Food Autonomy recently collaborated with Plant Lighting as an independent research company to conduct a pilot study examining the effects of LEDFan technology on greenhouse climate and crop performance. The study, focusing on high-wire tomato cultivation, explored how integrating ventilation with LED lighting can influence airflow, temperature distribution, and plant responses.
LEDFan is a lighting fixture integrating LED modules with active air circulation. The system moves air through the fixture to redistribute heat and influence airflow within the crop canopy. The trial aimed to observe the localized effects of the technology and assess its influence on plant-climate interactions. By optimizing air circulation and heat distribution, LEDFan technology has the potential to improve both climate control and crop productivity in greenhouses. The findings provide insights into how growers can achieve a more efficient and controlled growing environment, contributing to sustainable horticulture practices.
Study design
The study took place in a high-wire tomato crop during full canopy development. LEDFan units alternated between active (fan on) and inactive (fan off) modes on a three-day cycle. Fixtures operated daily from midnight to 17:00, with the most measurable differences observed between 00:00 and 09:00. Measurements were taken at different canopy heights—top, middle, and bottom—and at two horizontal positions: directly beneath the fixture and between two fixtures.
Observed climate effects
Temperature and humidity sensors indicated that the strongest microclimate changes occurred directly under the LEDFan fixtures. With the fans active:
- Air temperature at the canopy level rose by up to 2.2°C.
- Relative humidity decreased.
- No consistent changes in leaf temperature were recorded.
These changes suggest an increase in transpiration activity without measurable stress to the leaf tissue. According to Martijn Wiekens of Plant Lighting, "The combination of elevated air temperature, decreased relative humidity, assumably more wind-speed and no changes in leaf temperature at canopy level with the fans of the LEDFan on, points to an increase in crop transpiration. Increased crop transpiration can lead to an increase in nutrient uptake."
Air movement and vertical climate gradient
The redistribution of warm air, typically accumulating near the roof, contributed to reducing the vertical temperature gradient within the greenhouse. Enhanced airflow was observed to shift heat downward toward the canopy, potentially offering growers a tool for modifying the spatial distribution of temperature.
Martijn notes: "One strategy to potentially alleviate the microclimate heterogeneity is the use of fan technology. Fans can alter the movement and distribution of air, enhancing air mixing and potentially improving the homogeneity of the greenhouse climate and the leaf and fruit temperature."
Transpiration and nutrient uptake
The combination of increased canopy temperature and decreased relative humidity created conditions favorable to higher transpiration rates. The data suggests plants were able to regulate their leaf temperature through evaporative cooling, and this physiological response may support more efficient nutrient uptake under LED lighting.
Heating demand implications
During LED operation periods, researchers recorded a decrease in heating pipe temperatures when LEDFan was active. This observation indicates potential for energy input reduction. The scale and duration of this effect remain areas for further study.
For more information:
Food Autonomy
[email protected] 
www.foodautonomy.org
Plant Lighting
www.plantlighting.com 