SPONSORED BY: EDITORIAL DIGEST LED-based horticultural lighting plants the seeds for successful grow operations Solid-state lighting (SSL) technology delivers control and tunable spectrum benefits that can enhance and improve plant growing operations, especially in new operations outside of the typical farming community. This editorial digest combines the latest information on science-backed horticultural studies, a close look at photometrics and energy-efficiency criteria for horticultural lighting, and a detailed insider’s guide to comparing and selecting appropriate fixtures for project specification. 2 LED efficacy, UV, and plant feedback highlight horticulture presentations 12 Understand energy efficiency of LED horticultural lighting systems 21 Buyers benefit from LED grow light guidance Reprinted with revisions to format from LEDs Magazine. Copyright 2018 by PennWell Corporation
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
SPONSORED BY:
EDITORIAL DIGEST
LED-based horticultural lighting plants the seeds for successful grow operationsSolid-state lighting (SSL) technology delivers
control and tunable spectrum benefits that
can enhance and improve plant growing
operations, especially in new operations
outside of the typical farming community.
This editorial digest combines the latest
information on science-backed horticultural
studies, a close look at photometrics and
energy-efficiency criteria for horticultural
lighting, and a detailed insider’s guide to
comparing and selecting appropriate fixtures
for project specification.
2 LED efficacy, UV, and plant feedback highlight horticulture presentations
12 Understand energy efficiency of LED horticultural lighting systems
21 Buyers benefit from LED grow light guidance
Reprinted with revisions to format from LEDs Magazine. Copyright 2018 by PennWell Corporation
* This article was published in the February 2018 issue of LEDs Magazine.
LED efficacy, UV, and plant feedback highlight horticulture presentations
The second US Horticultural Lighting Conference was packed with informative presentations, reports MAURY WRIGHT, with prevailing themes including SSL comparisons with legacy lighting, the use of ultraviolet spectrum to boost secondary metabolites, and the future of horticultural lighting.
IN DENVER, CO on Oct. 17, 2017, many of the foremost experts in the area
of horticultural lighting gathered at LEDs Magazine’s second annual US
conference on the topic. The day was packed with informative talks and
the networking in the tabletop exhibits and at the evening reception was
fast and furious. Here we will highlight a few presentations that looked at LED
lighting relative to alternative light sources for plants, ultraviolet (UV) lighting as
a way to sculpt the flavor or potency of cultivars, and future efforts that might
take feedback directly from plants to control the lighting applied.
Before we get started,
we will suggest that you
peruse some past content
if you aren’t familiar with
the concepts that underlie
FIG. 1. Petunias exhibit differences when grown in a greenhouse under no supplemental lighting (left), HPS supplemental lighting (middle), and LED lighting (right).
LED efficacy, UV, and plant feedback highlight horticulture presentations
3
LEDs Magazine :: EDITORIAL DIGEST :: sponsored by
LED-based horticultural lighting. An article that we ran last year examined solid-
state lighting (SSL) in the horticultural role, and contemplated key metrics that differ
from those used in lighting for humans. And coverage of our 2016 Horticultural
Lighting Conference provides insight into many issues surrounding the burgeoning
application. Moreover, Philip Smallwood, director of research at our Strategies
Unlimited market research business, opened the conference looking at the challenges
of the application and at
market data. For a limited
time, a webcast that reprised
that presentation is viewable
on demand.
The keynote presentation in
the opening session at the
conference came from Steven
Newman, the greenhouse
crops extension specialist
and professor of floriculture
at Colorado State University
(CSU). Newman had been
given a unique opportunity
to oversee construction of the
new CSU Horticulture Center
a few years back when the university built a new football stadium on the site of the
old facility. The project included more than 21,000 ft2 of greenhouse space, more
than 6000 ft2 of classroom space and a 6-acre outdoor gardening area.
As the new facility was being planned, Newman described how a chance meeting
with Philips Lighting led to the greenhouse facility being equipped with LED-
based Philips GreenPower Toplight luminaires despite the fact that Newman had
no prior SSL experience.
