The initial calculation of risk values can be either in nominal or real dollars, and can be discounted or undiscounted. It is recommended that for construction period risks, undiscounted values be used (they can be nominal or real). These values can then be integrated into the financial model and ultimately converted into nominal amounts.
For operating period risks, costs are typically presented as real dollars, making it logical to do the analysis in real dollars. These real dollars can then be integrated into the financial model and ultimately converted into nominal amounts also.
Once all the values are expressed in nominal terms, they can be discounted to determine their NPC and added up, allowing a comparison to be made between the two models.