Plant Care
- • Climate Control & VPD16
- • Disease & Pest Management14
- • Nutrient Solutions & EC34
- • Plant Health Monitoring7
CO2 Enrichment & HVAC Engine
The Pro-level enrichment and safety blueprint for a sealed grow room. Volume, current and target CO2 in — the engine returns the exact kilograms of gas to inject with the leak rate baked in, the regulator run time, the per-day cost at your source price, a C3/C4-informed growth-boost curve gated by PPFD, the VPD and leaf-temperature interaction, and an OSHA-graded safety status with a 5000 ppm lockout.
Canopy CO2
live
canopy co2
1000
Ambient CO2
400
Injected CO2
600
Dashed arc — the share of the canopy total that injection delivers over ambient. Net holds in the centre.
Inputs
10 parameters · live recalculation on every change
M³
10m³
100m³ default
1000m³
PPM
300ppm
400ppm default
2000ppm
PPM
400ppm
1200ppm default
2000ppm
Pro Settings — Lab Controls
µMOL/M²/S
100µmol/m²/s
600µmol/m²/s default
2000µmol/m²/s
°C
15°C
25°C default
35°C
%/H
0%/h
10%/h default
60%/h
PPM
1500ppm
5000ppm default
10000ppm
Advanced Settings — Deterministic Corrections
KG/H
0.1kg/h
5kg/h default
100kg/h
Insight band · live
From ambient to canopy CO2
The room’s baseline CO2, lifted by the injection load — the running total lands on the concentration the canopy read.
- Ambient CO2 400 400.00 ppm
- + Injected CO2 600 1,000.00 ppm
- Canopy CO2 1000 1,000.00 ppm
Cost / day: $0.52
Growth boost: 15.00 %
Running total after each term — the final net matches the headline reading in the result card, kept in sync live.
Deterministic model
10 inputs · 10 outputs
Runs 100% in your browser
This is a deterministic model: the same inputs always produce the same outputs, calculated entirely in your browser with nothing sent to any server. It is a planning aid — not a quote, not a dosing instruction, and not a yield forecast. Treat every line as a working estimate and validate it against your own prices and measurements.
It models one system: The Pro-level enrichment and safety blueprint for a sealed grow room. Volume, current and target CO2 in — the engine returns the exact kilograms of gas to inject with the leak rate baked in, the regulator run time, the per-day cost at your source price, a C3/C4-informed growth-boost curve gated by PPFD, the VPD and leaf-temperature interaction, and an OSHA-graded safety status with a 5000 ppm lockout.
What the CO2 Enrichment & HVAC Engine returns
The engine computes 10 outputs from your 10 inputs. The headline number is CO2 Needed (kg), alongside Injection Time, Cost per Day, Growth Boost. Every output updates live as you change a parameter.
What it does not do
Outputs depend on the inputs and assumptions shown here. Confirm relevant measurements and local conditions before acting.
STEP 01
Measure the sealed room volume in cubic metres and the current canopy CO2 with a calibrated sensor.
STEP 02
Set the target on the crop physiology: C3 plants (tomato, lettuce, cannabis) saturate 1200–1500 ppm, C4 plants (corn, millet) 800–1000 ppm.
STEP 03
Compute the gas mass with the leak baked in: kg = V × Δppm × 1.8 ÷ 1e6 × (1 + leak/100).
STEP 04
Size the delivery: injection time = kg ÷ regulator rate, then project price × (fill + daily leak make-up).
STEP 05
Check the climate interaction: the CO2 load inflates the VPD band and lifts the leaf-temperature offset above air.
STEP 06
Grade the safety: green ≤1500 ppm, yellow ≤2000, red above 2000, absolute LOCKOUT at 5000 ppm — ventilate, never occupy.
m_{CO_2} = V \times (T - C) \times \tfrac{1.8}{10^6} \times \left( 1 + \tfrac{L}{100} \right)
CO2 mass — void fill scaled by the leak rate, near 25°C, 1 atm
t_{inject} = \frac{m_{CO_2}}{\dot q}
Injection time — kilograms ÷ delivery rate, in hours
C_{day} = \left( m + m \cdot \tfrac{L}{100} \cdot H \right) \cdot p
Daily cost — fill plus leak make-up across the photoperiod, at source price per kg
B_{C3} = 30 \cdot \log_2\!\left( \tfrac{T}{400} \right) \quad (\leq 50\%: PPFD > 600, \: \leq 15\%: else)
C3 growth boost — log₂ response on the ppm ratio, capped by light intensity
\Delta T_{leaf} = \frac{T - 400}{1000} \times 0.5
Leaf temperature offset — CO2-driven stomatal closure lets the canopy run warmer (°C)
VPD' = VPD_{band} \times \left( 1 + \frac{T - 400}{2000} \times 0.1 \right)
VPD adjustment — light-based VPD band inflated by the CO2 load
m_{leak} = m \times \frac{L}{100} \times H
Sustained leak make-up — hourly fractional loss × photoperiod
\text{Safety: } T \leq 1500 \; \text{green} \; \vert \; T \leq 2000 \; \text{yellow} \; \vert \; T > 2000 \; \text{red} \; \vert \; T \geq 5000 \; \text{LOCKOUT}
OSHA-grade grading — 5000 ppm is the 8-hour exposure ceiling
Leak rate dominates the real bill: a sealed room loses ~5%/h, a grow tent ~20%/h. The engine always sizes the dose and the daily burn against your leak, not the ideal void.
