Well, i can inly hope that thread is monitored by developers...
So, shat is want is the portals which can work as light intensity multiplier.
That's the way it is in Redshift, and it seems pretty convinient - you can light large interiors (i had some projects with large warehouses) without going crazy on power slider in HDRI environment.
The interior will be lit as user wants, and exterior details will be visible as well.
It's cool, i guess