How Do Greenhouses Stay Cool In Summer?

In the sweltering heat of summer, greenhouses manage to create a haven for plants to thrive and flourish. But have you ever wondered how these structures maintain a cool and optimal environment for plant growth? With the scorching sun beating down on them, greenhouses employ innovative techniques to regulate temperature and prevent overheating. From shading systems to ventilation strategies, these marvels of horticulture have mastered the art of staying cool in the face of the summer heat. Curious to know more? Read on to unravel the secrets behind the remarkable cooling methods employed by greenhouses.

Shade and Ventilation

Shade Cloth:

One of the primary methods used in greenhouses to stay cool in the summer is the use of shade cloth. Shade cloth is a type of fabric that is specifically designed to filter and reduce the amount of sunlight that reaches the plants inside the greenhouse. It is typically made from a dense woven material that provides a certain level of shade, depending on the specific type used. Shade cloth can be easily installed and removed, allowing greenhouse operators to regulate the amount of shade provided. By reducing the intensity of sunlight, shade cloth helps to prevent overheating and sunburn damage to the plants.

Natural Ventilation:

Another important aspect of cooling greenhouses in the summer is natural ventilation. This involves creating openings or vents in the greenhouse structure, which allow for the exchange of air between the inside and outside. Natural ventilation relies on the principle of hot air rising and cool air sinking, creating a natural airflow that helps to remove excess heat from the greenhouse. These vents can be strategically placed and controlled to optimize the airflow and maintain a suitable temperature inside the greenhouse. Natural ventilation not only helps to regulate temperature but also allows for the removal of excess humidity, preventing the growth of mold and mildew.

Mechanical Ventilation:

In addition to natural ventilation, many modern greenhouses utilize mechanical ventilation systems to further enhance the cooling process. These systems typically consist of exhaust fans, intake fans, and circulation fans, which work together to maintain a steady airflow and control the temperature inside the greenhouse. Exhaust fans are responsible for removing hot air from the greenhouse, while intake fans bring in fresh cool air from the outside. Circulation fans help to distribute the cool air evenly throughout the entire greenhouse, preventing stagnant hotspots. Mechanical ventilation systems are often equipped with sensors and controllers that automatically adjust the fan speed and airflow based on the prevailing temperature and humidity conditions.

Evaporative Cooling

Evaporative Cooling Pads:

Evaporative cooling pads are an effective method of cooling that utilizes evaporative cooling principles to lower the temperature inside a greenhouse. These pads are made from a specially designed cellulose material that is porous and capable of absorbing and retaining water. The pads are installed at one end of the greenhouse, and water is continuously pumped onto them. As the water evaporates from the surface of the pads, it absorbs heat from the surrounding air, resulting in a cooling effect. The cooled air is then drawn into the greenhouse through exhaust fans, while the warm air is expelled. This process helps to reduce the temperature inside the greenhouse and maintain a more favorable growing environment.

Misting System:

Another popular method of evaporative cooling is the use of a misting system. Misting systems consist of tiny nozzles that release a fine mist of water into the greenhouse. As the mist evaporates, it absorbs heat from the surroundings and helps to cool down the air. Misting systems can be installed strategically throughout the greenhouse to ensure even distribution of the mist. By regularly misting the air, greenhouse operators can maintain a cooler temperature and provide a more comfortable environment for the plants.

Cooling Fans

Fan Placement:

Choosing the right placement for cooling fans is crucial for effective temperature control in a greenhouse. Fans should be strategically positioned to create a steady and uniform airflow. Placing fans near the vents or openings allows for the efficient removal of hot air and encourages the intake of fresh cool air. Additionally, fans can be strategically placed to prevent the formation of stagnant areas inside the greenhouse. By ensuring proper fan placement, greenhouse operators can achieve optimal cooling and airflow, resulting in a more consistent and suitable growing environment.

Fan Speed Control:

Controlling the speed of cooling fans is essential for maintaining a balanced airflow and temperature inside the greenhouse. High fan speeds can create excessive drafts and cause damage to delicate plants, while low speeds may not provide sufficient airflow for effective cooling. Many modern cooling fan systems come equipped with speed control options, allowing greenhouse operators to adjust the fan speed according to the specific requirements of the plants and prevailing weather conditions. By utilizing fan speed control, it becomes easier to achieve the ideal balance between cooling and plant protection.

Watering Techniques

Drip Irrigation:

Drip irrigation is a popular watering technique used in greenhouses to provide a consistent and controlled water supply to the plants. This method involves the use of small tubes with tiny holes or emitters that drip water directly to the plant’s root zone. Drip irrigation systems are designed to minimize water waste and reduce the risk of overwatering. By delivering water directly to the plants’ roots, drip irrigation helps to maintain soil moisture levels without unnecessarily wetting the entire greenhouse. This technique not only conserves water but also helps to regulate the temperature by preventing excessive humidity buildup in the greenhouse.

Misting System:

In addition to evaporative cooling, misting systems can also serve as a watering technique in greenhouses. By releasing a fine mist of water, these systems provide a gentle and uniform distribution of moisture to the plants and surrounding environment. Misting systems are particularly beneficial for plants that thrive in humid conditions or require constant moisture. The misting process can also contribute to cooling the air, as the evaporating water absorbs heat. However, it is important to ensure that misting is done correctly to avoid excessive humidity levels, which can lead to disease and fungal growth.

Fogging System:

Fogging systems are another water-based cooling and watering technique commonly used in greenhouses. These systems release a fog-like mist that quickly evaporates, creating a cool and humid environment. Fogging can help to lower temperatures inside the greenhouse and provide the necessary moisture levels for plants. By generating fine water droplets, fogging systems ensure better coverage and a more efficient delivery of water to the plants. However, proper control of the fogging system is essential, as excessive fogging can lead to excessively high humidity levels, which can negatively impact plant health.


Insulated Design:

Insulation plays a crucial role in maintaining a stable and suitable temperature inside the greenhouse. Greenhouses with insulated designs are better able to regulate heat transfer and prevent excessive temperature fluctuations. Insulated walls, roof panels, and flooring materials help to minimize heat loss during colder periods and heat gain during hotter periods. This helps to create a more stable and energy-efficient environment for the plants. Additionally, insulated designs also contribute to better soundproofing and increased resistance to external environmental factors.

Thermal Barriers:

Thermal barriers are another method used to improve insulation in greenhouses. These barriers are usually thin, reflective materials that are applied to surfaces to reduce the transfer of heat. By reflecting the sun’s rays away from the greenhouse, thermal barriers help to prevent excessive heat buildup. They can be applied to walls, roofs, and even windows. Thermal barriers are especially effective when combined with proper ventilation and shading techniques. The use of thermal barriers reduces the need for additional cooling methods, resulting in improved energy efficiency and reduced operating costs.

Roof and Wall Materials

Reflective Coating:

One way to reduce heat absorption in greenhouses is by applying reflective coatings to the roof and walls. Reflective coatings are typically white or light-colored paints that contain reflective pigments. These coatings help to reflect a significant amount of sunlight, reducing the amount of heat that penetrates the greenhouse. By reflecting the sun’s rays, these coatings can effectively reduce the interior temperature and lessen the need for excessive cooling methods. Reflective coatings are relatively easy to apply and can be reapplied as needed to maintain their effectiveness.

Shading Paint:

Shading paint is another useful tool for controlling solar radiation and reducing heat buildup in greenhouses. This type of paint is typically applied to the greenhouse’s external surfaces and is available in various shades and formulations. Shading paint works by absorbing or reflecting a portion of the sunlight, thus reducing its intensity inside the greenhouse. The chosen shade of paint will determine the amount of sunlight and heat that is blocked. By selecting the appropriate shading paint, greenhouse operators can effectively regulate the amount of heat gain and create a more comfortable environment for the plants.

Thermal Insulating Materials:

Choosing the right roofing and wall materials for a greenhouse is crucial for temperature control. Insulating materials such as double-layered polycarbonate or fiberglass can minimize heat transfer while still allowing desired amounts of light transmission. These materials provide a thermal barrier that prevents excessive heating during the day and heat loss at night. Opting for materials with good insulation properties contributes significantly to the overall energy efficiency of the greenhouse while creating a more stable and controlled environment for the plants.

