EnergyPlus does not calculate return on investment but does provide a lot of features related to economics that you can use in calculating return on investment. The first costs can for a building can be computed using the ComponentCost:* objects, monthly utility bills can be computed using the UtilityCost:* objects and to compute the present value of investments including utility costs, the LifeCycleCost:* objects can be used. These are all described in the document for Economics.