|  1 |    initial version    |  
You can replace the  CoolingTower:TwoSpeed object for a DistricCooling object. Set your Sizing:Parameters Cooling Sizing Factor to 1.15. Run the simulation and search for the autosized value of the "DistrictCooling' and then replace the object with your CoolingTower and set the nominal capacity to be the same as the DistrictCooling. 
You will need to calculate the Free convection capacity as detailed here.
    |  2 |    No.2 Revision    |  
You can replace the  If you want to autosize a cooling tower, choose your tower CoolingTower:TwoSpeedPerformance Input Methodobject for a to be DistricCoolingUFactorTimesAreaAndDesignWaterFlowRateobject. Set it can be auto-sized if you leave the default values. 
As for the oversizing factor required by code, change your Sizing:Parameters Cooling Sizing Factor to 1.15. Run the simulation and search for the autosized value of the "DistrictCooling' and then replace the object with your 1.15.CoolingTower and set the nominal capacity to be the same as the DistrictCooling. 
You will need to calculate the Free convection capacity as detailed here.