The second equation

The second equation determines G1 , the moisture content of the air at the air handler outlet.  G2 = .011, the moisture content of the 80F and 50% RH air in the space.  The moister content is
                          G1  =.011 – 8354/ (4840x2137) = .0102 lb/lb dry air
With this value, the point 1 shown in Figure 4 can be located on the psychrometric chart.  From .0102 on the moisture scale extend a horizontal line to intersect with a vertical line at 65F. This point 1 can also be located or checked using the sensible heat ratio given by Equation 10
                       SHR = 35274/ (35274+8354) = .81
From .81 on the SHR scale draw a line through point 2 and extend it to intersect the 65F line to again define point 1.  Extending the horizontal line from this point to the 100% relative humidity curve locates point 5 shown in Figures 3 and 4.  This gives the dew point temperature of 59F.  This is the required cooling coil temperature of the air conditioning unit.
Point 4 shown in Figures 3 and 4 is the condition of the air entering the cooling coil.  This point can be found from the following equation: