Could you tell us your methods of lighting? You have some really good renders.
You can create a point light and set its ‘Light Geometry’ to an option ‘Light Portal’ will appear under its light properties
Lack of lighting issues is that there is not enough light This is especially a problem if you are lighting your scenes with only an HDRI
You'll need other lights inside your room still and also make sure you have your rendering settings set to ‘Scene & Dome’ and make sure to enable the ‘Caustic Sampler’ in the Optimization section of the Render Settings and as for Emissive Windows this technique very helpful!
Turn your window into an emissive surface it is in view of the camera then it will appear white in most cases this would be correct darker interior lighting would cause the window to appear very bright and ‘blown-out’ to a camera or perspective view
there is a lot more amazing presets for indoor lighting this is the one I like the most
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I know it is a weird fetish and I dont really know if it is a fetish or not. 
