Hello Fani,
Actually what you want exists and its called Xpresso.
Its a little more advanced, so you might need to carefully see it, in order to replicate it. (Its like nodes)
I have set up you scene like you requested. There is a cube in the scene named “Change States”.
1) When the cube is disabled its your 1st state. (closed doors and lights 50%)
When the cube is enabled its your 2nd state. (opened doors and lights 100%)
2) You will notice some extra files inside. Dont delete them.
The name 0.5 of the 1st null is the 50% intensity. By renaming it to 0.3, you will change the intensity to 30%. Also by changing the R. H., you change the degrees for your door. (0 degrees for closed door)
3) Also on the cube there is an expresso tag. If something breaks, it will deactivate.
If you have any questions please let me know.