Method to report proposed case Energy consumption - On site Gas Engine based electricity generation

It sounds like the reviewer is trying to get the prerequisite form to correctly show the savings. For CHP systems in the proposed model you include the gas consumption of the CHP plant associated with this project and then you subtract the electric production associated with this project. Most the more recent forms won't allow you to enter a negative number in the modeling results table so the reviewer is suggesting you enter it in the exceptional calculations area which does allow negative values.

That benefit should be captured within the Proposed energy modeling results. The Proposed model should include the gas consumption of the CHP and the waste heat benefit. You record the gas use as a plus (that is what the CHP is consuming) and the electric production as a minus. Sorry for the confusion here but when you enter values into the exceptional calculation a negative entry reduces savings and positive entry improves savings. So there are two ways to do this - you can include the CHP impact in your proposed model and enter the electric production only in the exceptional calculation or you can model the proposed without the CHP, entering those results in the form, then run the proposed with the CHP and enter the difference in the exceptional calculation. The latter is preferred since the reviewer can clearly see the isolated savings associated with the CHP. In this case you would enter the electric production as a savings, and you would have both negative and positive gas consumption. Be sure to account for all the differences in the results between the two models.

That is what we would do. Make sure you provide a thorough narrative explanation for what you have done and how you did it.