How do you control the temperature of a greenhouse?

The temperature in a greenhouse is affected by the ventilation and the amount of sunshine it receives. Greenhouses are designed to trap the heat from the sun. If nobody changed anything, the temperature would keep rising until the sun went down. Temperature can be controlled by opening the door or opening vents in the roof. In extreme cases, air conditioning could be used to bring the temperature down to a more reasonable level. Good luck!

Fans with vents to cool and heaters for winter. You can also use sun block, that comes in varying degrees

Here in Texas, Sun Screens and Ventilation are key in the Summer. I'm into Aquaponics so the 'Water' offers a natural way to moderate hot temps. An indoor waterfall may also offer not only heat moderation but water aeration for both the plants and fish. Use Solar water heating with a heat exchanger and same ventilation system in the winter to moderate the cold.

We had a greenhouse when I lived in Texas. The best thing I found was something called shade cloth. In the mornings I would throw the shade cloth over the greenhouse. That shaded it and kept the hot day time sun out. Also found it helpful to use fans and windows to help also.

If you put your water on a homemade sprinkler system and water in the morning the added humidity helps keep the temp down also. And this makes watering as easy as turning a handle.