On Blender 2.80, lights (other than the sun) have various options for their strength. By default there is Power, measured in Watts, and a color option. If you enable "Use Nodes" you also get a generic Strenght value and another (seemingly ignored?) color option. I know that the Size option doesn't affect how much light is emitted, but just from where and also the shadow penumbra/softness.
But which value should I use when I set the power of my lights? For example, I have a simple scene with two area lights (30m in size), at the default power they were too weak to light the objects I have placed in the scene (it's a smoke simulation). I had to increase the Watts to 100000 to get the a good lightning. The lights weren't very close to the object, but not too far either.
1000W with 1 in Strength is quite a faint light. 10W with 1000 in Strength is very strong instead.
Is Strength basically just a multiplier? Which means that the light emits 10.000W?
Which one should be used? Or how should I use both to get a "correct" (as in physically correct) result? Also does scale impact the amout of light? I usually set blender to centimeters instead of meters, because I use it with UE4 and UE4 uses centimeters as the unit.
Here is my blend file: https://we.tl/t-n4dS51e9AP