Document oeM4Rz035QQVRX2p1Eqo3g8Mo

150 CHAPTER 11 1960 Guide Table 1.... Infiltration Through Wads* Exprotsod fa obk foot par (tquare food (bear) Tfpo of Woff Wind Vofodty, A4Sot pot Hoar 5 10 !5 20 25 30 Brick Wall* 8H in. Plain Plastered* Plain 13 in. Plastered* Plastered*1 2 4 8 12 19 23 0.02 0.04 0.07 0.11 0.16 0.24 1 4 7 12 16 21 0.01 3.01 0.03 0.04 0.07 0.10 0.03 0.10 0.21 0.36 0.53 0.72 Frame Wall, lath and plas- 0.03 0.07 0.13 0.18 0.23 0.26 ter* * CmVwMd of pawn brick ud lima mortor--pooo. * Two coot* prepared gypanm plaster on brick. 0 Fsnisi, litb, tad (ws coat* ptnand (ppnua pi--t-- on brick. * W1 caaotraetloa: bnti --or coder Mnftm nfralhinr. build up* paper, wood taih, tsd three coot* gypsum plaster. office building, with imperfect sealing of plaster at the base boards of the rooms. With perfect seating the range is from 0.5 to 2.7 percent; or a practically negligible quantity, which indicates the importance of good workmanship for proper sealing at the baseboard. It will be noted from Table I that the infiltration through properly plastered walls be neglected. The value of building paper, when applied between sheathing and shingles, is indicated by curve 3D-7D, Fig. 1, which represents the effect on outside construction only, without lath and plaster. The effectiveness of plaster prop erly applied is no justification for the use of low grade building paper, or of the poor construction of the wall con taining it. Not Only is it difficult to Secure and maintain the full effectiveness of the plaster, but also it is highly de sirable to have two points of high resistance to air flow with an air space between them. The infiltration indicated in Fig. 1 is that determined in the laboratory, and should be multiplied by the factor 0.80 to give proper working values. Window and Door Leakage There are two methods of .estimating air leakage through window and door cracks, namely, (1) the crack method, and (2) the air change method. The crack method is generally regarded as being more accurate than the air change method, provided the variables, such as crack width nH clearance, can be properly evaluated. Crack Method The crack method is based on known air leakage factors for various types of windows, and widths of crack and clearance. The wind velocity and length of crack are My* considered when the crack method is employed. The amount of infiltration for various types of windows is given in Table 2* The fit of double-hung wood windows is determined by crack and clearance. Crack thickness is equivalent to onehalf tiie difference between the inside window frame dimen sion and the outside sash width. The difference between the width of the window frame guide and the h t.hifkngg? is considered as the clearance. The length of the perimeter opening or crack for a double-bung window is equal to three times the width, plus two times the height, or in other words, rt is the outer sash perimeter length, plus the meeting rail length. All of the window crack in any given room is not necessarily used in estimating the infiltration beat loss by the crack method. The length of crack to be selected in any given case depends on the number of exposed rides, as explained in Chapter 12. Values of leakage shown in Table 2 for the average double-hung wood window were determined by using, on nine windows tested in the laboratory, the average measured crack and clearance of a large number of windows found in a field survey. In addition, the table gives figures for a poorly fitted window. All of the figures for double-hung wood windows are for the unlocked condition. Just how a window is closed, or fits when it is closed, has considerable influence on the leakage. The leakage will be high if the sash are short, if the meeting rail members are warped, or if the frame and sash are not fitted squarely to each other. It is possible to have a window with approximately the average crack and clearance that will have a leakage at least double that of the figures shown. Values for the aver age double-hung wood window in Table 2 are considered to be easily obtainable figures, provided the workmanship on the window is good. Should it be known that the windows under consideration are poorly fitted, the larger leakage values should be used. Locking a window generally decreases its leakage, but in some cases may push the mating rail members apart and increase the leakage. On windows with large clearances, locking will usually reduce the leakage. Wood casement windows may be assumed to have the same unit leakage as for the average double-hung wood window when property fitted. Locking, a normal operation in the closing of this type of window, maintains the crack at a low value. For a metal pivoted sash, the length of crack is the total perimeter of the movable or ventilating sections. Frame leakage on steel windows may be neglected when they are properly grouted with cement mortar into brick work or concrete. When they are not properly the Km*** feet of sash section in contact with steel work at mullions should be figured at 25 percent of the values given in Table 2 for industrial pivoted windows. When storm sash are applied to well fitted windows, some Types of Shingle Construction Infiltration and Ventilation 151 Typ* of Window Toble 2 .... Infiltration Through Windows Expressed in cubic feet pec foot of crock pot hoar* Wind Velocity, Mites pot How 5 10 15 20 25 30 Around frame in masonry wall--not calked*........................ 3 8 14 20 27 35 Around frame in masonry wall--calked*................................ 1 2 3 4 5 6 Around frame in wood frame construction*.......................... 2 6 11 17 23 30 Total for average window, uon-weatherstripped, Ha-in- Double-Hung Wood Sash crack and clearance.* Includes wood frame leak- Windows (Unlocked) age"............................................................................................. Ditto, weatberstrippedd................................. .......................... 