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F R A N K L I N 625 Fourth Avenue PH 425 527-3324 <br />ENGINEERING 5wtc 202 FAX fra B271i252 <br />Kirklard WA 98033 hvat�l+franY,hncngtom <br />MECHANICAL CAN5ULTING <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 1.13 0.2916 0.330 <br />Insulation R-19 0.051 93.0084 4.650 <br />Total UA 4.980 <br />Average U-value = U. = UAIA FU, = 0.053 <br />R-19 batts <br />1 Batts <br />U-value <br />Gap 1.13 <br />ition (R-3011 0.034 <br />Average U-value = U, = UA/A I U. = 0.037 <br />R-30 batts <br />nd Calculations <br />R-25 Batts <br />U-valu <br />vent Gap <br />1 <br />Insulation (R•25)C <br />Average U-value - <br />U. - UA/A <br />R-38 Batts <br />Vent Gap <br />0.29 <br />3.72( <br />U. = 0.043 <br />-25 balls <br />U-value - U, - UA/A U. = 0.029 <br />R-38 baits <br />Vent Gap <br />Size: 7/8" wide by 48" long U-value of vent gap: <br />Area. 7/8 x 48 = 42 inz Assume R-0.88, 1/R=U=1.13 <br />42 inz/144 in' = 0.2916 ftz <br />Vent Gap Area = 0.2916 ft U-value of Vent Ga = 1,13 <br />s <br />Assume: <br />112 watts/fixtu re = 93.3 fiz <br />1.2 wattyft <br />1 Light Fixture per 93.3 fl <br />Area of insulation <br />= area of Light Fixtures - area of Vent Gap <br />Area of insulation = 93.3 - 0.2916 <br />Insulation Area = 93.00811t` <br />s/� <br />