p3taoctane wrote:
How does one increase the portals strength...
So far I never used portals and I did not test 2.48. Nevertheless I'm pretty sure, that it would not be useful to change the "strength" of a portal.
As I understand radiance explanation, portals are only guides for the render-kernel through the geometry of the scene.
So everything should work as in the same scene without any portal. The only difference should be, that you need less samples to get a noise-free picture.
If this is correct, than of course the inside becomes brighter when you increase the daylight power and there is no need for a portal strength. A portal should be pure geometry as I understand it.