In California, the CEC requires the use of generic R-values for certain types of insulation. For example, spray polyurethane foam is R-5.8. However, specific brands of a given type of insulation may have higher R-values. If that can be demonstrated with 3rd party test data, can the higher R-value be used in the LEED modeling?
For the purposes of LEED for Homes it is acceptable for a home to model a home using product-specific performance attributes as long as those performance attributes are verified by a third-party (e.g. energy rater or Green Rater).This ruling is not in any way a substitute for state codes. The project may have to conduct duplicative modeling (for the state and for LEED for Homes) if it wants to earn credit, but state and local code requirements must be followed.