lower greenhouse temperatures by as much as 10 to
20 degrees below the temperature outside. Evapo-
rative coolers require a tightly sealed greenhouse;
gaps must be sealed to ensure it works with the
highest effi ciency. The pads have to be cleaned and
treated for algae, water quality has to be maintained
and fi lters have to be cleaned and replaced. How
long an evaporative cooling system lasts is deter-
mined by how well it is maintained.
The advantages of using an active system are
having precise control, as well as avoiding drafts
and potential plant damage along the outside edges
of the vents. Syncing ventilation equipment up to
a greenhouse controller allows growers to create
detailed equipment schedules with almost no labor
required. With a controller, a grower can manage
humidifying and dehumidifying equipment, like
exhaust fans, with the fl ip of a switch or by au-
tomating the system to respond to environmental
changes. Controllers can even be fully integrated
with other atmospheric controllers and timers. Hav-
ing more precise control allows growers to extend
the growing season or create a year-round growing
operation. It is wise for growers on strict delivery
schedules to opt for active systems, because the
added element of control allows them to more easily
achieve optimal growth.
As an added bonus, active ventilation also limits
the entrance of pests, since they are relatively sealed
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www.GardenandGreenhouse.net
June 2018