system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why are WW2 era factories depicted as having a sawtooth style roof?

Did they really have roofs like that?  Why is this style popular?  What benefits are there to making a building like this?
gpt
Yes, they really had roofs like that.

The sawtooth design had the advantage of being a good way to get a lot of natural light into a big structure without letting in direct sunlight that would heat the building up too much.