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F R A N K L, I N 625 Fourth Avc•xz PH 425 827-3324 <br />5wt- 202 FAX 425 827-6252 <br />ENGINEERING KrklanAWA 1.8J33 hvac@fraridinc-%corn <br />MECHANICAL CON5ULTING <br />U-value Calculation for "Vented" T-bar Ceiling with Light Fixtures <br />R-19 Batts <br />U-value Area UA <br />Vent Gap 1.131 0.29161 0.330 <br />Insulation (R-1911 0.051 93.00841 4.650 <br />Total UA 4. 880 <br />Average U-value = U, = UA/A U. = 0.053 <br />R-19 hafts <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 U. = 0.037 <br />R-30 batts <br />R-25 Batts <br />U-value I Area UA <br />Vent Gap 1 1.131 0.29,161 0.330 <br />Insulation R.25 0,041 93.00841 3.720 <br />Total UA 4.050 <br />Average U-valuo = U, = UA/A U■ = 0.043 <br />R-25 batts <br />R-38 Batts <br />U-value Area UA <br />Vent Gap 1.131 u.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 F 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 fl' <br />Vent Gap Area = 0,2916 ft U-value of Vent Ga = 1.13 <br />!s <br />Assume: <br />112 watts/fixture = 93.3 fl2 <br />1.2 watts/fl <br />1 Light Fixture per 93.3 ft <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 tt <br />i <br />r J �� <br />