Scientists say that light at certain spectral levels is more helpful to chlorophyll absorption than others, according to LEDs Magazine. Thus, LEDs – in which spectral output can be controlled – are superior to incandescent and other legacy types of lights.
The summary of an article entitled “Light-Emitting Diodes in Architecture” published last year by in Wiley-Blackwell went into detail about the ramifications of LED’s ability to emit at very specific frequencies:
In greenhouses, such unique properties can be leveraged for precise control of flowering and product quality for the floriculture industry, for energy-efficient propagation of ornamental and vegetable transplants, and for supplemental lighting of high-wire greenhouse vegetable crops for all-year production. In a sole-source lighting mode, LEDs can also be used for transplant production, as well as for production of rapid-turning vegetable and small fruit crops.
The industry is beginning to actively leverage the advantages of LED for horticulture. Late last year Navigant Research said that the horticulture LED market has existed for a decade but is “now beginning to pick up steam” due to technical and quality advances. LEDs, according to the firm, could represent more than half of the horticultural light market next year.
The report says that the ability to focus on the most useful spectrums of light can increase yields by as much as 30 percent. There are less dramatic advantages that flow from the better known qualities of LEDs: The low level of heat they generate enable LEDs to be placed closer to plants. Thus, HVAC requirements are reduced and the density of plants in a greenhouse increases.
This suggests that the use of LEDs is not as simple as changing out the current lighting for the new. An article at Greenhouse Grower points out that many variables, including the precise growing environment of the greenhouse, the type of plants being grown and the time of year determine how the LED is used. Each of these elements impacts the spectrum, intensity and duration of the lighting. For this reason, an individualized plan encompassing all these factors must be created. The overall impression from the story is that the full benefit of LEDs only will be realized if a flexible infrastructure in which LEDs can be easily repositioned and agilely controlled is created. The bottom line is that the transition of greenhouses to LED lighting must be done very carefully.
The key is to understand that in horticulture LEDs are more than simply a more efficient way to provide light. They represent a qualitative as well as quantitative improvement – and are a linchpin to fundamental sector growth. “[T]hey aren’t just displacing old technologies, they are also helping enable an entire new industry of urban farming,” said Chuck DeMilo, Transcend Lighting’s Vice President of Sales and Marketing. “The transition in horticulture has been a little slower than in general lighting as some early LED products came to market prematurely and left a negative first impression. As LED technology continued to improve, the value proposition has become too compelling to ignore, and the horticulture market is now poised for mass adoption.”
Research is ongoing – and significant real world products and projects are being announced as well. For instance, last week Colorado State University in Fort Collins said it is partnering with Philips Lighting to outfit the new CSU Horticulture Center with LEDs.
The BizWest story said that the project is an outgrowth of the building of a new stadium, which required the relocation of greenhouses to the CSU Horticulture Center. That facility is schedule to be completed early this year. The move was seen as an opportunity for an industrial/academic partnership on LEDs with Philips.
Last week, Transcend announced the T5 high-output direct replacement lamp. The lamp, the company said, is aimed at the horticultural segment. The release says that that 30W lamp produces the same amount of light as a 54W T5 fluorescent, but reduces energy consumption by 45 percent. The emission spectra of the T5 matches the absorption spectra of plant and vegetative growth stages, which increases crop yield, the release said.
In November 2015, Illumintex introduced the PowerHarvest W. The aim of the light, according to the press release, is to cast a wider light in greenhouses. Since the characteristics of LEDs allow them to be mounted closer to plants, there is a need for a broader, widespread beam option. The PowerHarvest W is aimed at meeting this need.