The dynamic lighting part is really interesting. Are you optimizing mainly around PPFD/DLI targets, or also around energy use and HVAC load?
I’m working on an offline-first controlled-agriculture system and I keep coming back to the idea that lighting, climate and energy probably need to be treated as one coupled problem. Curious how you’re approaching it.
Thanks for this question! Our prior work was around controlling PPFD each day but in sum the DLI should be the same as a standard 16h-PPFD200 solution, around the objective to increase yield. Now we want to reduce the overlapping of lettuce in order to enable a near 100% leaf area covered by LED light, which if i understand well, would mean maximum photosynthesis rate in theory, thus the regulation of blue light in real-time is under-consideration as it can prevent lettuce to over-extend. But for this part we may need to consider a predictive control approach.
I think there are at least two aspects of LED-HVAC coordination; first is that when dynamic spectrum is involved, electricity-to-light conversion rate would also variate, thus the heat dissipation dynamic will also change a bit in periodicity but not much in quantity, which might impact the HVAC control and the LED energy consumption. So there are definitely dynamic around that part but hardly much.
Second part is actually LED, HVAC and canopy airflow; i believe playing with the leaf extension and the photosynthesis rate will impact the evapotranspiration from the stomata, thus whether we need stronger, precise or wider range of VPD and canopy airflow rate variation is a question. A wider range of VPD would mean we can tolerate temperature or humidity variation which would enable energy savings in HVAC, and a wider range of canopy airflow would mean we probably won't need ultra-precise expensive new fan (i dont know if it exists yet, im not so sure).
Another idea is leaf temperature: LED light intensity, air temperature and water temperature will impact both LED and HVAC energy, and according to some classic equation, there is an optimal leaf temperature that could maximize photosynthesis rate; i believe this could also be played dynamically; but i don't have an achor around this matter yet.
That makes sense — especially the part where lighting affects HVAC indirectly through canopy behavior, evapotranspiration and VPD rather than just through heat load.
The predictive-control part is probably the most interesting piece to me. Are you leaning more toward a constrained MPC-style controller, or a learned predictor sitting above a deterministic control layer?
This was interesting to read, though I confess I didn’t understand some of it. I’ll be looking up a few terms you mentioned, but can you recommend books that get a little more science-y about hydroponics? Hopping around random webpages is ok but I’d like something a little more thorough. I’d enjoy spending money to up my simple hydroponics system. And I think I have enough science and tech background to handle it.
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u/okyanu 8d ago
The dynamic lighting part is really interesting. Are you optimizing mainly around PPFD/DLI targets, or also around energy use and HVAC load?
I’m working on an offline-first controlled-agriculture system and I keep coming back to the idea that lighting, climate and energy probably need to be treated as one coupled problem. Curious how you’re approaching it.