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s � <br />r- <br />FRANKLIN <br />ENGINEERING <br />PH 425 P27-3324 <br />FAX 425 E•27-6252 <br />hia,Ofiark i,en© rn <br />U-value Calculation for "Vented" T-bar Ceiling with Light Fixtures <br />Gap <br />U-value = U, = U/VA I U. = 0.053 <br />R-19 batty_ J <br />R-30 <br />Vent Gap <br />Insulation <br />U-value = U, = UA/A <br />lal UA 3 492 <br />U. = 0.037 <br />R-30 belts <br />R-25 Batts <br />U-value <br />I Area UA <br />Vent Gap <br />1 1.131 <br />0.2916 0.330 <br />Insulation R-251 <br />0.041 <br />93.0084 3.720 <br />Total UA 4.050 <br />Average U-value - <br />U, - UA/A <br />U. = 0.043 <br />R-25 batty <br />R-38 Batts <br />Gap <br />U-value = U, = !JA A I U. = 0.029 <br />R-38_betts <br />Vent Gap <br />Size: 7/8" Wdo by 48" long U-value of vent gap: <br />Area - 7/8 x 48 - 42In2 Assume R-0.88, 1/R=U=1.13 <br />42 in2/144 inx - 0.2916112 <br />Vent Gap Area = 0.2916 ft2 U-value of Vent Gap = 1.13 <br />!s <br />Assume: <br />112 wal_ atIS/fa = 93.3 it2 <br />1.2 watls/11 <br />1 Light Fixture per 93.3 771 <br />n <br />Area of insulation <br />= area of Ught Fixtures - area of Vent Gap <br />Area of Insulation - 93.3 - 0.2916 <br />Insu4dlon Area = 93.0084 ft <br />0/9 <br />