In spite of objections from the university engineering department that also had
no experience with LED lighting, Newman went forward with the SSL installation
based on the economics. Newman offered the data in the nearby table at the
conference, where the projections indicated that LED lighting would cost a half-
FIG. 2. Peter Barber of SETi explained how UV lighting can impact the production of secondary metabolites in plants, affecting flavor and other qualities.
LED efficacy, UV, and plant feedback highlight horticulture presentations
5
LEDs Magazine :: EDITORIAL DIGEST :: sponsored by
cent per day per square foot to operate and the high-pressure sodium (HPS)
alternative would cost more than a cent and a half. Newman said, “That tells me
the return on investment is faster than you think.”
LEDS AND FLORICULTURE
Newman said he welcomed
the next phase of his career
as a chance to learn about
working with LEDs and set
about to study “What could
we do with floriculture plants
to speed the production?”
Newman said he has already
studied a number of bedding
plants, but described one set of
tests in particular that directly
compared 600W LED lighting
with 1000W HPS lighting. He
said the HPS lighting delivered
PAR (photosynthetically
active radiation)-band PPFD (photosynthetic photon flux density) of 65 μmol/m2/
sec compared to 84 μmol/m2/sec for the LED lighting - with variables such as bench
height, temperature, and on/off cycles for the lighting held constant. Newman took
measurements at night to ensure that the PPFD levels were accurate with only a
security light providing in the range of 0.47 μmol/m2/sec in stray light.
The cultivar studied was the Bada Bing Scarlet variety of begonia. Newman
showed side-by-side photos of plants grown with no supplemental light, with the
HPS supplemental light, and with LED supplemental light. The plant that was
grown with HPS light was considerably smaller than the other two. Newman
classified it as suffering from “stunting.” He said he could not explain the
impact for sure, but speculated that it may have been due to the spectral power
distribution (SPD) of the HPS lighting.
The plants grown with no supplemental lighting and with LEDs appeared about
equal in height. But the plants grown under the LED lighting appeared more dense.
FIG. 3. LESA’s Tessa Pocock projected a future in which sensors would enable a closed-loop system for horticultural lighting where plants would tell the system what they need.
* This article was published in the April 2017 issue of LEDs Magazine.
Understand energy efficiency of LED horticultural lighting systems
The true efficacy of LED fixtures for horticultural lighting depends on many factors, explains JOSH GEROVAC, and lighting manufacturers and growers need to take a broad view to ensure optimal yields and energy efficiency.
THERE ARE MULTIPLE considerations that a business faces when
evaluating light sources to use for horticultural lighting, including
but not limited to: light intensity, spectrum, uniformity of light
distribution, energy efficiency, and fixture lifespan. Horticultural
lighting systems convert electrical energy into light that plants use to drive
photosynthesis for growth and development, and LED-based sources can offer a
spectrum tuned for the application. Still, ascertaining the efficiency or efficacy
of such solid-state lighting (SSL) systems is a challenge. There are several factors
that impact the overall efficiency of a lighting system, relative to the specific
application at hand. This article will discuss how the design of a lighting fixture
FIG. 1. The ability to deploy lighting solutions within inches of a crop canopy is a breakthrough for vertical farming applications. Properly designed LED solutions enable higher yields per square foot compared to poorly designed LED solutions and other lighting technologies such as HPS and fluorescent.
Understand energy efficiency of LED horticultural lighting systems
16
LEDs Magazine :: EDITORIAL DIGEST :: sponsored by
compared to HPS fixtures limited the transition
to SSL despite comparable efficacy.
LED chip manufacturers have improved the
efficacy of components available to horticultural
lighting manufacturers over the last several
years, which has enabled them to significantly
improve photon efficacies that now surpass HPS
fixtures, and they continue to improve every
year. Indeed, LED-based horticultural lighting
systems are now capable of achieving photon efficacies 45% greater than double-
ended HPS fixtures. While the improved efficacy of individual components has
improved the efficiency of LED-based horticultural lighting, it is also just one
variable responsible for the improvement over HPS technology.
