Posted: 29/10/2017 at 12:17
My polytunnel is clear plastic but has a green net mesh thrown over it to reduce light levels in summer. I have it in a spot sheltered from strong winds and chose a polytunnel for all the extra spoace I could afford plus ease of erection. In addition, in our Belgian garden we always had to replace glass panes in our greenhouse, every year.
I think, if you check prices, that, per square metre, polytunnels work out cheaper and also simpler to construct than greenhouses whether glass or polycarbonate. The only thing is that you may need to replace the polythene sheet every few years to maintain light levels but I believe polycarbonate also degrades over time and lets less light in.