Question-and-Answer Resource for the Building Energy Modeling Community
 | 1 | initial version |
The only way to take a file and move it to a previous version in EnergyPlus is to open the file with a text editor (such as Notepad++) and edit the file to conform with the changes between the two versions. I would open the Energy+.idd files for both versions in the diff utility (such as WinMerge) that shows how the file changed between the versions and also look at the transition rules that the EnergyPlus development team uses to document changes in input:
https://github.com/NREL/EnergyPlus/blob/develop/src/Transition/InputRulesFiles/Rules8-6-0-to-8-7-0.md
With those resources, it would be possible to modify an IDF file so that it could be opened in a previous version.
It would probably be easier to just start using EnergyPlus 8.7.
