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Iw <br />FRANKLIN <br />ENGINEERING <br />ME -' HANICA I. CON5lAT ING <br />625 Fourth Avenue <br />5uite 202 <br />Kirklard WA 96033 <br />PH 425 827.3324 <br />FAX 425 827-6252 <br />hvaUmfrankI neng.com <br />U-value Calculation for "Vented" T-bar Ceiling with Light Fixtures <br />R-19 Batts <br />U-value Area I UA <br />Vent Gap 1.131 0.29161 0.330 <br />Insulation R-19 0.051 93.00841 4.650 <br />Total UA 4.980 <br />Average U-value = U, = UA/A F7 U, _ "' 0.053 <br />'''R-19 betts'- <br />R-30 Batts <br />U-value Area UA <br />Vent Gap 1 1.131 0.29161 0.330 <br />Insulation R-30 0.0341 93.00841 3.162 <br />Total UA 3.492 <br />Average U-value = U, - UA/A r .4 ^U; - ,Y , 0.037 <br />'R•30 baits ..: <br />Gap <br />U-value = U. - UA/A U. = 0.043 <br />R-38 Batts <br />U-value Area UA <br />Vent Gap 1.131 0.2916 0.330 <br />Insulation R-38 0.0261 93.0084 2.418 <br />Total UA 2.748 <br />Average U-value - U. - UA/A <br />R38 baits <br />Background Calculations <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 inz/144 in - 0.2916 it' <br />Vent Gap Area = 0.291611' <br />Assume: <br />112 watts/fixture= 93.3 its <br />1.2 walts/fI <br />1 LI ht Fixture per 93.3 ft <br />U-value of Vent Ga = 1.13 <br />Area of insulation <br />- area of Light Fixtures - area of Vent Gap <br />Area of insulation - 93.3 - 0.2916 <br />Insulation Area = 97084 ft <br />7/1 <br />