I want to tell you about my method quick render of the interior.
1. item - I do HDR environment map + Octane Light === the sun
2. item - I will include Sample Evvirometn
3. I do a render without Diffuse - only use Direct
4. I do a render Diffuse - Indirrect diffuse = the material of the walls I do transmition =1
all-light OFF - scene - ligth = HDR or white color
(why I do not consider path tracing - when in the scene a lot of glass it is not profitable)
5. composing - direct + indirrect (screen)
6 + AO
this method works quickly when a lot of light sources and a lot of glass and light sources are inside the glass.