08 Sep 4 Ways LEDs Enhance Environmental Control
A major benefit of implementing LED systems in a greenhouse is the reduction in overall operating costs in the form of energy efficiency, rebates, labor costs and enhanced control of the environment. Altogether, they represent a superior value proposition for greenhouse growers who are looking to retrofit their facilities. The ability to manipulate and, ultimately, control the environment through lighting technology is most critical to production—and often difficult to get right.
A solid understanding of how LED lights can improve environmental control is essential before, during, and after a retrofit. Here are four ways in which LEDs enhance environmental control for improved crop quality and yield.
1. Vapor pressure deficit (VPD) management becomes possible
HPS lights produce a significant amount of heat. When turned off, however, the resulting changes in the environment can leave crops more vulnerable to condensation and pathogens as they cool faster than other surfaces. This poses obvious and avoidable risks.
Under LEDs, the environment is less affected by heat produced from lighting, relying instead on the more precise HVACD system designed exactly for the management of maintaining set points in temperature and humidity.
This enhanced stability from LEDs ultimately translates to less condensation on plants, reduced water use and less dehumidification venting.
2. Achieving the perfect temperature with LEDs
The ambient temperature in a greenhouse plays a major role in the physiological functions and pollen development of certain crops such as cucumbers and tomatoes. With HPS systems, it is far more costly and difficult to maintain adequate heat levels, leading to fluctuations that stress plants.
Trials conducted by Wageningen University & Research, Fluence, and Vortus Greenhouse Consultants found that increasing the ambient temperature by 1°C for tomato cultivars actually increases crop production while lowering overall energy costs.
As a general rule, the optimal temperature for a greenhouse ranges between 26.6°C and 29.4°C. However, in an LED greenhouse, this optimal temperature setpoint is 1.0 to 1.5°C higher than a greenhouse with HPS lighting.
It is also worth noting that because LEDs emit less heat in the form of infrared radiation, LED systems provide greater opportunities to use supplemental lighting at times that wouldn’t be possible with HPS without risking plant health. While HPS lamps may perform two different tasks–both lighting and heating, they accomplish neither task particularly well and represent a far greater danger to plants should they fail. Ultimately, maintaining optimal temperatures should be the responsibility of the HVACD system.
An LED retrofit may require the addition of a heating system, but growers will often see reduced heating loads overall and, more importantly, favor their increased control of their environments.
3. LEDs stabilize CO2 by avoiding venting
As PPFD increases, maintaining supplemental CO2 levels is critical to maximizing photobiological responses and overall production. A concentration of 800 to 1,000 ppm is often the optimal range for most crops to promote flowering and improve yields.
However, growers who use HPS lights must vent their greenhouses either to dehumidify or cool their environments, creating wild fluctuations in temperature, humidity and CO2 levels.
LED systems decrease the need for venting, which allows for better climate control, CO2 preservation, increased photosynthesis, improved morphology and lower disease occurrence. For those dealing with light pollution regulations and/or using ceiling curtains, LEDs provide the added benefit of lowering the risk of overheating or causing fires, which can translate to reduced insurance premiums.
4. Higher PPFD levels and greater yields
HPS lights in traditional greenhouses supplemented crops upwards of 200 to 250 micromoles (µmol/m2/s). However, researchers studying the effects of LEDs are increasingly noting higher saturation points of many crops, creating new pathways to improve profitability for growers. An LED retrofit facilitates higher PPFD and improved production and growth.
Studies show that increasing PPFD also increases crop weight until the saturation point. In many cases, a 1% rise in PPFD has translated to a 1% increase in yield.
Today, cultivators are tapping into these findings and pushing PPFD levels as high as 300 micromoles (µmol/m2/s). When a facility replaces an HPS system with an LED system of similar wattage, supplementation capacity nearly doubles, assuming efficacies of 1.8 µmol/J for HPS and 3.5 µmol/J for LEDs.
Fluence experts are here to help
Understanding the benefits of LED systems on crop quality and yield is simple. Identifying and deploying the cultivation strategy that is best for your greenhouse is more challenging. That’s where Fluence excels.
If you’re looking to change the lighting system in your greenhouse to enhance your environmental control capabilities, contact us so we can learn more about your current system and provide a recommendation customized to meet your goals.