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FRANKLIN <br />ENGINEERING <br />M[CI IANICAL CON5ULTING <br />625 Fourth Avenue <br />5uwte 202 <br />Kirkland WA 98033 <br />Pli 425 827.3324 <br />FAX 425 827-6252 <br />hvac0(rank rcno.com <br />U-value Calculation for "Vented" T-bar Ceiling with Light Fixtures <br />R-19 Batts <br />U-value 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-valuo = U, = UA/A U, = 0.053 <br />R-19 betty <br />R-30 Batts <br />U-valuo I Area UA <br />Vent Gap 1.131 0.29161i0.330 <br />Insulation R-30 0.034 93-00841 3.162 <br />Total UA 3.492 <br />Average U-value = U, = UA/A Ug a 0.037 <br />R-30 batte <br />Calculations <br />R-25 Batts <br />U-value Area UA <br />Vent Gap 1.131 0.29161 0.330 <br />Insulation R-25 0.041 93.0084 3.720 <br />Total UA 4.055 <br />Average U-value = % = UA/A U. a 0.043 <br />R-25 batts <br />Vent Gap 1.13 0.2916 30 0.3 <br />Insulation R-38 0.026 95 .00841 2.418 <br />Total UA 2.748 <br />Average U-value = U, = UA/A U, a 0.029 <br />F148 bons <br />vent use <br />Size: 7/8" wide by 48" long U-valuo of vent gap: <br />Area = 7/8 x 48 = 42 in Assume R=0.88, 1/R=U=1.13 <br />42 In2/144 in = 0.2916 fl2 <br />Vent GagArea : 0.2916 tt' U-value of Vent Cie = 1.13 <br />Light Fixtures Insulation <br />Assume: Area of insulation <br />112 watts/fixlure Y = area of Light Fixtures - area of Von[ Gap <br />1.2 watis/112 = 93.31t Area of insulation = 93.3 - 0.2916 <br />1 Light Fixlure per 93.3 ft Insulation Area = 93,0084 ft <br />N// <br />