# Environmental Control Systems Deep dive into vertical farm environmental management. ## Overview Environmental control is the heart of vertical farming. Unlike outdoor agriculture, every parameter is controllable and optimizable. ``` ┌─────────────────────────────────────────────────────────────────┐ │ ENVIRONMENTAL CONTROL SYSTEM │ ├─────────────────────────────────────────────────────────────────┤ │ │ │ ┌────────────┐ ┌────────────┐ ┌────────────┐ │ │ │TEMPERATURE │ │ HUMIDITY │ │ CO2 │ │ │ │ Control │ │ Control │ │ Control │ │ │ │ │ │ │ │ │ │ │ │ HVAC │ │ Humidifier │ │ Injection │ │ │ │ Heat Pump │ │ Dehumid. │ │ Generator │ │ │ └─────┬──────┘ └─────┬──────┘ └─────┬──────┘ │ │ │ │ │ │ │ └─────────────────┼─────────────────┘ │ │ │ │ │ ┌─────▼─────┐ │ │ │ CENTRAL │ │ │ │ CONTROLLER│ │ │ └─────┬─────┘ │ │ │ │ │ ┌─────────────────┼─────────────────┐ │ │ │ │ │ │ │ ┌─────▼──────┐ ┌─────▼─────┐ ┌─────▼──────┐ │ │ │ LIGHTING │ │ WATER │ │ NUTRIENTS │ │ │ │ Control │ │ Control │ │ Control │ │ │ │ │ │ │ │ │ │ │ │ LEDs │ │ Irrigation │ │ Dosing │ │ │ │ Spectrum │ │ pH adjust │ │ EC monitor │ │ │ └────────────┘ └────────────┘ └────────────┘ │ │ │ └─────────────────────────────────────────────────────────────────┘ ``` ## Temperature Control ### Target Ranges by Crop Type | Crop Category | Day Temp (°C) | Night Temp (°C) | Differential | |---------------|---------------|-----------------|--------------| | Leafy Greens | 18-22 | 15-18 | 3-5°C | | Herbs | 20-25 | 18-22 | 2-4°C | | Fruiting | 22-28 | 18-22 | 4-6°C | | Microgreens | 18-21 | 16-19 | 2-3°C | ### Control Strategies ```typescript interface TemperatureControl { mode: 'manual' | 'scheduled' | 'adaptive' | 'ai_optimized'; // Setpoints daySetpoint: number; nightSetpoint: number; // Deadband (prevent oscillation) deadband: number; // ±1°C typical // Control outputs coolingStage: 0 | 1 | 2 | 3; // Multi-stage cooling heatingStage: 0 | 1 | 2 | 3; // Multi-stage heating } ``` ### HVAC Systems | System Type | Pros | Cons | Best For | |-------------|------|------|----------| | Split AC | Low cost | Limited capacity | Small rooms | | Mini-split | Zoned control | Moderate cost | Medium facilities | | Heat Pump | Efficient, heat recovery | Higher upfront | Production facilities | | Chilled Water | Scalable, precise | Complex, expensive | Large operations | ## Humidity Control ### Vapor Pressure Deficit (VPD) VPD is the key metric for plant transpiration: ``` VPD = Saturation Pressure - Actual Vapor Pressure Optimal VPD by Stage: - Seedling: 0.4-0.8 kPa (high humidity) - Vegetative: 0.8-1.2 kPa (moderate) - Flowering: 1.0-1.5 kPa (lower humidity) ``` ### VPD Calculation ```typescript function calculateVPD(tempC: number, humidityPercent: number): number { // Saturation vapor pressure (Tetens equation) const svp = 0.6108 * Math.exp((17.27 * tempC) / (tempC + 237.3)); // Actual vapor pressure const avp = svp * (humidityPercent / 100); // VPD in kPa return svp - avp; } ``` ### Humidification Methods | Method | Droplet Size | Coverage | Energy | Best For | |--------|-------------|----------|--------|----------| | Misting | 20-50 µm | Wide | Low | Propagation | | Ultrasonic | 1-5 µm | Targeted | Low | Small zones | | Fog | 5-20 µm | Wide | Medium | Large areas | | Evaporative | N/A | Wide | Low | Arid climates | ### Dehumidification ``` Sources of Humidity: ├── Plant transpiration: 