Quick answer: A smart greenhouse climate control system is a climate computer connected to sensors and to every device that changes the climate: heating, vents, screens, fans, cooling, CO₂ dosing, lighting, irrigation and dehumidifiers. The computer compares measured conditions with the grower's targets for temperature, humidity (or VPD), CO₂ and light, and stages the devices in a set order. The value comes from coordination: one controller deciding, so the heating does not fight the vents and the dehumidifier does not fight the misting.
Quick answer
- Core: climate computer + canopy sensors + weather station + device outputs.
- Controls: temperature, humidity/VPD, CO₂, light, irrigation.
- Rule: one controller owns each decision; every device reports status back.
Greenhouse management system, environment control, HVAC: the terms
| Term | Usually means |
|---|---|
| Greenhouse climate control system / environmental control system | The climate computer, sensors and device outputs described here |
| Greenhouse management system | Climate control plus irrigation, crop records, labour and energy reporting in one software platform |
| Intelligent or smart control | Control that uses weather forecasts, models or optimisation instead of fixed setpoints only |
| Greenhouse HVAC | Heating, ventilation, cooling and dehumidification equipment; in closed and semi-closed houses, air-handling units with ducts |
| Agricultural climate control | The same principles applied to greenhouses, vertical farms, mushroom rooms and livestock buildings |
Components
| Component | Role | What to specify |
|---|---|---|
| Climate computer | Runs the control strategy, stages devices, logs data, raises alarms | Number of zones, inputs/outputs, communication protocols, remote access |
| Canopy sensor boxes | Air temperature, RH, sometimes CO₂ and leaf temperature at crop height | Aspirated shields, one or more per zone |
| Weather station | Outdoor temperature, humidity, radiation, wind, rain | Mounted clear of the house; used for vent and screen decisions |
| Heating | Pipe heating, hot-air heaters, heat pumps | Staging, valve control, temperature feedback |
| Vents and fans | Natural vents, exhaust fans, HAF fans | Positions, wind and rain overrides |
| Screens | Energy and shade screens | Positions; gap control for moisture release |
| Cooling | Pad, fog, shade | Interlocks with humidity limits |
| CO₂ | Dosing from tank or burner exhaust | Stop when vents open wide |
| Lighting | Supplementary LEDs or HPS | Light sums, switching by radiation |
| Irrigation | Timing by radiation or substrate sensors | Schedule linked to evening humidity |
| Dehumidifiers | Remove moisture when venting cannot | Start/stop and fault signals; capacity at house conditions |
How the climate computer coordinates humidity, temperature and CO₂
| Goal | Typical first action | Then | Conflict to manage |
|---|---|---|---|
| Lower temperature | Open vents | Shade, then cooling | Venting loses CO₂ |
| Raise temperature | Close vents, heat | Close energy screen | Humidity rises |
| Lower humidity | Air movement; heat and vent if outside air is drier | Dehumidifiers | Venting loses heat and CO₂ |
| Hold CO₂ | Keep vents closed | Dose | Humidity builds up |
The trade-off between holding heat and CO₂ and removing moisture is where dehumidifiers earn their place: they remove water with vents closed. Wageningen research has studied heating and dehumidification strategies in production greenhouses and optimal climate control with minimal energy (WUR, Heating and dehumidification in production greenhouses; WUR, Optimal control of greenhouse climate).
For the humidity staging sequence, deadbands and timers, see automated greenhouse humidity control.
Sensors: one reading is not the whole house
A Wageningen study with 100 wireless sensors in six commercial greenhouses found horizontal temperature and humidity differences that persisted even in five-day averages (WUR). So:
- use at least one sensor box per control zone;
- place it at canopy height, in an aspirated shield;
- add temporary loggers to find wet and cold zones;
- calibrate every season; see greenhouse humidity sensor placement.
Who decides what
| Decision | Owner |
|---|---|
| Crop targets (temperature, VPD, CO₂, light) by stage | Grower or crop advisor |
| Control strategy and staging order | Climate system designer, with the grower |
| Device safety and limits (compressor timers, drain alarms) | Device manufacturer |
| Sensor locations and calibration | Climate system installer, checked by the grower |
| Alarm response | Grower's operations team |
Write this down before buying equipment. Most problems in smart greenhouses come from devices with their own controllers acting independently, for example a dehumidifier on its built-in humidistat while the climate computer is venting.
Integrating dehumidifiers
- Let the climate computer start and stop dehumidifiers; disable or set wide the unit's own humidistat.
- Wire run, fault and drain-alarm signals back to the computer.
- Specify capacity at the night house condition, not only at 30 °C / 80 % RH.
- Plan condensate drainage and, where useful, reuse.
See our greenhouse dehumidifiers and how to choose a greenhouse dehumidifier.
Choosing a system: questions to ask suppliers
| Question | Why |
|---|---|
| How many zones, inputs and outputs, and can it grow? | Expansion is common |
| Which devices and protocols does it support (relays, 0–10 V, Modbus, BACnet)? | Dehumidifiers, heat pumps and lighting must connect |
| How does it control humidity: RH, VPD, dew point, leaf temperature? | Decides how well night humidity is handled |
| What happens if a sensor fails or the network drops? | Safe fallback protects the crop |
| How is data logged, exported and accessed remotely? | Needed for diagnosis and research |
| Who installs, commissions and supports it locally? | Most problems appear in the first season |
Commissioning in four steps
- Sensors: check each against a reference; confirm location and shielding.
- Devices: command each output and confirm it moves and reports status.
- Sequences: run each control sequence in real conditions (sunny day, humid night, cold night) and log the result.
- Failures: simulate a failed sensor, a tripped dehumidifier, a power cut; confirm alarms and safe fallback.
Keep the trends from commissioning as the baseline for later seasons. See greenhouse humidity control commissioning.
FAQ
Frequently asked questions
What is a smart greenhouse climate control system?
A climate computer connected to sensors and devices (heating, vents, screens, CO₂, lighting, irrigation, dehumidifiers) that holds the grower's targets automatically.
What sensors does a smart greenhouse need?
Canopy temperature and RH in each zone, outdoor weather, and often CO₂, light and substrate moisture.
Can dehumidifiers connect to a greenhouse climate computer?
Yes, typically by start/stop and status signals, so the computer stages them with vents and heating.
What is a greenhouse management system?
Software that combines climate control with irrigation, crop records and energy or labour reporting; the climate computer is its core.
What HVAC does a greenhouse need?
Most greenhouses use heating, natural ventilation, fans and shading; closed or semi-closed houses add cooling and dehumidification through air-handling units.
How do I stop devices fighting each other?
Give the climate computer control of every device and disable independent setpoints on the devices.
Sources
- Wageningen University & Research, Heating and dehumidification in production greenhouses; Optimal control of greenhouse climate using minimal energy; Using a wireless sensor network to determine climate heterogeneity.
- USDA-ARS, greenhouse climate control research publication.
