Document QJ4aBgNj9qgGgjxxJvJ8k99BR

ofAmerican Society Heating and Ventilating Engineers GmDiTlgjjl | ----^--------- Chapter 8--Cooling Load 1 SUN 1 Si and thickness of the glass and the angle between the rays of the character ,gs The temperature of the glass is raised by the sunlight ana ^.g jieat ;s then delivered to the air on the two sides Of absorbed nea nrooort;on to the difference between glass and air temthe glass in p f Oh_i < a-" c 91 0 i .. CE 3 </> ---------- (/ ------ --^ > sy / /- '/ / c V 1 \. d i \ \' ( tm- _____ L 3 r/ y-- y O vD ,, y tests indicated that a single pane of double strength ThCn 127 in thick absorbs approximately 11 per cent of the solar glass O t jng through it when the impingement is normal. For Ration P of8irnp;ngement, the glass retards percentages of the total smaucr g approximately. in proportion to the sine of the angle. Other experiments4 indicate a glass absorption of 16.7 per cent for one I- pane of glass and 37.5 per cent for two Jfc-in. panes separated by a 1%-in. The amount of solar radiation delivered to an unshaded glass surface maa*yy be obtained the solar from the curves in Fig. radiation incident to 1. For surfaces other the glass must be than those calculated. fTmirickson and Walker6 have shown how this may be done if the wall faces some direction other than east, west, or south. They have also shown how to calculate the net glass area on which the solar radiation impinges when the glass is partly shaded by the frame or wall. The values from Fig. 1 must be used only for the net glass area on which the sun shines. Recent tests at the A.S.H.V.E. Research Laboratory6 have determined the percentage of heat from solar radiation actually delivered to a room with bare windows and with various types of outdoor and indoor shading. The data in Table 4 are taken from these tests. l \ VV \ \ _J < a Nw -i < H l&l zu . N0 k5 . Ov> < f/ 1 \ \ \w hi z D * Table 4. Solar Radiation Transmitted through Bare and Shaded Windows Per Cent Delivered to Room 97 28 45 68 58 22 V \ \ v< N The percentage figures in this table were obtained by dividing the total amount of heat actually entering through the shaded window by the total amount of heat calculated to enter through a bare window (solar radiation plus glass transmission based on observed outside glass tern-, perature). For bare windows on which the sun shines, the transmission of heat from outside air to glass is small as the glass temperature is raised by the solar radiation absorbed. Therefore, in calculating the total heat gain through windows on the sunny sides of buildings, it is sufficiently accurate to figure the total cooling load due to the window, as the solar radiation times the proper factor from Table 4, and to neglect the heat Oo o <o O O' OO o *o O o anOH H3d Id OS H3d niQ ^or Comfort as Affected by Solar Radiation, by G. A. Hendrickson and J. H. Walker, kJt*8 November, 1932, and The Determination of Sun Effect on Summer Cooling Loads, - ^ (CaIa* Wcn"nc^8on and J. H. Walker, Heating and Ventilating, June, 1933. Radiation Through Bare and Shaded Windows, by F. C. Houghten, Carl Gutberlet. j.ir. clackshaw (A.S.H.V.E. Journal Section, Heating, Piping and Air Conditioning, February, 1934). 151