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I <br />FRANKLI_N <br />ENGINEERING <br />MECHANICAL CON5Ul TING <br />625 Fourth Avenu; <br />5wtc 202 <br />Kirkland WA 93033 <br />PH 425 82'-3324 <br />FAX 425 L327 -6252 <br />hvac 6 f ran.l ire rg.c om <br />U-value CalCulation for "Vented" T-bar Ceiling with Light Fixtures <br />R-19 Batts <br />U-value W4.650 <br />A <br />Vent Gap 1.13 0.330 <br />Insulation R-19 0.05 9 <br />Total UA 4.980 <br />Average U-value - U, = UA/A U. = 0.053 <br />R-19 bads <br />R-30 Batts <br />U-value <br />Arca <br />UA <br />Vent Gap 1.13 <br />0.2916 <br />0.330 <br />Insulation (R-30)l 0.0341 <br />q3.00841 <br />3.162 <br />Total UA <br />3.492 <br />Average U-value = U. = UAIA <br />U, = <br />0.037 <br />R•3G baits <br />Batts <br />Gap <br />Average U-vah re = U, = UA/A U, = 0.043 <br />R-25 baits <br />R-38 Batts <br />U-value <br />Area UA <br />Vent Gap 1 1,131 <br />0.2916 0 330 <br />nsulation (R-38( 0,0261 <br />93 0084 2.418 <br />Tota UA 2-748 <br />Average U-value = U;, = UA'A <br />U. = 0.029 <br />R-38 balls i <br />Backgrour d Calculations <br />Vent Gap <br />Size: 7/8" wide by 48" long U-value of vent gap: <br />Area a 718 x 48 - 42In2 Assume R.0.88, 1/R-U-1.13 <br />42 in2/144 in' - 0.2916 ft2 <br />Vent Gap Area = 0.2916 it` U-value of Vent Gap = 1.13 <br />Assume: <br />112 wars hxtu= . 93.3 ftZ <br />1.2 watts/ft <br />1 Light Fixture per 93.3 ft <br />il <br />Area of insulation <br />= area of Ught Fixtures - area of Vent Gap <br />Area of insulation = 93.3.0.2916 <br />Insulation Area = 93.0084 fe <br />