I stumbled on this brief article while looking through this solarpunk blog. On the farm I worked at growing up, all but one of our greenhouses were plastic stretched over a metal frame. We replaced the plastic fairly often (I'm not sure how often - I know I helped do it more than once, but probably not for the same greenhouse) due to sun and wind damage. The old plastic was pretty useless at that point unless you needed a dropcloth with some cracks in it, so it usually went in the dumpster and then to our local landfill.
It sounds like these folks soaked some sort of fabric in beeswax, and I'm curious how well that holds up. Certainly it'll need replacing at some point, but so did the plastic, and at least the textile and wax can be composted eventually. Does anyone have any experience with this?
You could try looking up durability of waxed canvas. That has been a material used for centuries (millenia?) for tents and bags. A couple minutes of searching didn't yield immediately useful numbers. Some sites say waxed canvas can last decades. However, I think that's in context of bags which would only be exposed to the elements part of the time. One bag maker suggests that wax has to be reapplied every year or two. I found a research paper that demonstrates significant deterioration of beeswax with nitrous oxide and UV exposure. Clearly a greenhouse is going to have plenty of UV exposure. I'm not sure how to translate their numbers into a maintenance interval though.
So my mostly uninformed opinion is that this is good in that the materials are all biocompatible and renewable (if a plant based textile is used), but I would expect it to need regular reapplication of wax.
Glass would be longer lasting, but likely more expensive.
I wonder if something like natural rubber on a thinner material would work better
I believe natural latex requires substantial uv stabilizers to not degrade in sunlight, but i suspect uv stabilizers would negatively affect the spectrum of transmitted light.
Silicone soaked fabric is sometimes used for tents, but I guess that wouldn't be biodegradable then.