Greenhouses need to be Greenhouse Auto Vent designed to not merely capture solar energy but also adequately ventilate excess heat if temperatures get too hot.
You should always make sure you have adequate vents in the roof of your greenhouse as heat rises and you want that heat to flee.
Greenhouse roof vents work really well as they are 
located where hot air gathers naturally at the peak of the roof.
If vents in the roof aren’t possible, be sure to at least have a screen to two you can open.
Ideally you want to have cross ventilation so two windows upon two sides of the greenhouse work greatest.
However you should not leave the vents or windows open at nighttime as you’ll lose any heat gain and cool your greenhouse an excessive amount of.
Which means you close the vents or windows during the night and what happens another morning: you forget! At this point your greenhouse overheats and if you’re unlucky, you lose some plants.
Or you forget to close the vents at nighttime as well as your plant life suffer if the night time is too cool.