Do glass roofs protect Sims from the elements?

I had a room that was a solarium so I used the glass roof (without a ceiling underneath), and had full glass windows on the walls of that area.

I've been told that not having a ceiling over a roofed area could cause the Sims of players that have Seasons installed to freeze to death (although I'd never had this happen in the houses I built).

Since the purpose of the glass ceiling is to just provide light/view of the sky, then it seems that it would also serve as a ceiling thus you could create a solarium without exposing your Sims to the elements.

Does anyone know if the glass roof acts as a ceiling also?