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The Future of Lighting for Greenhouses and Indoor Gardens

Posted August 2nd, 2018 by Eric Hopper in , ,

The 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 increasing 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 include some sort of high intensity discharge (HID) lighting. 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 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 components 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 reduces 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 interest. Ceramic metal halides have a full spectrum output and a color rendition index (CRI) rating around 90. The sun has a CRI of 100.

Light Emitting Diodes (LEDs)

The future of horticultural lighting cannot be discussed without mentioning light emitting diodes. Light emitting diodes (LEDs) have also come a long way since they were first introduced to the horticultural industry. Although the first generations of horticultural LEDs failed to meet the demands of indoor horticulturists, horticultural LED manufacturers didn’t stop working on more effective and more efficient LED lighting systems. The ability to customize the spectral output, a low heat signature, and the highest ratio of PAR per watt of energy consumed are all attributes of today’s LED horticultural lighting systems.

Chips on Board (COB) Light Emitting Diodes (LEDs)

One of the most recent developments in horticultural LEDs is the COB (chips on board) technology. COB LED systems have multiple light emitting diodes packed into a single module. The groups of LEDs in a COB system are easier to integrate into an effective horticultural light source. The most impressive feature of COB LEDs is their radiant efficiency. A typical HID (single ended) system has a radiant efficiency of around 30%. This means that roughly 70% of the electricity being used by the system is lost as heat and not converted into usable light. A COB LED has a radiant efficiency of 40-50%, which, relatively speaking makes them one of the most efficient artificial light sources for growing plants. All in all, COB LED lighting systems are the most efficient when it comes to converting electricity into usable light and are surely a technology that will help shape the future of horticultural lighting.

Fiber Optics

Fiber optics could potentially influence the future of indoor horticultural lighting more than any other technology. Fiber optic technology could enable indoor horticulturists to utilize the radiant energy of the sun, while maintaining the heightened control of an indoor garden. The potential of fiber optics is huge, but, at this time, the enormous cost is enough to stop this technology from becoming a staple in the indoor horticultural industry. Optical fibers are thin, flexible fibers made from glass or plastic. These optical fibers are commonly used for fiber optic communications where they permit transmission over longer distances and at higher bandwidths than traditional wire cables.

Optical fibers can also be used as a way to transmit light from one end of the fiber to the other. This application is how fiber optics could be relative to indoor horticulture. In fact, there are a few companies currently offering fiber optic solar collection lighting systems to consumers (for interior lighting in commercial applications). Although this technology is still years away from entering the indoor horticultural space, it is certainly a technology that may play a significant role in indoor gardens in the future. For a fiber optic solar collection system to be used for horticultural purposes, it needs three vital components to capture and redistribute the sunlight to the interior of a building. These three vital components are the collector, the fiber optic cables, and the cable terminal or light fitting.

The Collector

The collector of a fiber optic lighting system is the component that is placed directly in the sunlight (typically on the roof of the building). As its name suggests, the collector “collects” solar radiation and directs it into the fiber optic cables for redistribution. One very important component of the collector is the lens. In a way that is similar to a magnifying glass concentrating solar radiation, a lens on the collector concentrates solar radiation and aims it into the fiber optic cables. In order to maintain consistent light levels, the collector system needs to follow the movement of the sun. Collectors can be equipped with an internal clock mechanism, a photo-sensor, and a microprocessor which all work together to calculate the position of the sun and automatically adjust the angle of the collector for maximum light collection.

The Fiber Optic Cables

The fiber optic cables are the pathways for the radiant energy to travel into the building. The length of the cable, the wavelength of the light, and the quality of the cable itself all play significant roles in the loss of radiant energy during transmission. Fiber optic cables are extremely efficient and do not cause a large loss of radiant energy (light). However, to minimize light loss, it would be best to use the shortest length of the highest quality cables.

The Cable Terminal or Light Fitting

The cable terminal, or light fitting, is the component that distributes the light from within the fiber optic cable to the interior of the garden space. The light fitting(s) can consist of a series of different light diffusers or lenses which appear similar to conventional lighting fixtures. For indoor horticulture applications, a light fitting that most efficiently and evenly diffuses the sunlight would be most applicable. Depending on the size of the collector and the configuration of the fiber optic cables, multiple light fittings can be illuminated from a single collector.

