5 Things To Check When Comparing Lighting Designs For LED Grow Lights
May 17, 2021
· When you compare different lighting designs, make sure to compare apples with apples.
· These are the 5 things to check when comparing lighting designs for LED grow lights.
Eindhoven, the Netherlands – As a grower, you invest in supplemental LED grow lights because they power the yield and quality of your crops. In fact, the rule of thumb is that 1% light output equals 1% crop yield. So, it is vital that your LED lighting investment delivers the full performance you paid for.
The performance is determined by the light intensity and light uniformity of the LED grow lights you use. If the installed light intensity is lower than what has been designed, there will be less yield. If the uniformity is inconsistent, individual plants will grow and develop at different rates and there will be uneven production in your greenhouse.
Before you start
When you compare different lighting designs, make sure to compare apples with apples. This means taking 3 things into account:
1. Verify the credibility of the performance claims that manufacturers make
2. Make sure that DIALux calculation software is used for the lighting design. This calculation software is independent and commonly used in the horticulture market.
3. Check which input parameters have been used for each lighting design. It is easy to tweak the input parameters and give the impression of a more positive light level and uniformity within the lighting design. So which parameters are crucial?
Most important input parameters to check
• Is the right product specified? Check if the exact product that you have selected for your project has been used in the lighting design; with the right light output (PPF in µmol/s) and spectrum (blue/red/white/far red/…)
• Are your specific design values used like the average light level at your crop (PPFD in µmol/m2/s) and the overall light uniformity?
• What are the standard settings? The height of the grow light and crop (free height), reflection factors, and size and position of the area that is used in the uniformity calculation have an impact on the average light level and overall uniformity.
#1 Check the free height
The first input parameter to check is the free height specifying the distance between the LED module and the head of the crop. The free height can seriously impact the overall uniformity value. In case of high-wire tomato crops, with a limited free height of 1.50 to 2.50m, realizing a good overall uniformity value can be a challenge. An optimistic free height or calculating uniformity on floor level as if there is no crop will positively impact the overall uniformity value.
The free height is calculated by measuring the eventual top of the crop and the mounting height of the LED grow light.
#2 Check the reflection factors
Another important parameter to check, are the reflection factors used in the lighting plan. A reflection factor indicates the amount of light that is reflected by walls and other objects in a space. DIALux calculation software has originally been designed for indoor spaces like offices, where you will get reflection off the walls, ceiling, and floors that impact the light level on your desk. To avoid being too optimistic about the outcome, the reflection values in DIALux are set at 0% for a greenhouse lighting design, because the glass in a greenhouse does not reflect the light from the grow lights.
#3 Check the area that has been used to make light intensity calculations.
The next thing to check is the defined calculation surface. The size of the calculation area and the position of the grow lights within that area will seriously impact the average amount of active photons that reaches the surface of the crop (PPFD value in µmol/m2/s). When comparing lighting design results from different manufacturers, make sure that the calculation surface shows an equal number of maximum (peaks) and minimum (dips) light intensity values. Only then you receive a realistic average PPFD value in the lighting design.
In the below example, you will see two positions of a calculation area within the same light plan, which will generate far better average light intensity values in the B situation, because the light intensity is calculated with an area that shows more grow light (peaks), and consequently less areas with the minimal amount of grow lights, which will not represent the reality after installation
Position of measurement grid defines the outcome of average light intensity
#4 Check the size of the calculation surface
Another important factor is the size of the calculation surface that will impact the overall uniformity value. When comparing lighting design results from different manufacturers, make sure the same calculation surface has been applied.
To represent a real-life situation, a calculation for the full compartment area should be made that includes the edges of the greenhouse. In case of a typical production area, a centred area is used. You may understand that a full compartment will generate lower uniformity levels, because of the lower light intensities at the edges. So, make sure you always compare either full compartments or smaller areas.
#5 Check the used uniformity
The final parameter to check is the uniformity being used. Uniformity can be expressed in different ways. When you run the DIALux lighting design software, it provides you with different types of uniformity. When comparing lighting design results from different manufacturers, make sure the same type of uniformity is applied. For a horticulture application, we prefer to express uniformity as the average light intensity divided by the maximum light intensity, which represents real-life situations best.
In Summary
When comparing lighting designs there are lots of tweaks that suppliers can possibly make to finetune their plan. In case you want to make a proper comparison, you have to take a few parameters into account.
- Is the specified product with the right spectrum and efficiency used in the calculations?
- Is the right light level for your crop used and the right overall light uniformity?
- Are the settings comparable:
o Is the free height correctly defined?
o Are the reflection factors set to 0%?
o Does the measurement grid have an even number of light and dark spots in it.
o Are you comparing full compartment or small centered area numbers?
o And is the defined uniformity similar in the lighting designs?
Read our other blog and learn how to evaluate the performance claims of an LED grow light.
Grow with the pros
You want to be sure to get a rapid return on your investment and have all aspects of your project carried out professionally. With Signify, your project is in experienced hands. Signify is the global leader in the lighting sector and has built up a substantial track record in more than 1000 projects in the horticultural lighting market since 1995. This includes over two decades of dedicated experience developing tailor-made, LED-based light recipes that help growers speed up growth, increase yield and improve the quality of plants. With cutting-edge LED innovations at our command, we can custom-build a science-based solution for you.
Pascal van Megen is an application engineer at Signify with a background in mechanical engineering. As an application engineer, Pascal ensures that growers are provided with high-end horticulture lighting designs. He is providing internal and external training to customers and partners in the application of the Philips LED Horticulture products and systems. He acts as a consultant to customers and engineers, to drive continuous improvement of Philips LED lighting solutions.
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For further information, please contact:
Global Marcom Manager Horticulture at Signify
Daniela Damoiseaux
Tel: +31 6 31 65 29 69
E-mail: daniela.damoiseaux@signify.com
About Signify
Signify (Euronext: LIGHT) is the world leader in lighting for professionals and consumers and lighting for the Internet of Things. Our Philips products, Interact connected lighting systems, and data-enabled services, deliver business value and transform life in homes, buildings, and public spaces. With 2020 sales of EUR 6.5 billion, we have approximately 37,000 employees and are present in over 70 countries. We unlock the extraordinary potential of light for brighter lives and a better world. We achieved carbon neutrality in 2020, have been in the Dow Jones Sustainability World Index since our IPO for four consecutive years, and were named Industry Leader in 2017, 2018, and 2019. News from Signify is located at the Newsroom, Twitter, LinkedIn, and Instagram. Information for investors can be found on the Investor Relations page.