Greenhouses need to be designed to not merely capture solar energy but also adequately ventilate extra heat if temps get too hot.
You should always make sure you have sufficient vents in the roof of your greenhouse as heat rises and you want that heat to flee.
Greenhouse roof vents function really well as 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 screen to two you may open.
Ideally you wish to have cross ventilation so two windows on two sides of the greenhouse work best.
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.
And that means you close the vents or windows during the night and what occurs another morning: you forget! Now 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 vegetation suffer if the night time is too cool.