Under Control - 2019 - 16

Minimizing Greenhouse
Energy Loss
As energy costs continue to rise, growers to need to know what their options are to
help reduce energy inefficiencies to grow healthy crops and maximize their profits.
By Dean Peterson
Solar power, also known as
photovoltaic (PV) systems, LED
lights (light-emitting diode) and
infrared heaters are all some of the
technologies being looked at as ways
to reduce greenhouse energy costs,
whether it is for growing CEA crops
or floriculture crops. But the first step
in any investment is to reduce any
existing energy inefficiencies in your
greenhouse.
That's the message from Heidi
Lindberg, Michigan State University
(MSU) greenhouse and nursery
educator. Lindberg offers these tips on
improving energy efficiency.
Manage the temperature based on
the crop and finish date. " Do I grow
the crop cooler for a longer period of
time or warmer for a shorter period
of time? It saves energy to grow at a
warmer temperature for a shorter time, "
Lindberg says.
Close air leaks. Seal vents, doors and
fan openings with weather stripping,
and cover exhaust fan openings when
not in use. Fix any tears in the poly and
replace any cracked or missing glass
panes. " Close up those leaky spots in
the greenhouse, " Lindberg says. " You
don't want energy savings to go out of
the door or out of the poly. "
Horizontal air flow fans help mix
the air in the greenhouse and can
help keep temperatures uniform. The
fans also mix the humidity and CO2
Consistent air temperature throughout
.
16
the crop will ensure the crop grows as
uniformly as possible.
Install infrared (IR), anticondensate
poly film. The IR film
treatment lets sunlight in but traps the
radiant heat inside the greenhouse. The
anti-condensate treatment reduces the
surface tension on the poly allowing
condensation to flow down the poly
and not form droplets. " You don't have
as many drops of condensation on
the underside of the poly, " Lindberg
remarks. The droplets can block
sunlight, drip on plants and workers,
create an environment conducive for
pathogens and create safety issues such
as slippery algae on the floor.
Use photoperiodic lighting on longday
plants. Long-day plants flower
when the dark hours fall below their
critical photoperiod. Properly timed
supplemental lighting can artificially
reduce the number of nighttime hours.
" You use photoperiodic lighting to
induce flowering, " Lindberg says. " The
goal is to grow a quality plant as fast as
you can. "
Incandescent lamps alternating with
compact fluorescent lamps are effective
for stimulating flowering of long-day
plants. LED lights can also be used to
regulate flowering by photoperiodic
lighting, but choose the LED lights
carefully. LED lights are a major
investment and there are many LED
lamps available. Their light spectrum
varies and sometimes causes confusion
on how to use them. You need to
be careful about what you're using,
UNDER CONTROL: TIPS FOR CONTROLLED ENVIRONMENT GROWING * 2019
Lindberg says, and check out some of
the resources that are available.
Use high-intensity light on young
plants. " High-intensity lights are most
economical for growing young plants
because you have so many plants per
square foot, " Lindberg says.
Transplant larger plugs and liners.
Plants in larger plug trays take less time
to finish growth, but larger plugs do
cost more.
Use more energy-efficient heaters.
Some heat is always lost with the
exhaust gases, but more energy efficient
heaters lose less. " The most efficient
heaters for greenhouses have up to 96%
thermal efficiency, " Lindberg says.
Insulate side, knee and end walls.
Whenever the temperature in the
greenhouse is different than the outside
air, heat energy will move through the
Under Control - 2019

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