7 4 21 13 39 59 80 104 24 36 49 63 Total for poorly fitted window, non-weatheratripped, Ha- in. crack and Ha*"t- clearance.* Includes wood frame leakage-...................................................................................... 27 69 111 154 199 249 Ditto, weatherstripped-............................................................. 6 19 34 51 71 92 Double-Hung Metal Windows* Non-weatherstripped, locked................................................... Non-weatberstripped, unlocked............................................... Weatheretripped, unlocked........................................................ 20 20 6 45 47 19 70 96 125 154 74 104 137 170 32 46 60 76 Rolled Section Steel Sash Windows* Industrial pivoted, Ha'in. crack*................................... ........ Architectural projected, Ha*in. crack*................................... Architectural projected, K-in. crack*.................................. Residential casement, H-in. crack1....................................... Residential casement, Ha-in. crack*....................................... Heavy casement section, projected, Ho-io. crack'.............. Heavy casement section, projected, Hs-in- crack1.............. 52 15 20 6 14 3 8 108 36 52 18 32 10 24 176 244 304 372 62 86 112 139 88 116 152 182 33 47 60 74 52 76 LOO 125 18 26 36 48 38 54 72 .92 Hollow Metal, Vertically Pivoted Window1......................................................................... 30 88 145 186 221 242 * Tte values pita in table, with the exception d time for doabto-buB and hollo* nebl window* are S percent las than test values to allow tor baildui op l pressure in rooms, and are based on test data, reported la the papers listed m chapter footsMsa- * Tbs values liven lar tramsleakage are per loot of sash perimeter, as determined brdnbls-bani wood windows. 8oa*eof the fiaae leakage in mamxur one- inales in tbs brick wall itself, and "* be prevented by calkins, roc tba additions! reason that calkins is not done perfectly and deteriorates with tune, it a con sidered odvnbfe to chores the masonry frame leakage values for calked fraines as the average determined by tbs calked and oco-calked tests. * The fit of tbs average double-bun* wood window was s Ms-in. crack and He-in. clearance by measurements on approximately SOD windows under beating season renditions. * Tbs values siren am tbs totals for tbe window opening per foot of sash perimeter, and inelnde frame Icakacs end so-called risrtptrm faofeas*. The frame Irekogo values included are for wood frame eonsWustaon, but apply os well to masonry uoustiaction stsnmins a 50 qurottif efficiency cs frame calkins. * A fos-in. crack and clearance represent s poorly fitted window, much poorer than average. 1 Windows tested ia ptoee in building, so that no reduction from test volure is ueutiisry, as mentioned in footnote a. s ladtstrisl pivoted window pianJiy used in indmtrisl buildings. Ventilotcre b--*--*ny pivoted at center or slightly shore, lower tmrt swinging out. * Architecturally projected made af same sections as industrial pivoted, except that outside framing member is heavier, and it has refinements in weathering and hardware. Used in wwi.wMMunMt^ Kmidiwpi meh as selmoia. Ventilators swing in or put and are balsnrvd oc side arms. Ms-in- trees s obtainable in too best preo- tice of manufacture and installation. M*-m. aack considered to represent avenge practice. * Of some /4y*c,> and section shapes as so-ealled kaosy lection coseaeai, bat of lighter weight. Ms-in. crack is obtainable in tbs best pnriice rf manufacture and in stallation, Ms-ia. crack considered to mptrstnt avenge practice. i Made of heavy sections. Ventilator* string in or out and stay set at any degree of opening. Ms-in. creek is obtainable in tbe best practice of manufacture aod in stallation, Ms-tn- creek contkfoiod to rtpetrent avenge practice. Known os Intermediate Windows by steel window manufacturers. k With rmonshlr care in I--at contacts where windows are attached to steel framework sad at nralltoBa, a negligible. With M-in. aack, repre- apoar t--tetiat*i Icabgo at eantactwiut steel framework is about one third, and at mullions, about rasshtb of that given for industrial pivoted windows at B. reduction in infiltration is secured; the application of the sash provides an air space which reduces the heat trans mission and helps prevent the frosting of the windows* By applying storm sash to poorly fitted windows, a reduction in leakage of 50 percent may be obtained, the effect, so far as air leakage is concerned, being roughly equivalent to that obtained by the installation of weatherstrips. Door Leakage Doors vary greatly in fit because of their large size and tendency to warp. For a well fitted door, the leakage values for a poorly fitted double-hung wood window may be used. If poorly fitted, twice this figure should be used. If weatherstripped, the values may be reduced one-half. A single door that is frequently opened, , as might be the case in a store, should have a value applied three times that for a well fitted door. This extra allowance is for opening and closing losses, and is kept from being greater by tbe fact that doors are not used as much in the coldest and windiest weather. The infiltration rate through swinging and revolving doors is generally a matter of judgment by the engineer making x-' cooling load determinations. In the absence of adequate re search data, the values given in Table 3 may be used to represent current engineering practice. Some tests of infiltra tion through swinging and revolving doors have been re ported-* The data in Table 3 are indicative of what might be expected in this connection, but it should be noted that Table 3 is based on a no-wind condition, and therefore is not directly applicable to heating design. A wide range of infiltration rates would be expected for swinging doors because of variations in the indoor-outdoor pressure difference caused by wind, temperature differences, and the degree to which a heating or an air-conditioning