The Automatic Vent Opener was designed to automatically control the temperature in all resin green Palram - Canopia Greenhouses. As the air inside the greenhouse warms, the vent gradually opens to allow the correct amount of air flow into the greenhouse and closes when the optimal temperature is reached. The vent arm was designed with the use of natural wax that expands as the air gets warmer, to push a piston which raises the window, then contracts as it cools, closing with the use of a spring. The Automatic Vent Opener operates without the use of electricity.