95%+ of water uptake ├── Irrigation: Evaporation from growing media ├── Human activity: Breathing, sweating └── Fresh air: Outdoor humidity Removal Methods: ├── HVAC: Condenses on evaporator coil ├── Dedicated dehumidifier: Efficient for high loads ├── Desiccant: Continuous, no condensate └── Ventilation: If outdoor humidity lower ``` ## CO2 Enrichment ### Why Enrich? ``` Ambient CO2: ~420 ppm Optimal Growth: 800-1200 ppm Maximum Benefit: 1500 ppm Photosynthesis increases ~30-50% with enrichment ``` ### CO2 Sources | Source | Cost | Control | Safety | Best For | |--------|------|---------|--------|----------| | Tank (compressed) | Medium | Excellent | Safe | Small/medium | | Generator (propane) | Low | Good | Heat/humidity | Sealed rooms | | Fermentation | Very low | Poor | Safe | Hobby | | Air capture | High | Excellent | Safe | Large scale | ### Control Strategy ```typescript interface CO2Control { targetPpm: number; hysteresis: number; // ±50 ppm typical // Only enrich when lights on enrichDuringLightsOnly: boolean; // Integration with ventilation pauseDuringVentilation: boolean; // Safety limits maxPpm: 2000; // Worker safety alarmPpm: 1800; } ``` ## Lighting Systems ### Light Spectrum ``` Wavelength Ranges: ├── UV-A (315-400nm): Compact growth, secondary metabolites ├── Blue (400-500nm): Vegetative growth, compact structure ├── Green (500-565nm): Canopy penetration ├── Red (620-700nm): Photosynthesis, flowering └── Far-Red (700-800nm): Shade avoidance, flowering Optimal Ratios (general): - Vegetative: Blue 30%, Red 60%, Other 10% - Flowering: Blue 20%, Red 70%, Other 10% ``` ### LED Fixture Types | Type | Spectrum | Efficiency | Cost | Best For | |------|----------|------------|------|----------| | Full Spectrum | White + Red/Blue | Good | Low | General | | Red/Blue | Optimized peaks | High | Medium | Leafy greens | | Tunable | Adjustable | Good | High | Research, multi-crop | | Sunlight Replica | Full PAR + UV | Excellent | Very High | Premium produce | ### Light Metrics ``` PPFD (µmol/m²/s): Instantaneous light intensity DLI (mol/m²/day): Daily light integral = PPFD × hours × 3600 / 1,000,000 Targets by Crop: ├── Microgreens: DLI 8-12 ├── Lettuce: DLI 12-17 ├── Basil: DLI 15-20 ├── Tomatoes: DLI 22-30 └── Cannabis: DLI 40-65 ``` ## Nutrient Delivery ### Solution Management ```typescript interface NutrientSolution { // Primary monitoring ec: number; // Electrical Conductivity (mS/cm) ph: number; // Target 5.5-6.5 // Temperature tempC: number; // Target 18-22°C // Dissolved oxygen doPpm: number; // Target >6 ppm // Macro nutrients (ppm) nitrogen: number; // 150-250 phosphorus: number; // 30-60 potassium: number; // 150-300 calcium: number; // 150-250 magnesium: number; // 40-80 sulfur: number; // 50-100 } ``` ### Dosing Systems ``` ┌─────────────────────────────────────────────────────────────┐ │ DOSING SYSTEM │ ├─────────────────────────────────────────────────────────────┤ │ │ │ Stock Solutions │ │ ┌─────┐ ┌─────┐ ┌─────┐ ┌─────┐ ┌─────┐ ┌─────┐ │ │ │ A │ │ B │ │CalMag│ │pH Up│ │pH Dn│ │Sili │ │ │ └──┬──┘ └──┬──┘ └──┬──┘ └──┬──┘ └──┬──┘ └──┬──┘ │ │ │ │ │ │ │ │ │ │ ▼ ▼ ▼ ▼ ▼ ▼ │ │ ┌────────────────────────────────────────────────────┐ │ │ │ DOSING PUMPS │ │ │ │ Peristaltic pumps: Precise, low maintenance │ │ │ └────────────────────────────────────────────────────┘ │ │ │ │ │ ▼ │ │ ┌────────────────────────────────────────────────────┐ │ │ │ MIXING TANK │ │ │ │ - EC sensor │ │ │ │ - pH sensor │ │ │ │ - Temperature sensor │ │ │ │ - Level sensor │ │ │ └────────────────────────────────────────────────────┘ │ │ │ │ │ ▼ │ │ ┌────────────────────────────────────────────────────┐ │ │ │ GROWING ZONES │ │ │ └────────────────────────────────────────────────────┘ │ │ │ └─────────────────────────────────────────────────────────────┘ ``` ## Air Circulation ### Airflow Requirements ``` Purposes: ├── Temperature uniformity ├── Humidity distribution ├── CO2 distribution ├── Plant strengthening (thigmomorphogenesis) └── Disease prevention Velocity Targets: ├── At canopy: 0.3-0.5 m/s ├── Avoid dead spots ├── Avoid excessive wind stress ``` ### Fan Types | Fan Type | Use | Placement | |----------|-----|-----------| | Circulation | Air mixing | Throughout canopy | | Oscillating | Variable airflow | Above canopy | | Exhaust | Heat/humidity removal | High in room | | Intake | Fresh air, CO2 dilution | Low in room | ## Sensor Networks ### Sensor Placement ``` Zone Layout with Sensors: ┌─────────────────────────────────┐ │ [T/H] [T/H] │ [T/H] = Temp/Humidity │ ●───────────────● │ │ │ [CO2] │ │ [CO2] = CO2 sensor │ │ ● │ │ │ ┌───┴───────────────┴───┐ │ [PAR] = Light sensor │ │ [PAR] [PAR] │ │ │ │ ● ● │ Zone │ [EC] = EC sensor │ │ ▓▓▓▓▓▓▓▓▓▓▓▓▓▓ │ │ │ │ ▓▓ Plants ▓▓▓▓ │ │ [pH] = pH sensor │ │ ▓▓▓▓▓▓▓▓▓▓▓▓▓▓ │ │ │ │ [EC] [pH] │ │ │ │ ● ● (reservoir)│ │ │ └───────────────────────┘ │ │ │ └─────────────────────────────────┘ Recommended Density: - T/H: 1 per 20-50 m² - CO2: 1 per zone (at plant height) - PAR: 2-4 per zone (canopy level) - EC/pH: At each reservoir ``` ### Calibration Schedule | Sensor | Frequency | Method | |--------|-----------|--------| | Temperature | Monthly | Reference thermometer | | Humidity | Monthly | Saturated salt test | | CO2 | Quarterly | Cal gas (fresh air ref) | | PAR | Annually | Reference meter | | EC | Weekly | Cal solution | | pH | Weekly | pH 4.0, 7.0 buffers | ## Alert System ### Alert Thresholds ```typescript interface AlertThresholds { temperature: { warning: { low: targetMin - 2, high: targetMax + 2 }; critical: { low: targetMin - 5, high: targetMax + 5 }; }; humidity: { warning: { low: 50, high: 80 }; critical: { low: 40, high: 90 }; }; co2: { warning: { low: 600, high: 1600 }; critical: { high: 2000 }; // Safety }; ec: { warning: { low: targetEc - 0.3, high: targetEc + 0.3 }; critical: { low: targetEc - 0.5, high: targetEc + 0.5 }; }; ph: { warning: { low: 5.0, high: 7.0 }; critical: { low: 4.5, high: 7.5 }; }; } ``` ### Alert Escalation ``` Level 1: In-app notification ↓ (no response 5 min) Level 2: SMS/Push notification ↓ (no response 15 min) Level 3: Phone call ↓ (no response 30 min) Level 4: Emergency contact ``` ## Best Practices ### Daily Operations 1. **Check sensors** - Verify readings match reality 2. **Inspect plants** - Catch issues before sensors 3. **Review logs** - Look for trends 4. **Maintain equipment** - Filters, pumps, fans ### Preventive Maintenance | Equipment | Weekly | Monthly | Quarterly | |-----------|--------|---------|-----------| | Sensors | Visual check | Calibrate | Replace if needed | | Filters | Replace/clean | Deep clean | - | | Pumps | Check flow | Lubricate | Service | | HVAC | Check operation | Filter | Coil cleaning | | LEDs | Wipe | Check spectrum | Power audit |