Revit checks for updates each time you click Run Energy Simulation or Results & Compare on the Analyze tab.
When you use Energy Analysis for Autodesk® Revit®, the latest updates for energy analysis reports are automatically installed while Revit is running.
To disable the automatic updates, edit the Revit.ini file to add the parameter "CEAAlwaysAutoUpdate=0" to the "[MISC]" section of the file.