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• �* � <br /> U-vaba�: Calculation for "Vented'" T-bar Ceiling with Light Fixtures <br /> Franklin Engineering <br /> February.�.5;-2082 <br /> Y/eM Gap � <br /> Size: 7/8"wide by 48"long U-value oi vent gap: <br /> Area=7/8 x 48=42 In=/144 inZ=0.2918 fl� Assume R�.EfB, t/R=U=1.13 <br /> Vant 6ap Ar�a�0.2918 �valua of Vant Oap�'1.13 <br /> LIgM Fbctures <br /> Assume: <br /> --�I-12 warislfixlure =93.3 fl� <br /> 1.z wan <br /> 1 LI&nt F�zturo per 93.3 <br /> lireulatlon � <br /> Area of insulation=area of Light Fixlures-area of Vent Gap <br /> ----�� Area of fnsuloliori=93.3-0.2916 <br /> Insulatlon Area!93.0034�� <br /> Averape U-valua oi Celling wlth R-79 W�tt InaulaUon Average U-value of Celling wlth R:b beC Insulatlon <br /> U-value Area UA U-value Area UA <br /> Vent G�., 1.13 02918 0.:330 Ven'� Gap 1.13 @.29�8 0.330 <br /> Insulation(R-19) 0.05 93.0084 4.850 Ins.. �tion(R-2b) 0.04 93.0084 3J20 <br /> ---- Tota:UA 4.980 Tc'. :llA 4.050 <br /> !'�verage U-value=U,=UA/A Average U-vatue=U,=UrVA <br /> R-19 bat4 � �W25�� <br /> Avenpe U-valuaof Celling wlth R-30 batt Inauiallon Aver�ge U-value ot Jeiiinp wlLh R-38 bat2lnsida�lon <br /> U•value Area UA U-ve;ue Nea UA� <br /> Vent Gap 1.13 0.2918 0.330 Vent Gap 1.t3 0:2918 Q33U <br /> Insula!ion(R30) 0.034 93.0084 3.16� Insulation R-38 0.028 93.008i 2.41II <br /> raai ua 3.492 Tm!al Uh �2�74? <br /> Average U-value=U.= UA/A Average U-v21u6=U,=UA/A <br /> C U,� 0.037 U,� 0.888 <br /> R30 batts R3N batb <br /> C% <br />