New Study Highlights The Power of Dehumidification in Energy Efficiency
A recent study on a semi-closed greenhouse in Carquefou, France revealed a crucial factor affecting energy consumption: humidity control. While heating and ventilation are key components of climate management, uncontrolled humidity can drive up energy use and create poor growing conditions.
The study showed that implementing a dehumidification system could reduce energy consumption, stabilize plant growth, and improve overall efficiency.
About the Study
The study aimed to develop and validate a numerical model predicting energy use in greenhouses. Conducted over a full tomato cultivation season, the research analyzed heating demand, climate control systems, and the role of humidity in energy efficiency.
The greenhouse, a six-bay Venlo-type structure covering 1,037 m², was equipped with advanced climate control systems, including heating pipes, ventilation openings, and thermal screens.
The Link Between Humidity and Energy Use
Humidity plays a crucial role in greenhouse energy consumption. Excess moisture increases latent heat levels, making temperature regulation more difficult. In this study, it was observed that:
- Evapotranspiration from tomato plants naturally reduced indoor temperatures but maintained high humidity levels, forcing growers to use more ventilation and heating.
- Ventilation reduced humidity but also led to significant heat loss, increasing heating demand.
- Without a dehumidification system, the greenhouse needed 440 kWh/m² to maintain optimal conditions—an increase of nearly 42% compared to the baseline with proper thermal control.
The study found that when relying solely on ventilation for humidity control, relative humidity remained above 80% year-round. This resulted in inefficient energy use, forcing growers to use more heating to compensate for lost warmth.
| Climate Control Strategy | Energy Use (kWh/m²) | Impact on Humidity & Temperature | |
|---|---|---|---|
| No Humidity Control (Baseline) | 310 kWh/m² | High humidity (80% RH), higher heating demand | |
| Ventilation Only | 440 kWh/m² | Reduced humidity, but high heat loss and energy waste | |
| Dehumidification + Heat Recovery | 237 kWh/m² | Optimized humidity, lower energy use, stable climate |
Dehumidification: A Key to Energy Savings
By incorporating dehumidification instead of excessive ventilation, the greenhouse could maintain ideal humidity levels without unnecessary heat loss. The study showed that with an integrated dehumidification system, growers could:
- Reduce total energy consumption by up to 24% (from 310 kWh/m² to 237 kWh/m²).
- Maintain stable humidity and temperature, optimizing plant growth.
Reduce dependency on heating and ventilation, leading to lower operating costs.
Comparing Climate Control Strategies
The study tested different methods of climate control and their impact on energy consumption:
This data confirms that ventilation alone is not an efficient solution. By combining dehumidification with proper climate management, greenhouses can achieve a more energy-efficient and productive environment.
Why Growers Should Prioritize Dehumidification
The study underscores the importance of active humidity control in greenhouses. Without dehumidification, growers face higher energy costs, increased disease risk, and unstable climate conditions. By integrating a dehumidification system, greenhouse operators can:
- Reduce energy waste from excessive ventilation.
- Lower heating demand by maintaining a more stable climate.
- Create healthier conditions for plants, leading to higher yields and quality.
For modern greenhouse operations, dehumidification is not just an option—it’s a necessity for improving efficiency and reducing costs.
The study, titled “Heat Recovery Potential in a Semi-Closed Greenhouse for Tomato Cultivation” was conducted by Abdelouhab Labihi, Paul Byrne, Amina Meslem, Florence Collet and Sylvie Prétot, at Laboratoire Génie Civil et Génie Mécanique (LGCGM), University of Rennes.
