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� i i <br /> I — � <br /> — <br /> � � � � K � � � �25 Focrsh Aver.u^ PH 425 027-332� <br /> ENGIIMEERING =�'Le 2°2 FP„���F���_���2 <br /> Y rF.lanc '!/A 9°�CiJJ ^vacC��ra�kli�eraCcm <br /> P�1kG—AtJICAL GOP,S�L71�G <br /> U-value Calculation for "Vented" T-bar Ceiling with Light Fixtures <br /> R-19 Batts R-25 Batts <br /> U•value Area UA U-value Area UA <br /> Vent Gap 1.13 02916 0.330 Vent Gap 1.13 0.2916 0.330 <br /> Insulation R-19 0.05 93.0084 4.650 Insulation R-25 0.04 93.0084 3.720 <br /> Total UA 4.980 Total UA 4.050 <br /> Average U-value = U,= UA/A U,= 0.053 Average U-value = L',= UA/A U,= 0.043 <br /> R-19 batts R-25 batts <br /> R-30 Batts A-38 Batts <br /> U-value Area UA U-value Area UA <br /> Vent Gap 1.13 0.2916 0.330 Vent Gap 1.13 0.2916 0.330 <br /> Insulation R-30 0.034 93.0084 3.162 Insulation R-38 0.026 93.0084 2.418 <br /> Total UA 3.492 Total UA 2.748 <br /> Average U-value = U� = UA/A U,= 0.037 Average U-value = Ua= UA/A U,= 0.029 <br /> R-30 batts R�8 batts <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 inZ Assume R=0.88, 1/R=U=1.13 <br /> 42 in2/144 in2 = 0.2916 ftz <br /> Vent Ga Area = 0.2916 ftx U-value of Vent Ga = 1.13 <br /> Light Fixtures Insulation <br /> Assume: Area of insulation <br /> 112 watts/fixture Z = area o( Light Fixtures-area ot Vent Gap <br /> 1.2 watls�itZ - 93.3 ft Area of insulation = 93.3- 0.2916 <br /> 1 Light Fixture per 93.3 tt Insulation Area =93.0084 ft <br /> '�� =j,: <br /> ��- <br />