Vertical Farm CO2 Depletion Simulator

Rack Conditions

Ventilation rate 8 ACH

Plant density 70%

Light intensity (PPFD) 450 µmol/m²/s

CO₂ injection setpoint 1000 ppm

Tier CO₂ (bottom → top)

Live Readouts

Top-tier CO₂

— ppm

Bottom-tier CO₂

— ppm

Mean photosynthesis

—%

Sim. time elapsed

0 min

How it works

Photosynthetic CO₂ uptake follows a saturating (Michaelis–Menten-style) response to CO₂ concentration, scaled by a light-response factor:

Uptake_i = Umax · density · [L/(L+Ksat)] · [C_i/(C_i+Km)]

Each rack tier is treated as a well-mixed air volume fed by the tier below it (air is forced upward through the stack by the fans). CO₂ mass balance per tier:

dC_i/dt = (Q/V)·(C_(i-1) − C_i) − Uptake_i
C_(-1) = injection setpoint (fresh CO₂-enriched supply air)

Q is the volumetric airflow set by the ventilation slider (air changes per hour, ACH); Km ≈ 250 ppm is a typical C3-crop CO₂ half-saturation constant, and Ksat ≈ 250 µmol/m²/s sets the light half-saturation point.

Ventilation — more ACH pushes more fresh, CO₂-rich air up through the stack each minute, flattening the gradient between tiers.
Plant density — more leaf area per tier draws CO₂ down faster than it can be replenished, so upper tiers can starve even with a high injection setpoint.
Light intensity — brighter LEDs push plants toward their light-saturated photosynthetic rate, which raises CO₂ demand and steepens the depletion.
CO₂ injection setpoint — the concentration of the fresh air entering the bottom tier; real vertical farms enrich well above outdoor ambient (~420 ppm) toward 800–1200 ppm to boost yield.

Real-world relevance: sealed, densely-stacked grow rooms are well documented to develop a vertical CO₂ gradient — canopy-level depletion in the upper tiers — unless airflow is strong enough to keep pace with photosynthetic demand, which is exactly why commercial vertical farms size fans and CO₂ injection together rather than independently.

CO₂-rich (well supplied) CO₂-depleted (light-limited)

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