Use a ventilation system to automatically protect your
greenhouse plants from withering heat buildup. No need to manually open
and close vents, trying to outguess the weatherman!
Choose non-electric Solar-Powered Vent Openers (see Vent
Opener and Design Guide) or choose an electrical thermostat controlled
fan system for worry free operation. 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: Ventilation alone cannot completely cool a
greenhouse. Shading is also required. Additional cooling is possible with
a misting system or evaporative cooler.
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 evaporation of moisture inside the greenhouse
that will actually 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 shading provided, your local
climate, and daily weather changes.