Greenhouses have to be designed to not only capture solar technology but also adequately ventilate extra heat if Greenhouse Auto Vent 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 function really well because they are located where heat gathers naturally at the peak of the roof.
If vents in the roof are not possible, make sure to at least have a window to two you can open.
Ideally you need to have cross ventilation so two windows upon two sides of the greenhouse work greatest.
However you shouldn’t leave the vents or windows open at nighttime as you’ll lose any heat gain and cool your greenhouse too much.
So you close the vents or windows at night and what occurs the next morning: you forget! Today 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 plants suffer if the night time is too cool.