Using Lighting Scenarios
To use Lighting Scenarios in your UE4 projects, you will need to do the following:
First go to Window > Levels to open up the Levels Manager.
With the Levels Manager open, right-click on a Sub level in the Levels menu, go to Lighting Scenario, and select the Change to Lighting Scenario option to make the level a Lighting Scenario level.
When a Lighting Scenario level is visible, its Lightmaps will be applied to the world.
Make sure the Level Streaming method is set to Blueprint by right-clicking on the Sublevel, going to Change Streaming Method, and selecting Blueprint (if it's not already selected).
Now place any light or Static Meshes your project needs into either of the lighting levels and then build each level's lighting as you would with any other level.
Once the lighting has finished building, open up the Persistent Level's Blueprint and then add a Load Stream Level node, connecting it to the Event Begin Play node.
Connect the Event Begin Play node to the Load Stream Level node and then input the name of the Level you want to load. Also, make sure to check both Make Visible After Load and Should Block on Load to make sure you can see the newly loaded level.
Press the Play button to launch the project and when the first level loads, it should now be using the Day level lighting. To use Night level lighting, you can use the same setup, but you'll need to change the level name to your night time level (instead of the day time level).
Although there are some notable limitations, using Precomputed Lighting Scenarios in UE4 can provide your project with many benefits; such as improved performance and the ability to change to baked lighting (to meet your project's needs).