Monet was 76 when he decided he needed a new studio. This one is actually the third one he built on the premises.
After having turned a former barn with western light into his first studio, errected the second one with a big window on the northern facade, Monet decided he wanted the light to fall from the sky, and not from any other direction.
This is why the third studio has huge skylights. The entire roof is made out of glass.