What would be a better material for a window?

Question

what would hold up to more stress

glass or acrylic

or something else?

Answer 1

clear perspex, if it's only to let light in and not to see in and out, you can get a bit of clear roofing panel instead

Answer 2

Glass is better than clear plastic. If the window is having to carry a heavy load there are two ways to improve its strength.

a) use thicker glass. One can find it easily at glasiers' shops but to fit it in an existing window frame may be difficult without some modifications to the frame.

b) use toughened glass. The way it is toughened is by heat treatment for which a special order with your glasier is necessary. The advantage of this is not only greater strength, but also when it does break it shatters into thousands of pieces, which are probably less dangerous than a few sharp edges.