Document 0w6yowKqd3xVGnemJaO7RER

HEATINC VENTILAT1NC AIR CONDITIONING GUIDE 1944 Table 2. Infiltration Through Windows Expressed in Cubic Feet per Foot of Crack per Hour* Tips op Window Remarks Wind Velocitt, Miles per Hour 5 10 15 20 25 30 Around frame in masonry wall--not ealkedb 3.3 8.2 14.0 20.2 27.2 34.6 Around frame in masonry wall--ealkedb___ 0.5 1.5 2.6 3.8 4.8 5.8' Around frame in wood frame conatraetionb__ 2.2 6.2 10.8 Double-Hung Wood Sash Total for average window, non-weatherstripped, ha-in. crack and fit-in. clearances Windows Includes wood frame lenka/rod 6.6 21.4 39.3 (Unlocked) Ditto. weatherstrinnedd 4.3 13.0 23.6 16.6 59.3 35.5 23.0 80.0 48.6 30.3 1037 63.4 Total for poorly fitted window, non-weather- stripped, hrin. crack and ffj-in. clearance,a Includes wood frame lenVnTed 26.9 69.0 110.5 153.9 199.2 249.4 Ditto, weatherstrimwdd Double-Hung Non-weatheratrinped, Inr.VpH Metal Non-weathenrtrinped, nnbyrimi Windows* WeatheratrippeH 5.9 18.9 34.1 51.4 70.5 91.5 20 45 70 96 125 154 20 47 74 104 137 170 6 19 32 46 60 76 Industrial pivoted. 14-in. cmr.ke 52 108 176 244 304 372 Rolled Architectural projected, J^-in. crackh_____ 15 36 62 86 112 139 Section Architectural projected, f-in. crackh_____ 20 52 88 116 152 182 Steel Residential casement. W,-5n erneVi 6 18 33 47 60 74 Sash Windows'1 Residential casement, eracki _ Heavy casement section, projected, 1^-in. cradrj ` Heavy casement section, projected 14 3 32 10 52 18 76 100 128 26 36 48 8 24 38 54 72 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 windows, 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 non-calked tests. cThe fit of the average double-hung wood window was determined as >-in. crack and f-ln. clearance by measurements on approximately 600 windows under heating season conditions. <*Tbe 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 leakagegralues included are for wood frame construction but apply as well to masonry construction assuming a 50 per cent efficiency of frame calking. A *-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. bArchitecturally projected made of same sections as industrial pivoted except that outside framing member . is heavier, and it has refinements in weathering and hardware. Used in semi-monumental buildings -such as schools. Ventilators swing in or out and are balanced on side arms. J^-in. crack is obtainable in the best practice of manufacture and installation, f-in. crack considered to represent average practice. Of same design and section shapes as so-called heavy section casement but of lighter weight. &-in. crack pisroabcttiacien.able in the best practice of manufacture and installation, &-in. crack considered to represent average iMade of heavy sections. Ventilators swing in or out and stay set at any degree of opening. &-in. crack aisveorbatgaeinparbalceticine. the best practice of manufacture and installation, J6*in. crack considered to represent kWith reasonable care in installation, leakage at contacts where windows are attached to steel frame work and at mullions is negligible. With %-in. crack, representing poor installation, leakage at contact wwfinthdoswteselihfrathmeewtaobrlek.is about one-third, and at mullions about one-sixth of that given for industrial pivoted 120 CHAPTER 5. AIR LEAKACE The amount of infiltration for various types of windows is given in Table 22. The fit of double-hung wood windows is determined by crack and clearance. Crack thickness is equivalent to one-half the difference between the inside window frame dimension and the outside sash width. The difference between the width of the window frame guide and the 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 width plus two times the height, or in other words, it is the outer sash perimeter length plus the meeting rail length. Not all the window crack in any given room is necessarily used in estimating the infiltration heat loss by the crack method. The length of crack to be selected in any given case depends on the number of exposed sides as explained in Chapter 6. Values of leakage shown in Table 2 for the average double-hung wood window were determined by setting the average measured crack and clearance of a large number of windows found in a field survey 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 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. 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 wwk 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. JA.S.H.V.E. Research Reports No. 686--Air Leakage, by F. C. Houghten and C. C. Schrader (A.S.H.V.E. Transactions, Vol. 30, 1924. p. 105). No. 704--Air Leakage Around Window Openings, by C. C. Schrader (A.S.H.V.E. Transactions, Vol. 30, 1924, p. 313). No. 803--Air Leakage on Metal Windows in a Modern Office Building, by F. C. Houghten and M. E. O'Connell (A.S.H.V.E. Transactions, Vol. 34, 1928, p. 321). No. 815--Air Leakage Through a Pivoted Metal Window, by F. C. Houghten and M. E. O'Connell (A.S.H.V.E. Transactions, Vol. 34, 1928, p. 519). No. 817--Effect of Frame Calking and Storm Sash on Infiltration Around and Through Windows, by W. M. Richtmann and C. Braatz (A.S.H.V.E. Transactions, Vol. 34, 1928, p. 547). No. 90$--Air Infiltration Through Double-Hung Wood Windows, by G. L. Larson. D. W. Nelson and R. W. Kubasta (A.S.H.V.E. Transactions, VoL 37, 1931, p. 571). The Weathertightness of Rolled Section Steel Windows, by J. E. Emswiler and W. C. Randall (A.S.H.V.E. Transactions, Vol. 34, 1928, p. 527). Pressure Differences Across Windows in Relation to Wind Velocity, by J. E. Emswiler and W. C. Randall (A.S.H.V.E. Transactions, Vol. 36, 1930, p. 83): Air Infiltration Through Steel Framed Windows, by D. O. Rusk, V. H. Cherry and L. Boelter (A.S.H.V.E. Transactions, Vol. 39,1933, p. 169). 121