Document ppBw2rKMMJ3krM7qzg7k8xZpd

American Society, of Heating and Ventilating Engineers Guide, Heat Loss B.t,u. 8a. Ft. per Hour Radiation 0-70*F. T a b l e 18. n f il t r a t io n through R o lle d Sec tio n St e e l W indow sI Per Foot o f Crack of Ventilating Sash IL sh eg Ij IP !s Heat Loss B,t.u. per Hour o-ro^F. iO'0-<>eMO'0ri>p .*o S2 22 2i jI O' *t--o* CoM COM' r0*50u-"05 1 ' *SZt-co fj * aCO 5> Leakage Cu. Ft. per Hour SmSSSS II oo^oo^egso B eg 5 o6j O a ..s cm ro vo oo <g . CS'OcCmOv-tdolOo CpONm| r,pTCoOiol (iNo<o5 ' 'SM N0*C-*'fN* yO|yM)'f0. s. . , o*. 'OO'M'O ' "J * eQuuMOsACG9 *1 O^f'OCMiOp*lbs'OOc0q0 Leakage Cu. Ft. per Hour sS jfgB ||j Leakage Cu. Ft. per Hour. Heat Loss B.t.u. per Hour 0-70*F. 0.34 0.71 1.16 1.60. 2.00 2.44 fO^OONOOt-. ** ^ CO 00 co erf CM f<On CN *0 \o 0.27 0.57 0.93 1.28 1.60 1.95 '-'Mr*.rr>'O-Qh oiH 0 0 0 0*0-^ O'Oh'OhM CM CM lCOM 0000 ---*h CM CO0M0 "SS-3H St ." S3 -*Ss1coJ24 o S'- n 5 si II* J-lfo ,ris. > esi t c*j v Soi a 3 si 3v i3 Leakage Cu.Ft: per Hour jfigi CM C*} c*} "'SISSJOS? 1 ")ooo ~< CM CM CO if CM CN C*} =J o tl a PART I Values actually deter* mined by Laboratory 1 tests. PART II Valuesfor practical use; test values reduced 20 per cent to allow for building up of pressurein room, etc. ii-!si&S . s> 54 Chapter I--Heat Losses from Buildings Table 19. Infiltration through a Hollow Metal Vertically Pivoted Steel 1' , Window, Installed in a Building. Wind Velocitt Miles per Hour 5 10 15 20 25 30 Leakage Cu. Pr. per Hour Per Foot op Crack 29.5 88.5 144.5 186.0 221.5 242.0 Heat Loss B.t.u. pee Hour 0-70 Dbg. Fahs. 37 112 182 234 279 305 Squabs Foot Radiation 0.15 0.47 0.76 0.98 1.16 1.27 containing the same values reduced by 20 per cent in accordance with the suggestion of the authors. According to the authors of the papers: "The values given in the tables are from the tests as made and are probably somewhat higher than those actually found in practice. They represent the leakage when the pressure drop through the window is a certain value which represents a definite wind velocity at right angles to the window. If the wind strikes the window at an oblique angle the component of the velocity at right angles to the window must be considered. Pressure difference between the outside and the inside surfaces of the window for an actual wind will be slightly less for a given velocity because of a building up of pressure within the room before the air leaks out the opposite side of the building. Attention is called to the fact that air leaks in on the windward side of the building and out on the leeward side and, since wind will blow from various directions at different times, heating for any room having only one exposure must be based on. the maximum loss. The heating plant, however, need not be figured on the sum of all maximum leakages, but in general only half of the total. However, the table gives accurate comparative figures which are probably not much too high for actual practice. In order to apply these values, a further study of the overall results as found in practice should be made, and the figures modified, if necessary, to fit practical conditions." In their discussion of results on tests of double-hung wood sash windows as presented in the Transactions, A. S. H. & V. E., Vol. 30, 1924, p. 313, the authors state: "The principal facts brought out in the first report were that increasing the crack around the perimeter of a plain sash did not materially increase the leakage, and that weatherstripped sash, while permitting much less leakage, showed a small increase in leakage with increase in crack. These facts were established by making several hundred tests. The present report deals with the effect of increasing the width of the stile, that is, increasing the clearance. " Fig. 5 illustrates what is meant by crack and clearance. The crack around the sash perimeter is equal to one half the difference between the width of the frame and the width of the sash, that is, the crack is the same on each side of the sash. The clearance is the difference between the width of the stile and the thickness of the sash. These terms are chosen arbi trarily to distinguish the two principal air passages which are found in double-hung windows. 55