OK, I had another go at the interior lighting, but I’m not sure how successful that was. I created a new window wall and I used a plane with cell noise to simulate the curtains (the effect is not directly visible with this HDR because it doesn’t have bright sun). I’ve improved the rug hairs and did a couple more tweaks. Generally, I tried to go for a darker look that matches the lighting in my room right now (overcast autumn day). Here is a comparison: