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, and 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.
Dehumidification: Key to 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) and maintain stable humidity and temperature, optimizing plant growth.
Comparing climate control strategies
The study tested different methods of climate control and their impact on energy consumption, with data confirming 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, and create healthier conditions for plants, leading to higher yields and quality.
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