Hi. Have you tried with a value higher than 10? (maybe 100 or 10000).
Yeah, i predict that your light should become white again at slightly above 30 units of intensity, 32 to be exact ;]
This I true, although this is not the desired effect.
Maybe it’s easier just to show what I’m trying to accomplish.
I’m trying to get this effect.
The furthest I got (see attachment) is where I put a self illuminating material on the fluorescent lights to get a bit of light/shadow effect on the tubes them self, and put a big cylindrical corona light over the whole pillar to get a good lighting effect on the surrounding. But this doesn’t look quit right. I think I’m doing something wrong here and that it’s probably the way I’m trying to recreate this is wrong.
Does anyone have a better Idea?
And how you want to achieved this with large windows and day light? Also are you trying to set exposure(-5) for daylight in interior?
exactly, both questions: Yes
So what exactly you don’t like in your last example?
In my last example the lights don’t really look like lights, It looks more like white tubes. I tried a bit of bloom on the image but the white plane in the background gets way more of a light effect then the fluorescent tubes them self.
Hi Jens. If you look at your reference picture, you can see the armature behind every light - giving some contrasting background to the light, as well as spreading indirect light. In your model there’s nothing behind the lights. They are sort of “floating” freely in space without depth.
I would model them more realistic to give a more realistic look, and I probably would make each tube as a light, instead of one big surrounding light tube.
Also turn on glow and glare. If used right, it can do wonders to your lights. Just don’t overdo it - small amount (1-2 px) of glow is more than enough to make look lights more realistic.
JensH - it is easy to do it. But its not if you do not have experience.
If you want to create something as realistic as possible it will not be that easy and simple. 
How I would do this is:
First of all have a good model of your light tube to make it as real as possible. Not just a cylinder and you are good to go.
Create realistic materials for the tube.
Put A tube cylinder shape corona light inside of the glass tube, but do not make it in full lenght of the glass tube. THE ENDS have to be darker to make it more realistic, because those end are the connections, joints of the real light unit.
Select that light which is inside press INCLUDE and include only tube light model (all of it) + Your concrete column. Nothing else. You will be able to control that tube light intensity only for the tubes excluding the whole scene. In this way if the light from the exterior is to bright you will still be able to control the tube lights separately not to over burn them.
Now obviously these tube lights will produce light from them to your interior. So Crete a CAPSULE/cylinder shape corona light and place it around the concrete column with your tube lights. PRESS exclude - choose your column and your tube lights. With this light you will control the light coming from the tubes to your interior. Not effecting the column and tubes. Because you will be effecting tubes with their inner lights.
Control your exterior lights not to over burn everything in the scene.
Make a MAT ELEMENT OR MAT ID for the glass tubes. In post you will be able to reduce them or bump them up if needed.
OR SCRAP all of this and use Self Illuminated material in the tubes for faster rend-times.
With these tricky lighting setups it will be always tricky. But if you know what you are doing it will be fine. And the rendering times and noise will work better with your scene.
Because now if you would just put a light in those tubes and just pull the intensity up it would be a disaster Because that light will have to go throw your tubes into your scene causing longer render times and more noise. It will be hard on the engine and blablabla bla.
In the end this is my personal opinion you can do it whatever way you think is best for you
Good luck.
Thanks everyone for the input, This is my first time posting something on the this forums and it’s very friendly and helpful here.
I think I found the effect that I need (see attachment). I do need a beter model with probably less tubes to let it look realistic, but I’m not the one designing it. But still a better model is certainly the next step.
I included screenshots for the material setup to if anybody’s interested.
