con- thp6rab e re^uct*on in heat gain, if all factors except solar intensity remain j same- Reference 22 gives heat gain values for four orientations at 40 bio k h ktitude on August 1 for several types of flat glass and glass data ^'ll S0*ar intensities typical of humid industrial atmospheres. These for thrT the following approximate reductions, based on total gain me day, can be expected: 20 percent for all types of glass and glass