Elaine, I did cut windows in the plastic in Spring, just like you said, on three sides, and then rolled the plastic up. I had this set up in zone 5a in Utah, so there were no windows needed or wanted during winter. If it got a little too warm, I'd just roll up some of the plastic along the bottom during the afternoon and opened the door, and would then unroll it and cover it back up with dirt when it started to cool off. I never had any problems with algae or mold. Utah is very arid, so I'm sure that everyone would need to figure out what works best for their area. We've recently moved to Idaho, and it is a little more humid here, and warmer, so I'll have to see what happens this year.
Thanks for adding that very useful information!
