Best breathable fabric that holds up outside all day without degrading?

Hi folks, this isn't exactly fashion, but this group seemed like the best ones who might know the answer to this question?

I want to make a shade sail around my AC unit. Similar to this product[1], but with sustainable/natural fabric. What kind of fabric would be best for this, since it would need:

- To hold up under direct sunlight for at least a couple years (if I have to replace the fabric every 2-5 years, that's preferable to 10 years with their polymer version)

- Not absorb too much water that it becomes extremely heavy in the rain

- Block/reflect UV/IR heat from sunlight

I was thinking maybe Linen coated in linseed oil maybe?

[1] https://www.kickstarter.com/projects/438361791/ac-shade-increase-air-conditioning-efficiency/description