When I clicked the 'calculate' button in my REVIT MEP Heating and Cooling Calculations the calculation process kind of just hung there.
So after a little investigation I learned that there was a 3rd party (IES) that was not working properly.
After running the installation from the link below and restarting my REVIT MEP it all worked beautifully.
Below is the IES installation link:
Here's a snapshot of the cool report that it generates.