I have created a model builder to calculate the centroid of a polygon and then export it to a point feature class. The output coordinates is set to IRENET95_Irish_Transverse_Mercator. I would like to calculate the Lat and Long values for the point feature class in decimal degrees. Does anyone know how to calculate this using Model builder. I know it can be done in desktop by using the Calculate Geometry tool and change the units to Decimal Degrees. Any help would be appreciated.

You may need to apply a datum transformation, depending on whether or not you want the lat/lon values based on the datum of your current projection (i.e. GCS_IRENET95). The datum transformation can be supplied as one of the parameters to the Project tool, if required.

For example, an appropriate transformation to convert to WGS84 lat/lon would be IRENET95_To_WGS_1984_1 (wkid = 1678)