Considerations for Legacy Codes[LINK]
Those module developers who are adding to EnergyPlus’s capabilities by adapting existing codes into the module structure should take special considerations.
First and foremost, who owns the legacy code that you are adapting? More on this is covered in Appendix C – Submissions and Check-ins. One must be very careful when developing modules to be implemented in the publicly-available version of EnergyPlus.
Legacy codes will typically come with their own input and output structures. In adapting a legacy code to use with EnergyPlus, the module developer will usually want to bypass these routines by embedding the code into EnergyPlus and using input entirely from the IDD/IDF structure. During original transition, you can consider doing a parallel effort of writing a simple input file for the legacy code while testing results with your developing EnergyPlus transition code.