Simple Box energy model requirements

What exactly is required to be submitted for documentation for the simple box model?  We see the worksheet and narrative listed as required documentation for this credit.  There is so much documentation required for the Optimize Energy Performance, but we don't see any specific documentation required for this credit and wonder what reviewers are requiring.  Also, if we decide to use the prescriptive approach for Optimize Energy Performance does that change what is submitted for the Integrative Process credit?