C3 versus C4 is not a nicety — C4 concentrators already pump CO2 around Rubisco, so going past ~1000 ppm buys nothing; C3 crops are the ones that reward 1200–1500 ppm.
The boost curve is capped by light: below 600 µmol/m²/s the ceiling drops from 50% to 15%, because the photonic flux — not CO2 — is the limiting reactant.
Burner delivery costs ~$0.50 per kg-equivalent versus ~$2.00 from a tank, but a burner dumps latent heat and combustion water into the room, which the VPD arm counts.
CO2 above 2000 ppm is not advisable in occupied spaces, and 5000 ppm (OSHA 8-hour TWA) is an absolute lockout. Seal-and-vent schedules apply.
The cheapest ppm is the one you do not lose: at 20%/h leak the make-up spend can exceed the fill spend, so door sealing often beats a cheaper gas source.
- CO2 gas mass factor: 1.8 g per m³ per ppm near 25°C, 1 atm — kg = V × Δppm × 1.8 / 1e6 × (1 + leak).
- C3 photosynthesis saturates near 1200–1500 ppm and gains up to ~30–50% over 400 ppm at saturating light; C4 plants saturate earlier near 800–1000 ppm (log₂ scale on the ppm ratio).
- Environment bands (PPFD → CO2 / temp / VPD) from the enrichment registry: <600 → 400–600 ppm, 0.8–1.0 kPa; ≥1000 → 1200–1500 ppm, 1.4–1.6 kPa.
- OSHA / ACGIH 8-hour time-weighted exposure limit for CO2 is 5000 ppm; sustained >2000 ppm is not recommended for occupied enclosed rooms.
This model combines the earlier Co2-calculator, Co2-enrichment-high-ppfd-1200-ppm, Cfm-air-exchange models.
Q1: What is CO2 enrichment, and why does C3 versus C4 matter? ▾
CO2 enrichment raises the ambient concentration above the ~400 ppm baseline so Rubisco fixes carbon faster when light is saturating. It matters which pathway your crop runs: C3 plants (tomato, lettuce, cucumber, cannabis) have no internal pump, so saturating light plus 1200–1500 ppm lifts assimilation sharply. C4 plants pre-concentrate CO2 around Rubisco, so they already saturate near 800–1000 ppm and extra gas above that is wasted.
Q2: What CO2 band should each growth stage run? ▾
Clones and seedlings 400–800 ppm (low demand, high sensitivity to heat load), vegetative growth 800–1200 ppm, and flowering or fruiting crops 1000–1500 ppm under saturating light. The engine caps your entered target at the stage band and at the light ceiling — a 1200 ppm ask under a 500-PPFD fixture is corrected to what the photons can actually drive.
Q3: What happens when the leak rate is high? ▾
Leak multiplies both the real dose and the sustained burn. At 20%/h, the room bleeds its enrichment every few hours, so the make-up spend can exceed the initial fill. The engine applies the leak factor 1 + L/100 to the dose and adds L/100 × photoperiod as daily make-up — which is why tank life and monthly cost collapse on a leaky tent long before they do on a sealed room.
Q4: Which CO2 source is more efficient — tank or burner? ▾
On pure gas price, a burner wins: roughly $0.50 per kg-equivalent against ~$2.00 from a pressurized tank, because combustion of propane forges CO2 directly. But a burner also dumps latent heat and water vapor into the room, raising the cooling and dehumidification load — the very VPD and leaf-offset arms this tool prices. Compost and mushroom co-location are free but rarely hold above ~800 ppm.
Q5: What are the real safety limits for CO2? ▾
OSHA and ACGIH grade a 5000 ppm 8-hour time-weighted average as the ceiling for occupational exposure; sustained elevated CO2 above 2000 ppm is not recommended in enclosed rooms. The engine grades green (≤1500 ppm), yellow (1500–2000), red (above 2000 — never occupy a sealed room) and LOCKOUT at your safety limit, default 5000 ppm. A controller plus vent schedule is the working layer under this planning math.
Q6: How do I optimize the cost of enrichment? ▾
Attack the biggest term first: leak. Sealing the room to ~5%/h collapses the make-up burn, often worth more than switching gas sources. Then pick the source for the season — burner for months of continuous high-PPFD flowering, tank for short runs. Finally, stop at the C3 saturation ceiling; every ppm above the crop genus and stage band adds heat and cost, not yield, which is exactly what the growth-boost cap enforces.