Lights OnWhen creating renderings, it is desirable to have control over which luminaries are one and off. Revit provides one way in which to do this. Anytime a light fixture is selected in a project, the Options Bar shows the Light Group function as shown here.
When you select Edit/New... you get this Artificial Lights dialog shown below. Here you can...
create New groups; I like to include the room number to keep them straight.
Clicking Edit allows you to add and remove lights as shown here. In this room we might have the pendents in one group and the recessed cans in another. A light can only be in one group.
Now, in any 3D view you can open the Rendering settings and, if the Lighting is set to one of the artificial schemes, you can click the Artificial Lights... button. In the Artificial Lights dialog you can control both light groups and individual lights. This also includes a dimming option as shown in the next image. These settings only apply to the current view.
Unfortunately, other rendering tools do not take advantage of this Revit functionality - at least not that I know of. Perhaps it is not accessible via the API, which is how 3rd party apps are able to talk to Revit grammatically.
I was just chatting with someone from Singapore yesterday, via LinkedIn, who was asking about this. If you want it, like any other desired feature, be sure to let the developers know!
Some companies take new ideas via email while other have more formal ways. For example, similar to Autodesk's Revit Ideas page, Enscape has a Development Agenda tool via Trello. Getting involved in betas and providing constructive feedback is another great way to help steer development.
Interior Design Revit Book
I cover light fixture groups in my Interior Design Using Autodesk Revit 2018 book. The last image is a page from that book on this topic.