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242 CHAPTER 11 1957 Guide Table 2. Infiltration Through Windows Expressed in Cubic Feet per Foot of Crack per Hour* Tyfb of Window Wind Velocity, Miles pkb Hons 5 10 15 20 25 30 Double-Hung Wood Sash Windows (Un locked) Around frame in masonry wall--not calked**......... Around frame in masonry wall--calked. ........... Around frame in wood frame construction........... Total for average window, non-weather-etripped, Me-in. crack and 9i*-in clearance.0 Includes wood frame leakage*1 ............................................... Ditto, weatherstripped*-- ............................. ........ Total for poorly fitted window, non-weather- stripped, Ma-in. crack and Ma-in. clearance.* Includes wood frame leakage*................................ Ditto, weatheistripped*............................................... Non-weatherstripped, locked..................................... Non-weatherstripped, unlocked................................. Weatherstripped. unlocked......................................... Architectural projected. Mi-in. crack..................... Architectural projected, M4-in. crack..................... Residential casement. M-in. crack*......................... Heavy casement section, projected, Hi-in. crack? Heavy casement section, projected, Ha-in. crack* 3 1 2 7 4 27 6 20 6 52 15 20 6 14 3 8 8 14 20 27 35 2 3 4 56 6 11 17 23 30 21 39 59 80 104 13 24 36 49 63 69 19 111 34 ii 199 71 249 92 45 70 96 125 154 104 170 32 76 108 176 244 304 372 36 62 86 112 139 52 88 182 18 32 52 10 18 26 36 48 24 38 54 92 Hollow Metal, vertically pivoted window*...................................................... 30 88 145 186 221 242 The values given in this table, with the exception of those for double-hung and hollow metal window* are 20 percent lees than test values to allow for building up of pressure in rooms, and are based on test data, reported in the papers listed in chapter footnotes. h Tpho balnea given for frame leakage are per foot of sash perimeter, as determined for double-hung wood windows. Some of the frame leakage in masomy walls originates in the brick wall itself, and cannot be pre vented by calking. For the additional reason that calking is not done perfectly and deteriorates with fame, it is oonsidered advisable to choose the masonry frame leakage values for calked frames as the average deter mined by the calked and non-calked tests. The fit of the average double-hung wood window was determined as Ms-in. crack and M-in. clearance by measurements on approximately 000 windows under heating season conditions. d The valuee given are the totals for the window opening per foot of sash perimeter, and include frame leakage and so-called elsewhere leakage. The frame leakage values included are for woodframe construction, but apply as well to masonry construction assuming a 50 percent efficiency of frame calking. A *V-in. crack and clearance represent a poorly fitted window, much poorer than average. t Windows tested in place in building, so that no reduction from test values is necessary, as mentioned in footnote a. . Industrial pivoted window generally used in industrial buildings. Ventilators horizontally pivoted at center or slightly above, lower part swinging out. h Architecturally projected made of same sections as industrial pivoted, except that outside framing mem- her is heavier, and it has refinements in weathering and hardware. Used in semi-monumental buuaiw suoh as schools. Ventilators swing in or out and are balanced on side arms. Ha-in. crack isobtainablein beet practice of manufacture and installation, %-in. crack considered to represent average practice. 1 Of same d**ign and section shapes as so-called heavy tectum casement, but of lighterweight. Mv-in. crack is obtainable in the best practice of manufacture and installation. Ms-in. crack considered torepresentavew practice. .y J Made of heavy sections. Ventilators swing in or outund stay set at any degree of opening^Mi-m. isobtainable in the best practice of manufacture and installation. Ms-in. crack considered torepresentavera*" practice. Known as Intermediate Windows by steel window manufacturers. k With reasonable care in installation, leakage at contacts where windows are attached to steel work and at mullions, is negligible. With He-in..crack, representing poor installation, leakage at oonu^ with steel framework is about one third, and at mullions, about one-eixth of that given for industrial pi*0 windows in the table. 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 sbo clearance. Crack thickness is equivalent to one-half the difference be tween the inside window frame dimension and the outside sash wiattu The difference between the width of the window frame guide and tne sash thickness is considered as the clearance. The length of the perimeter opening or crack for a double-hung window is equal to three times the plus two times the height, or in other words, it is the outer sash perimeter length, plus the meeting rail length. All of the window crack in any ffveD *,- !? Infiltration and Ventilation 243 room is not necessarily used in estimating the infiltration heat loss by the crack method. The length of crack to be selected in any given case de pends on the number of exposed sides, 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 labora tory, 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 average 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 meeting 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 properly fitted. Lock ing, a normal operation in the closing of this type of window, maintains the crack at a low value. For 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 sealed, the linear 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 reduction in infiltration is secured; the application of the sash provides an air space which reduces the heat transmission and helps prevent the frosting of the win dows.* 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. w.ell fitted door, the leakage values for a poorly fitted double-hung window may be used. If poorly fitted, twice this figure should be used. If weatherstripped, the values may be reduced one-half. A single oor which is frequently opened, as might be the case in a store, should uuve a value applied which is three times that for a well fitted door. This evpt a~owance ^ for opening and closing losses, and is kept from being Blester by the fact that doors are not used as much in the coldest and windi est weather. if iuttement'The infiltration rate through swinging and revolving doors is generally a and ' by the engineer making cooling load determinations, u in the absence of adequate research data, the values given in Table 3 present current engineering practice. Some tests of infiltration through winging and revolving doors have been reported.4 The data in Table 3