Document dY1MnERmjnGm3YxZXDxGO9gRq

American Society of Heating and Ventilating Engineers Guide, 1936 The amount of infiltration that may be expected through simple walls used in farm and other shelter buildings, is shown in Fig. 2. The infil tration indicated in Figs. 1 and 2 is that determined in the laboratory and should be multiplied by the factor 0.80 to give proper working values. WINDOW LEAKAGE 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 as illustrated in Fig. 3. The length of the perimeter opening or crack for a double-hung window is equal to three times the width plus two times the height, or in other words, it is the outer sash perimeter length plus the meeting rail length. Values of leakage shown in Table 2 for the average double-hung wood window were determined by setting the average measured crack and clearance found in a field survey of a large number of windows on nine windows tested in the laboratory. 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 doublehung wood window in Table 2 are considered to be easily obtainable figures provided the workmanship oh 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. Locking, 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 per cent of the values for industrial pivoted windows as given in Table 2. Leakage values for storm sash are given in Figs. 4 and 5. When storm sash are applied to well fitted windows, very little reduction in infiltration is secured, but the application of the sash does give an air space which reduces the heat transmission and helps prevent the frosting of the windows. When storm sash are applied to poorly fitted windows, a. reduction in leakage of 50 per cent may be secured. 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 Chapter 6--Air Leakage Table 2. Infiltration Through Windows Expressed in Cubic Feet per Foot of Crock per Houm T *tt or Window PeifAPTtB Worn Velocity, Mn.es psa Houn 5 10 15 20 25 30 ---- ---------: A/ouod frame in masonry wall--not calked** 3.3 8.2 14.0 20.2 27.2 34.6 Around frame in masonry wall--oalkedb------ 0.5 1.5 Around frame in wood frame construction**-- 2.2 6.2 2.6 10.8 3.8 16.6 4.8 23.0 5.8 30.3 Double-Hung Total for average window, non-weather- Wood Sash stripped. 56-*n- crack and 56-in. clearance. 6.6 21.4 39.3 Includes wood frame leakage*----------------- - (Unlocked) Ditto, weatbcrstrippedd------------------------------- 4.3 15.5 23.6 59.3 35.5 80.0 103.7 48.6 63.4 TnfnI for noorlv fitted window, non-weather- strippea, 56-m. crack and 56-in. clearance. Includes wood frame leakage*------------------- Ditto, weatherstrippedd------- ----------------------- 26.9 69.0 110.5 5.9 18.9 34.1 153.9 51.4 199.2 70.5 249.4 91.5 Double-Hung Non-weatherstripped, locked-- ------- Non-weatherstripped, unlocked.. ,,. . Windows! Weatherstripped, unlocked--....................-- 20 20 6 OcL&ll Windows1* Industrial pivoteds. 56-in. crack---------------Architectural projected, 56*in* crack**------ -- Architectural projected, 56-in. crack**---------Residential casement, 56-in. crack* Residential casement, 56-in. crack* Heavy casement section, projected, 56-in. Heavy casement section, projected 56-in. cracki___ ------------------------------------------- 52 15 20 6 14 3 8 45 47 19 108 36 52 18 32 10 24 70 74 32 176 62 88 33 52 18 38 96 125 104 137 46 60 244 86 116 47 76 26 54 . 304 112 152 60 100 36 72 154 170 76 372 139 182 74 128 48 92 Hollow Metal, vertically pivoted window!. 30 88 145 186 221 242 The values given in this table are 20 per cent less than test values to allow for building up of pressure in rooms, and are based on test data reported in the papers listed at the end of this chapter. bTbe values given for frame leakage are per foot of sash perimeter as determined for double-hung wood windows. Some of the frame leakage in masonry walls originates in the brick wall itself and cannot be prevented by calking. For the additional reason that calking is not done perfectly and deteriorates with' time, it is considered advisable to choose the masonry frame leakage values for calked frames as the average determined.by the calked and not-calked tests. oThe fit of the average double-hung wood window was determined as J6-ln. crack and 56-in. clearance by measurements on approximately 600 windows under heating season conditions. *The values 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 wood frame construction but apply as well to masonry construction assuming a 60 per cent efficiency of frame calking. . A 56-in. crack and clearance represents a poorly fitted window, much poorer than average. Windows tested in place in building. (Industrial pivoted window generally used in industrial buildings. Ventilators horizontally pivoted at center or slightly above, lower part swinging out. ^Architectural projected made of same sections as industrial pivoted except that outside framing member is heavier, and refinements in weathering and hardware. Used in semi-monumental buildings such as schools. Ventilators swing in or out and are balanced on side arms. in- crack is obtainable in the best practice of manufacture and installation, 56 in. crack considered to represent average practice. *Of same design and section shapes as so-called heavy section casement but of lighter weight. 16 >n- crack is obtainable in the best practice of manufacture and installation, 56 in. crack considered to represent average practice. iMade of heavy sections. Ventilators swing in or out and stay set at any degree of opening. 56 in* crack is obtainable in the best practice of manufacture and installation,'56 in* crack considered to represent average practice. With reasonable care in installation, leakage at contacts where windows are attached to steel fraxne*nric and at mullions is negligible. With 56-in. crack, representing poor installation, leakage at contact with steel framework is about one-third, and at mullions about one-sixtb of that given for industrial pivoted windows in the table. 135