Use a ventilation system to automatically protect your greenhouse plants from withering heat build-up. No need to daily open and close vents, trying to out-guess the weatherman! Let a thermostatically controlled system do all the work. The thermostat turns the system on at the temperature you select. The fan expels hot air and fresh, cool air is drawn in through the shutters. A fan speed control enables you to adjust the amount of airflow to suit the seasons. A motorized shutter is wide open when on and held closed when off. Select one of our ventilation systems or build your own system from components. Caution: A fan system alone cannot completely cool a greenhouse. Shading is also required. Additional cooling is possible with a misting system or evaporative
Install shading to shield the greenhouse or sunroom between 9 a.m. and 5 p.m. Severe western exposure may require shading until 7 p.m. Shading should cover the roof and at least the upper half of the south wall. The amount of shading needed varies depending on your local climate, greenhouse design, and light requirements of your particular plants. Use the least amount of shading necessary, because excessive shading can slow plant growth or cause plants to “reach” for more light.
Ventilation and shading will prevent the greenhouse from seriously overheating, but it is the evaporation of moisture inside the greenhouse that will maintain a comfortable temperature. Evaporating water soaks up heat like a sponge because heat is used when water changes from a liquid to a gaseous form. Good air circulation from fans increases evaporation. The amount of moisture necessary to cool the greenhouse will vary considerably depending on the amount of ventilation and shadingRead more on backyardgardener.com