GrowFlux Blog

Lighting controls: Three things to consider when selecting a horticultural lighting solution

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GrowFlux Wireless Access Point

GrowFlux Wireless Access Point

When planning a large scale Controlled Environment Agriculture (CEA) facility such as a hybrid lit greenhouse or indoor cultivation space, network resilience, network set up time, and installation cost are important factors to consider in selecting a horticultural lighting solution. Some lighting solutions on the market require zone controllers and data cables, which adds labor and cost to the installation process. Most wireless lighting control solutions require a multi step network setup process for each fixture, which adds up to a significant amount of time for facilities requiring hundreds or thousands of fixtures. 

For wireless control solutions, network resilience is an important factor to consider for large scale facilities. Unreliable lighting network connectivity can grind a large facility to a halt, sucking up time and resources to troubleshoot network issues all while the lighting solution is not performing as designed.

AetherMesh wireless module used in GrowFlux lighting and sensing products

AetherMesh wireless module used in GrowFlux lighting and sensing products

Only GrowFlux offers AetherMesh wireless controls on all of its products. AetherMesh was designed specifically for large scale CEA facilities and solves the issues discussed above:

Network resilience:

  • AetherMesh communicates on Sub 1-GHz frequencies and utilizes a high efficiency, high gain antenna, ensuring that wireless signals easily penetrate through dense buildings, multiple walls, concrete, and warehouses containing dense arrays of shelving.

  • Line of sight range of 1+ mile (1.6+ km) is possible between AetherMesh devices; indoor range through walls is typically upwards of 500ft (150+ m).

  • AetherMesh wireless mesh links self heal. If a device has trouble routing a message through one route, the mesh automatically finds another path through which to route messages. All network nodes maintain multiple network paths through which to route messages, choosing the most power and traffic efficient route in real time.

  • AetherMesh splits the 902-928 MHz band into 50 channels; the network automatically channel hops communication across these channels to avoid interference.

  • When we communicate lighting settings to a zone of fixtures, we send up to 90 days of scheduled control. This ensures that fixtures know exactly what they should be doing in the event of communication failure. Fixtures immediately get back to the correct scheduled control after any power failures.

Network setup time:

  • GrowFlux products incorporating AetherMesh wireless control set up rapidly out of the box - simply power on the device for the first time within 10 feet of your Access Point, and the device will securely join and remember the network within 30 seconds. AetherMesh network setup does not involve passwords, codes, IP address, or any other complicated network setup steps.

  • Connecting hundreds or thousands of fixtures happens as fast as the units are unpacked. Unpacking and initial power on occurs near an Access Point prior to hanging the fixture in the grow space.

  • Zone definition is entirely software based with our browser based interface - zones are not defined through network settings.

Installation cost:

  • One Access Point can support networks upwards of 1000 devices, significantly reducing cost

  • Zone definition is entirely software based, so hardware zone controllers are eliminated.

  • Every fixture on the network operates as a full power wireless mesh node (battery powered sensors perform limited extension of the mesh network to conserve battery life). This means repeaters and additional gateways are not required for large networks.

  • Since GrowFlux products are fully wireless, the installation labor and cost associated with data cables and controllers is eliminated.

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Coefficient of Utilization (CU) explained

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Coefficient of Utilization (CU) is a measure of how much light exiting the fixture will fall on a canopy area of a certain size; CU is an important factor to consider in designing an energy efficient Controlled Environment Agriculture (CEA) facility. CU is expressed as a ratio of the total light emitted by the fixture to the light that falls on an area of canopy of a defined size. It is important to note that the light that does not fall on the canopy directly under the fixture may either be wasted (to walls or floor), or may fall on canopy area adjacent to the fixture, depending on the design of the facility.

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Horticulture lighting standard ANSI/ASABE S640

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The American Society of Agricultural and Biological Engineers (ASABE) published the first of three standards for the horticulture lighting industry on August 8, 2017, bringing much needed codification to horticulture lighting technology. ANSI/ASABE Standard S640 titled "Quantities and Units of Electromagnetic Radiation for Plants (Photosynthetic Organisms)" establishes quantities and units used to describe light in relation to plants. Standards are important to the industry because they help everyone get on the same page with regard to the language used to describe the technology, the units of measure for lighting, metrics used to market products, and methods of bench-marking performance. 

The first of three standards, ANSI/ASABE S640, covers units of measure used to describe horticulture lighting. We took a look a the standard and summarized some key points:

1. PAR (photosynthetic active radiation) is a unit of measure of radiation relevant to plant growth, falls in the wavelength range of 400-700nm, and is expressed in two terms:

  • PPF - Photosynthetic Photon Flux - PAR emitted by a source, measured in units of micromoles

  • PPFD - Photosynthetic Photon Flux Density - PAR that falls on a unit of surface area

2. There are several ways to describe the wavelength portion of a PAR measure; these include Photosynthetic (400-700nm), UV (100-400nm), Far Red (700-800), and spectral (100-800nm). This results in terms such as Far Red Photon Flux Density, UV Photon Flux Density, or Spectral Photon Flux Density - in addition to Photosynthetic Photon Flux Density (PPFD). 

3. A measure may use two high level types of units to describe radiation: Radiate units (a quantity of energy) or Quantum units (a quantity of photons). This means Photosynthetic Photon Flux and Photosynthetic Radiant Flux both describe the same thing, however the first is expressed in micromoles (or µmol, a quantity of photons) and the latter is expressed in watts (W, a unit of energy). 

4. Far red light falls between 700 and 800nm

5. UV light is divided into three bands:

  • UVA - 315-400nm

  • UVB - 280-315nm

  • UVC - 100-280nm

6. There are two distinct ways to plot a PAR spectrum:

  • SPD, Spectral Power Distribution, a plot of PAR against wavelength, expressed in the units of radiant watts

  • SQD, Spectral Quantum Distribution, a plot of PAR against wavelength, expressed in the units of micromoles

7. Daily Light Interval is a measure of PPFD over a 24 hour period

Discussion

The standard discusses rationale behind several decisions, and notes that there is currently no accepted interpolation of bands across the PAR spectrum (as is the case with the UV spectrum). We have provided a brief summary of key components of the standard; we suggest readers purchase and read the full standard for a comprehensive overview of the units used to describe PAR. 

Whats next?

  • The Design Lights Consortium (DLC) will publish draft policy for energy efficiency in horticultural lighting in September 2018. This will create uniform requirements for energy rebates and incentives among utility providers

  • ASABE will publish the next horticulture lighting standard some time in 2018

Further reading:

 

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