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HEATINC VENTILATINC AIR CONDITIONING CUIDE 1943 perature reaching a maximum of 93 F as shown by the temperature curve in Fig. 3 and an indoor temperature of 78 F and 50 per cent relative humidity. The heat flow shown in Figs. 2 and 3 is a combination of normal trans mission and solar radiation transmission and is the total heat flow through the wall or roof. Due to the heat capacity of walls and roofs there is a time lag6 in the transmission of heat through them as shown by the curves*. For the types of construction covered in Figs. 2 and 3 and for the con ditions indicated, the heat flow through the inside surface at any given time can be read directly. For other types of construction, the curves may be used as a guide in estimating the heat flow. The time lag for Fig. 3. Relation Between Time and Heat Flow Through the Inside Surface.of ' Walls of Different Construction and Owentation on a 93 F Design ' Day with 90 per cent of Design Solar Radiation Wall* BE. BS, BW and BN--12 in. solid biick and poster facing east, south;west and north respectively. Walls TE, TS, TW and TN--4 in. brick veneer, 8 n. tile and plaster facing east, south,' west and north respectively. Walls FE, FS and FW--4 in. brick veneer, building paper, % in., matched sheathing, 2 x 4 in. studs, ;metal lath and plaster facing east;;south and west.respectively. ., ; > -. ,, _ - other types of construction is included, in Table 6 which was' jjtepared by the A.S.H.V.E. Laboratory from data.collected by. it arid by other authorities. Solar Radiation Transmitted Through Glass b Windows present a problem some\yht different from that of opaque walls, because, they permit a large; percentage ofsthe solar energy to pass .through. A small amount is reflected and a portion is. absorbed by'die glass: The amount absorbed depends upon the character and thickness of'the glass and the angle between it'and the sun's rays. The;temperature of the glass is raised by the absorbed heat and this heat is then- delivered *Loc. Cit. Note 2. T54 CHAPTER 7. COOLING LOAD Table 6. Time Lag in Transmission of. Solar Radiation t Through Walls and Roofs Type and Thickness of Wall or Roof Time Lac, Hours 1-in. yellow pine horizontal roof, water proofing, smooth black finish-------2-in. yellow pine horizontal roof, water proofing, smooth black finish..... -- 4-in. reinforced clay tile horizontal roof, water proofing, slag finish---------2-in. gypsum horizontal roof, water proofing, slag finish---- -------------------Slate and slaters felt on 2)4 in. tongue and grooved yellow pine, sloped roof 4-in. gypsum horizontal roof, water proofing, slag finish---- :------:------------6-in. concrete horizontal roof, water proofing, slag finish------------------------1-in. concrete, 4-in. cinders, l}^-in. concrete, water proofing, smooth black finish________________________ ___________ _____ _________ :------Wood siding, 1-in. sheathing, 2x4 studs, lath and plaster--------- --- ------Wood siding, 1-in. sheathing, 2x4 studs (studding space filled with insula tion) lath and plaster___ 4-in. brick, Lin. sheathing, 2x4 studs, lath and plaster.------------------------ 4-in. brick, 8-in. tile and plaster...........--1...... ...................... ...... ............... 13-in. brick, plastered:---------------------------------------------------.................... 9-in. brick, 3?4-m- tile, 5)4-in. air space, 3i!-in. tile and lM-in. plaster.... 1 m 2H 2K 2H 4)4 5 8 2 5 7 10)4 12 16 to the air on each side in proportion to the difference between the glass and air temperatures6. The A.S.H.V.E. tests7 indicate that a single pane of.double strength glass 0.127 in. thick absorbs approximately 11 per cent of the. solar radiation passing through it when the impingement is normal. For smaller angles of impingement, the glass retards percentages of the total radiant energy approximately in proportion to the sine of the angle. The amount of solar radiation delivered to an unshaded glass surface may be obtained from Tables 2, 3, 4 or 5. These values must be used only for the net glass area on which the sun shines and not the entire glass area. Tests at the A.S.H.V.E. Research Laboratory8 have determined the percentage of heat from solar radiation actually delivered to a room with various types of outdoor and indoor shading. The data in Table 7 are taken from these tests. Table 7. Solar Radiation Transmitted Through Shaded Windows TTPB 07 Appuktbnancb Finish Facing '. Sun Canvas awning:------------------------------- ------------ :-........... -- --- Plain Canvas awning.---------------------------------------- ....-........... Aluminum Inside shade, fully drawn..--^---- -----------------------'.....------------- Aluminum Inside shade, one-half drawn_--.1:--- ------------------------ ---------- Buff Inside Venetian blind, fully covering window, slats at 45 deg.----- Aluminum Outside Venetian blind, fully covering window, slats at 45 deg-- Aluminum Pkb Cent. Deuvxhbb to Rook 28 22 45 68 58 22 `Heat Absorbing Glass Windows, by W. W. Shaver (A.S.H.V.E. Transactions, Vol. 41, 1935, p. 287). 7A S.H.V E. Research Report No. 974--Radiation of Energy Through Glass, by J. E. Blackshaw and F. C. Houghten (A.S.H.V.E. Transactions. Vol. 40,1934. p. 93). A.S.H.V.E. Research Report No. 975 --Studies of Solar Radiation Through Bare and Shaded Windows, by K. C. Houghten, Carl Gutberlet, and J. L. Blackshaw (A.S.H.V.E. Transactions, Vol. 40. 1934. p. 101). A.S.H.V.E. Research Report No. 1180--Heat Gain Through Western Windows With and Without Shading, by F. C. Houghten and David Shore (A.S.H.V.E. Transactions, Vol. 47, 1941, p. 251). . Loc. Cit. Note 7.