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F R A N K L I N 625 Fourth Avenue PH 425 81. 7-9324 <br />5wte 202W FAX 8276252 <br />ENGINEERING <br />Kirkland WA 98033 hvatru)frararticlineng.com <br />MECHANICAL CONSULTING <br />U-value Calculation for "Vented" T-bar Ceiling with Light Fixtures <br />R-19 Batts <br />U-value I Area UA <br />Vent Gap 1 1.131 0.29161 0,330 <br />Insulation R-191 0.051 93.00841 4.650 <br />Total UA 4.980 <br />Average U-value - U, - UA/A U. = 0.053 <br />R-19 batts <br />7 Batts <br />Gap <br />Average U-value - U. - UA/A I U. = 0.037 <br />R-30 bets <br />R-25 Batts <br />U-value <br />Area UA <br />Vent Gap <br />1.13 <br />0.2916 0.330 <br />Insulation R-25 <br />0.041 <br />93 0084 3.720 <br />lotal UA 4.050 <br />Average U•value - <br />U, - UA/A <br />R-25 belts <br />R-38 Be <br />Vent Gap <br />Insulation <br />U-value = U, = UA/A I U. = 0.029 <br />R-38 batts <br />Vent Gap <br />Size: 7/8" wide by 48" long U-value of vent gap: <br />Area - 7/8 x 48 -42 In' Assume R=0.88, 1/R=U=1.13 <br />42 in'/144 in' - 0.2916 It' <br />Vent Gap Area = 0.2916 ft U-value of Vent Gap = 1.113 <br />xtures <br />Assume: <br />112 2 watfs xt_u� <br />1.2 wattylt <br />1 Light Fixture per 93.3 It <br />n <br />Area of insulation <br />area of Light Fixtures - area of Vent Gap <br />Area of insulation - 93.3 - 0.2916 <br />Insulation Area = 93.0084 ft <br />