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' ( <br /> I � � <br /> � <br /> F R A N K L I N ��:,�o�rtit, ���n� �;��5���-�3;�� <br /> ���.e zoa F,�Y�z�s�?-���z <br /> ENGINEERING r ����n�. ;�,�, ���:��, -�����=,�,,<,��:^��m <br /> Pa1ECrTNICAL CORSULT I^IG <br /> U-value Calculation �or "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 0.2916 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 /> 1 otal UA 4.980 Total UA 4.050 <br /> Average U-value= U;,= UA/A U.= 0.053 Average U-value = Ua= UA/A U.= 0.043 <br /> R-19 batts R-25 batts <br /> R-30 Batts R-38 Batts <br /> U-value Area UA U-value Area UA <br /> Vent Gap 1.13 02916 0.330 Vent Gap 1.13 02916 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 = U,= UA/A U.= 0.029 <br /> R-30 batts R-38 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 inZ/144 in2 - 0.2916 ttZ <br /> Vent Ga Area =0.2916 ft2 U•value of Vent Ga = 1.13 <br /> Light Fixtures Insulation <br /> Assume: Area of insulation <br /> 112 watts/fixture z = area of Light Fixtures-area of Vent Gap <br /> z = 93.3 f[ <br /> 1.2 watls✓fi Area ot insulation = 93.3 - 0.2916 <br /> 1 L( ht FiMure er 93.3 ft2 Insulation Area_93.0084 tt <br /> \ <br /> � �I (,�`v <br /> ` r) <br />