Abstract
A greenhouse creates a controlled environment around the crop, but the climate inside the structure is rarely completely uniform.
Temperature, relative humidity, radiation, ventilation, crop density and irrigation can create variations in environmental conditions across different areas of the same greenhouse.
Understanding this microclimate is important because plants respond to the environment surrounding their leaves and roots rather than simply to an average greenhouse measurement.
1. What Is Greenhouse Microclimate?
Microclimate refers to the environmental conditions within a specific location or small spatial region.
Inside a greenhouse, the climate measured near the entrance can differ from conditions near the crop canopy, roof or side walls.
A greenhouse may have one general climate, but individual plants experience a local microenvironment around their leaves, stems and root zone.
2. A Greenhouse Is Not Climatically Uniform
Air movement, solar radiation and crop transpiration continuously interact inside a greenhouse.
3. Key Environmental Variables
Temperature
Temperature affects photosynthesis, respiration, plant development, transpiration and pathogen activity.
Relative Humidity
Relative humidity describes how close the air is to saturation and influences plant water relations and disease development.
VPD
Vapour Pressure Deficit provides an indicator of atmospheric demand for water.
Air Movement
Ventilation and air movement influence temperature, humidity and the conditions around the crop canopy.
4. What Should Be Measured?
Environmental monitoring systems can combine several measurements to describe the crop environment.
| Variable | What It Tells Us | Agricultural Relevance |
|---|---|---|
| Temperature | Thermal condition of the air | Crop growth and physiological activity |
| Relative Humidity | Moisture status of the air | Transpiration and disease environment |
| VPD | Atmospheric water demand | Plant water relations and irrigation analysis |
| Air Movement | Movement of air through the crop | Heat and moisture distribution |
5. VPD as an Agricultural Indicator
Relative humidity alone does not completely describe atmospheric water demand. VPD combines temperature and humidity information into a measure that is more directly related to the drying potential of the atmosphere.
As temperature increases, the saturation vapour pressure increases. At the same time, a reduction in relative humidity increases the difference between saturation and actual vapour pressure.
This means that two greenhouse environments with the same relative humidity can still have different VPD values if their temperatures are different.
6. How the Crop Interacts With the Climate
The crop itself is an active component of the greenhouse environment.
Through transpiration, plants transfer water vapour into the surrounding air. Large crop canopies can therefore influence local humidity and air movement.
Radiation
Solar energy reaches the greenhouse crop.
Transpiration
Plants release water vapour through leaves.
Microclimate
Temperature and humidity change around the canopy.
Crop Response
Plant physiological responses change with the environment.
7. Why Average Climate Data Can Be Misleading
A single sensor may provide a useful representation of one location, but it cannot necessarily describe every point within a greenhouse.
Spatial Variation
Conditions near walls, entrances and roof areas can differ from conditions within the crop canopy.
Crop Density
Dense foliage can reduce air movement and create localized humidity differences.
Ventilation
Openings and fans can create changing patterns of air movement and temperature.
Irrigation
Irrigation and drainage influence water availability and the humidity environment around the crop.
8. How ClimaSense Approaches Environmental Monitoring
ClimaSense is designed to continuously collect environmental measurements and convert them into useful agricultural information.
Instead of treating temperature and humidity as isolated numbers, the platform can use them as inputs for agricultural indicators such as VPD and disease-risk analysis.
9. From Monitoring to Decision Support
The purpose of environmental monitoring is not simply to collect large amounts of data.
The greater value comes from interpreting that data in relation to crop management.
Climate measurements become more useful when they are connected to crop physiology, irrigation, disease risk and management decisions.
- Identify periods of high atmospheric demand.
- Observe prolonged high-humidity conditions.
- Monitor changes in greenhouse climate.
- Investigate unusual environmental patterns.
- Connect climate conditions with crop responses.
10. Future Research
Greenhouse microclimate research provides opportunities to connect environmental monitoring with more advanced agricultural models.
- Spatial mapping of greenhouse microclimate.
- Crop-canopy level environmental monitoring.
- VPD-based crop water-use analysis.
- Climate-based irrigation scheduling.
- Disease-risk prediction.
- Growth-stage-specific environmental analysis.
- Data-driven greenhouse optimization.
11. Conclusion
A greenhouse is a controlled production environment, but the climate experienced by plants can vary considerably within the structure.
Temperature, relative humidity, VPD and air movement interact continuously with the crop and greenhouse infrastructure.
Continuous monitoring provides the foundation for understanding these environmental dynamics and connecting them with practical crop-management decisions.
This forms an important part of the ClimaSense research direction: combining agricultural science, IoT sensing and data analytics to create better information for growers.