Daily Light Integrals (DLI) for Greenhouses

Fiber optics could revolutionize indoor horticulture, but would do very little for greenhouse growers who already have access to the sun. However, many greenhouse growers rely on artificial light systems for supplemental light to extend the growing season and/or maximize their return on investment. Recent advancements in lighting automation allow greenhouse horticulturists to maximize the efficiency of their given supplemental lighting systems and provide the optimal amount of light for any given crop. All varieties of plants or crops have an ideal daily light integral, or DLI. The term “daily light integral” refers to the actual number of light particles (photons) received during a 24 hour period at a given location. By using a sophisticated lighting monitor and control system, greenhouse horticulturists can actually program a desired DLI for a crop. The monitor will trigger a lighting controller to turn on, off, or even dim the supplemental artificial lighting system as needed. These sophisticated greenhouse light monitor/controllers actually measure the intensity of the light and can, almost intuitively, control the artificial light system for the most effective combination of sunlight and artificial lighting.

The future of artificial lighting in horticulture is unknown. The sun is the pinnacle of radiant energy for plants and matching its power will always be a white whale for horticultural lighting system manufacturers. The use of solar radiation via fiber optics would change the way we view lighting for indoor gardening. When the cost of the collection and distribution systems for fiber optics becomes viable, fiber optics will become a revolutionary technology for indoor gardeners.

Until then, double ended HIDs, ceramic metal halides, and COB LEDs are the technologies that will shape the future of indoor growing. These efficient technologies will also shape the future of artificial lighting for greenhouses. Efficient artificial horticultural lighting systems teamed with sophisticated automation systems which adjust duration and intensity based on DLI measurements are currently the best choices for maintaining optimal lighting conditions within a greenhouse. Although the future is uncertain, there is no doubt that horticultural lighting will continue to evolve as horticultural lighting system manufacturers continue to chase the power of the sun.

Suggested Vendors

Growlite® 

Growlite® by Barron Lighting Group offers a full line of horticultural lighting products including state-of-the-art lamps, ballasts and fixtures engineered specifically for the indoor horticulture market. Growlite’s mission is simple; to provide the highest quality, safest products in the market and educate the indoor grow market with the lighting industry’s latest technologies. For more information call 800.533.3948 or visit Growlite.com.

P.L. Light Systems

P.L. Light Systems is a leading manufacturer of horticultural lighting systems that deliver unrivaled performance, quality and long-term dependability. P.L. Light Systems offers a complete range of innovative products in a variety of technologies, including LED, High Pressure Sodium (HPS), Metal Halide (MH), and Hybrid Systems. Their systems are engineered to deliver optimal lighting performance for plant growth and are built to the highest quality of production—combining Dutch craftsmanship with the most stringent North American regulatory standards. At P.L. Light Systems, everything they do revolves around delivering the very best supplemental grow lighting for each individual customer and application—from custom light plans and calculations to research and new product development. P.L. Light System’s underlying philosophy is based on an unwavering dedication to innovation that results in the delivery of optimal lighting performance and maximized yields for growers. In collaboration with their sister company in the Netherlands, Hortilux Schréder, they are constantly involved in research, new developments and improvements to our lighting solutions―ensuring they remain at the forefront of innovation and technology in the CEA lighting sector. P.L. Light Systems products are available throughout the Americas. For more information call 800.263.0213 or visit PLLight.com.

Spectrum King LED

Spectrum King LED, the pioneer of Full Spectrum LED Grow Lights (patent pending), specializes in designing, manufacturing and selling high-end LED grow lights for indoor and greenhouse applications targeting all variety of growing industries such as leafy greens, tomatoes, ornamental plants and more. As the leading innovator for LED grow lights, Spectrum King LED invests in all the latest technological developments along with actual live plant studies. Based in California, Spectrum King LED’s manufacturing facility and warehouse has automated robotic machinery, injection molding and assembly benches. R&D grow rooms are maintained for continuous scientific development and product innovation. Spectrum King LED holds powerful advantages over its competition and has an overall superior product in terms of design, performance and price. This places Spectrum King LED in a strong position to gain market share in a rapidly growing industry. For more information visit SpectrumKingLED.com.

Eric Hopper resides in Michigan’s beautiful Upper Peninsula where he enjoys gardening and pursuing sustainability. He is a Garden & Greenhouse senior editor and can be contacted at Ehop@GardenAndGreenhouse.net.

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