Controlled Environment Horticulture (CEH) Field Study: Adaptive Daylighting Controls

Adaptive daylighting controls were installed at a large cannabis greenhouse operation in central California to start exploring the potential for a deemed measure package for this technology.
The amount of light needed by a specific crop during specific phases of growth is specified as the target daily lighting integral (DLI). This is the unit of measure of a plant’s lighting needs, expressed as the number of photosynthetically active photons accumulated per square meter per day (mol/m²/d). Adaptive daylighting controls monitor the amount of natural light available using daylighting sensors and dim supplemental lighting as needed to ensure the target DLI is not exceeded.
Since recreational cannabis has only been recently legalized in California, this was the first study of its kind. Key findings were as follows:
1. For the site in this study, even a modest reduction in energy usage (9%) would provide an attractive return on investment. The equipment cost was $5,000 and the annual estimated utility bill savings was over $15,000 for a DLI of 50.
2. Because lighting controls affect the growing process, site training would be essential for any incentive package to be adopted by the market.
3. To have confidence in the technology, growers must be able to easily verify the equipment is properly configured and is dimming lights as intended.
4. While this study only analyzed potential cost savings from reduced energy use, growers could also realize financial benefits from shifting energy load away from times of peak energy costs, reducing demand charges, or receiving payments from participation in demand response programs.

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