Last summer I visited my folks back in New York City. My sister just had a baby, so I setup a quick “studio” in her then-spare bedroom for a photo shoot of her, my brother-in-law and their new boy.
The room walls were painted in light blue color, which was also the color of the window drapes. This gave me a nice background to work with. I put together a couple of light stands with tungsten bulbs to contrast nicely with the cooler background, and set everything up by the window. The sunshine streaming through the blue curtain of the window provided a well-illuminated background, which thus didn’t require a separate illumination.