FEATURESTORY
by Eric Hopper
The Future of Lighting for Greenhouses
and Indoor Gardens
T
he sun is the ultimate radiant energy source
and replicating it with an artificial lighting
system is not an easy task. In the horticultural
lighting sector, there is an ongoing quest to
best replicate the radiant power of the sun. We still
have a long way to go and this is why artificial lighting
technologies are constantly evolving. Due to our in-
creasing knowledge in plant physiology and the various
breakthroughs in the materials used to create artificial
light sources, we have witnessed much improvement
in horticultural lighting over the years. Although it is
impossible to predict the future of artificial lighting
for horticulture, there are some technologies that will
surely shape the future of horticultural lighting.
High Intensity Discharge (HID)
The future of horticultural lighting is sure to in-
clude some sort of high intensity discharge (HID) light-
ing. HID lighting systems have dominated the indoor
and greenhouse lighting sectors for many years. HID
lighting systems have changed and evolved many times
throughout the years. Currently, double ended (DE)
and ceramic metal halide (CMH) lighting systems are
shining examples of the most relevant lighting systems
of the future.
Double Ended Technology (DE)
Double ended technology, or DE technology, refers
to high intensity discharge lamps that are connected
12
at both ends. This is different from the traditional high
intensity discharge lamps that are connected at one end
with a mogul base. One of the biggest advantages of
DE technology is increased bulb longevity. A HPS lamp
burned at both ends will automatically utilize the com-
ponents within the bulb more efficiently. This results in
not only a long life span for the lamp, but also a better
overall spectral output (more PAR per watt).
Ceramic Metal Halides (CMH)
Currently one of the most efficient and effective
lighting systems available, ceramic metal halides are
already shaping the future of horticultural lighting.
Ceramic metal halide lamps contain an arc tube (much
like a HPS lamp), but also use a mixture of halides
and gases in the arc tube (much like a MH lamp). In
other words, a ceramic metal halide is almost like a
hybrid between a MH and a HPS lamp. CMHs are a low
heat signature lighting technology. Emitting less heat
equates to a more efficient light output and also re-
duces the need for cooling equipment, which, in turn,
increases an indoor gardener’s or greenhouse grower’s
overall return on investment. The heightened efficiency
and lower operating temperature are some of CMH’s
strongest attributes. However, it is the spectral output
of this technology that has piqued horticulturist’s inter-
est. Ceramic metal halides have a full spectrum output
and a color rendition index (CRI) rating around 90. The
sun has a CRI of 100.
www.GardenandGreenhouse.net
September 2018