We have a feature request in for this that is logged with UE-10034. At the moment this is backlogged though, so there is no ETA for when/if this will be added to the engine.
There is a work-around way of doing this that may help for the time being. I would consider this a “hacky” method, but it’ll work in this situation.
- You can setup a sub-level by going to to Menu > Window > Levels.
- Create new level and name it.
- right click on the level and set the streaming method to “always loaded”
- Select the objects that you want to exclude from the light build
- Right click on the level in the Levels window
- Select “Move Selected Actors to Level.”
- Hit the EYE next to the level in the Levels window to hide anything from that level
At this point, when you build lighting since everything in that level is not loaded it will build without those assets.
There are some caveats to this though. If you place lights in hidden levels like this, there will be some bleed between the two depending on the brightness, radius, and other lighting settings. This is not a method to block lighting from being baked between levels, but it can work to exclude assets from your lighting build if you need to check a larger scene more quickly for whatever reason.
I hope this helps.