Hard to say as it depends on your exact scene and the look you want to achieve. The image you posted is actually a great example. Look at where the lights are in that and sort of copy it. A decent night time HDRI might do the job, especially if you have a lot of windows. Or a very bright light to simulate the moon (same as in the loft image). If areas are still too dark after that you could put some small, dim lights dotted around those areas. That also depends on if you want moonlight only. But ultimately the best thing you can do is muck around with tone mapping, either as it renders or after. This can drastically change how an image looks and can bring life to a dull scene, make lights brighter and details clearer. I can't tell you which settings, so you'll have to muck around with them. Good luck.