Thanks Bruce! Those were all great examples.
I remember seeing a DP use soft sources above windows some time ago and I love the look it gives. Sheer curtains and blinds are great for increasing the believability of a blown out window.
If you were to put a harder source through a window at night to create direct sunlight, what fixture would you use?
I would use a fresnel light powerful enough to get the desired effect. If you are shooting with a tungsten white balance in your camera, tungsten fresnels will be fine. I would avoid open faced lamps as they don't flag well for making shadow. At ISO 800, I think you'll find a 2k lamp is often enough, but it depends on the size of the set.
If you want to watch some clips... Towards the end of this reel there are interiors of the house (while under construction and when completed) that was shot on a stage with a large photo backdrop. We shot it all with tungsten lamps and I think it took 70 lamps to light the set (including lighting the backdrops)