Where the simulation program does not model a design, material or device of the proposed design, an exceptional calculation method shall be used where approved by the code official. Where there are multiple designs, materials or devices that the simulation program does not model, each shall be calculated separately and exceptional savings determined for each. The total exceptional savings shall not constitute more than half of the difference between the baseline building performance and the proposed building performance. Applications for approval of an exceptional method shall include all of the following:
- Step-by-step documentation of the exceptional calculation method performed, detailed enough to reproduce the results.
- Copies of all spreadsheets used to perform the calculations.
- A sensitivity analysis of energy consumption where each of the input parameters is varied from half to double the value assumed.
- The calculations shall be performed on a time step basis consistent with the simulation program used.
- The performance rating calculated with and without the exceptional calculation method.