LED system thermals
There is a common misconception surrounding LED lighting when it comes
to heat produced by the fixture. Many growers believe that LEDs produce less
FIG. 3. Harsh and dirty environments such as those in greenhouses can quickly cause active cooling systems to fail, and in turn, cause the entire lighting system to fail. In addition to improved energy efficiency, passive cooling systems do not require moving components prone to breaking and clogging.
Understand energy efficiency of LED horticultural lighting systems
18
LEDs Magazine :: EDITORIAL DIGEST :: sponsored by
While red LEDs have the highest photon efficacy,
plants did not evolve in nature under narrowband
wavelengths. So red LEDs alone don’t produce the
most efficient spectra with regard to optimizing plant
growth and development. This is especially true in
situations where lighting systems are used for sole-
source lighting as in vertical farms, as compared to
supplemental greenhouse lighting (Fig. 3).
Several horticultural lighting manufacturers
market their products’ “special spectrum” based
on the absorption peaks of chlorophyll a and b;
however, they fail to mention that those chlorophyll pigments are extracted
from plant leaves and measured in vitro. The action spectra of light quality on
photosynthesis (Fig. 2) was created from research that was conducted in the 1970s
by Drs. McCree and Inada, which showed while there is a correlation between
photosynthesis rates and the action spectra of chlorophyll a and b, they are not
FIG. 4. The spectrum (i.e., color) of light emitted from a horticultural lighting solution has a significant impact on both energy efficiency and overall plant growth and development. While red and blue light is more energy efficient to produce, a broad spectrum achieved with a light engine such as the one pictured will target more photoreceptors for improved cultivation.
* This article was published in the June 2017 issue of LEDs Magazine.
Buyers benefit from LED grow light guidance
With LED-based horticultural lighting on the rise, specifiers and end users need education to select the optimal fixtures for projects. RYAN MITCHELL and CHARLIE SZORADI deliver a guide to navigating spec sheets and performance calculations for best results.
THE EARTH’S POPULATION is projected to reach 10 billion by 2050, and
there are growing concerns about water, energy, and food availability
for such a high number of people. To maintain our current water
supply and produce enough food to feed our fellow human residents,
several different practices must
be adopted within the agricultural
sector. One potential solution to
the problem is growing vegetables
in water through hydroponics,
aquaponics, or aeroponics. LED-based
horticultural lighting works as an
excellent companion technology to
enhance crop production for indoor
applications, especially in warehouses
- in what is known as vertical or
urban farming - versus greenhouses.
The three water systems are soil-
less methods of agriculture that
can produce 5× the amount of food
in the same space as typical outdoor agricultural methods. Furthermore, these
practices utilize at least 90% less water than the irrigation practices used in
FIG. 1. Sample linear LED grow light modules with different color diodes on each module.
The educational benefits when using advanced agriculture systems with grow
lights are immense. Science, technology, engineering, and math (STEM) is
a focus point of many K-12 schools and universities in the US and beyond.
Hydroponics, along with other systems like it, incorporates all aspects of
STEM, which makes it a highly
effective tool to utilize in schools.
With the lighting, students
can learn about how different
wavelengths are optimal for
photosynthesis for different plants.
They can also build their own
systems from scratch, which forces
them to understand how the water
will flow, maintaining pH and
water temperature, and monitoring
the electrical conductivity (EC)
rating which reveals how much
fertilizer salts are in the water.
These experiments will be
highly engaging for students and
provide an excellent way to better
understand the science behind
these agricultural systems.
Another major benefit for
utilizing hydroponic, aquaponic,
and aeroponic systems in
combination with horticultural lighting in school is the potential nutritional
value - especially in inner-city schools. In many cultures, children are
becoming more susceptible to becoming overweight and obese, and it is
crucial for students to have better nutritional options available. By having
an agricultural system placed in a school, fresh vegetables can be readily
available to students. Furthermore, the vegetables being consumed would
come directly from the hands of the students. This will make it much more
Produce grown in-house at educational facilities using indoor agricultural systems that leverage LED horticultural lighting could deliver both a learning opportunity and improved nutrition on campus for students.