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 adequate vents in the roof of your greenhouse as heat rises and you want that heat to escape.

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 aren’t possible, ensure that you at least have a windowpane to two you can open.

Ideally you want to have cross ventilation so two windows on two sides of the greenhouse work greatest.

However you should not leave the vents or windows open at nighttime as you’ll lose any kind of heat gain and cool your greenhouse an excessive amount of.

Which means you close the vents or windows at night and what happens the next Greenhouse Auto Vent 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 plants suffer if the night is too cool.