Temperature Monitoring


Monitoring and maintaining proper temperature levels inside a greenhouse are crucial for plant health and growth. Thermometers are essential tools for temperature monitoring, allowing greenhouse operators to measure and track changes in real-time. Various types of thermometers are available, including digital, infrared, and mercury-filled thermometers. These devices can be placed strategically throughout the greenhouse to gather accurate temperature readings. By regularly monitoring the temperature, greenhouse operators can make timely adjustments to the cooling systems and implement appropriate measures to maintain an optimal growing environment.


Thermostats are advanced temperature control devices that automate the cooling process in greenhouses. These devices work by continuously measuring the temperature inside the greenhouse and activating or deactivating cooling systems based on predetermined temperature thresholds. By setting the desired temperature range, greenhouse operators can ensure that the cooling systems are activated whenever the temperature exceeds the set limit. Thermostats offer precise temperature control, enabling efficient and energy-saving cooling management. They are particularly useful in larger greenhouse operations where manual temperature monitoring may be challenging.

Cooling Strategies for Plants

Shade-Loving Plants:

One effective strategy for keeping plants cool in a greenhouse is selecting shade-loving plants. Some plant species naturally thrive in lower light intensity conditions and are better suited to dealing with high temperatures. By incorporating shade-loving plants into the greenhouse, greenhouse operators can create a microclimate that is cooler and more tolerable for these specific plant species. Shade-loving plants typically have adaptations to low light conditions, such as larger leaves for efficient photosynthesis or specialized structures that help them retain moisture. By catering to the specific needs of these plants, greenhouse operators can ensure their healthy growth and productivity.

Proper Plant Spacing:

Proper spacing of plants is another crucial factor for maintaining a cool and optimal growing environment in greenhouses. Overcrowding can lead to poor air circulation and stagnant hot air pockets, resulting in higher temperatures and increased humidity levels. Adequate plant spacing allows for better airflow and prevents excessive competition for resources. Providing sufficient space also allows plants to develop fully without shading each other. By following recommended plant spacing guidelines for different crop varieties, greenhouse operators can ensure that each plant receives the necessary amount of light and airflow, contributing to a cooler and healthier growing environment overall.

Watering Schedules:

Establishing appropriate watering schedules is essential for plant health and temperature regulation in greenhouses. Watering routines should be adjusted to suit the specific needs of each plant species and account for changing weather conditions. Consistency and moderation are key when it comes to watering. Underwatering can lead to stress and wilting, while overwatering can contribute to excessive humidity and disease. By carefully monitoring and adjusting the watering schedules, greenhouse operators can help maintain optimal soil moisture levels and prevent heat stress. Proper watering techniques, such as drip irrigation or misting systems, can further contribute to a cooler and well-hydrated greenhouse environment.

Sun Control

Shade Structures:

Shade structures are physical structures that are specifically designed to provide shade and reduce direct sunlight exposure in a greenhouse. These structures can be made of various materials, including shade cloth, polycarbonate panels, or even retractable screens. By strategically placing shade structures over certain areas of the greenhouse, greenhouse operators can create shaded spots and reduce the overall light intensity. Shade structures can be adjustable or removable, allowing for flexibility in managing the amount of shade provided. By combining shade structures with other cooling methods, greenhouse operators can create a more balanced and controlled growing environment.

Solar Reflective Coverings:

Solar reflective coverings are a passive cooling method that helps to deflect sunlight away from the greenhouse, reducing heat absorption. These coverings are usually composed of reflective materials, such as aluminum foil or special reflective films. They are applied to the greenhouse’s external surfaces, including the roof, walls, or windows. Solar reflective coverings effectively redirect a significant portion of the sun’s rays, preventing excessive heat buildup inside the greenhouse. By reducing heat absorption, these coverings play a vital role in maintaining cooler temperatures and minimizing the need for additional cooling systems.

Alternative Cooling Methods

Swamp Coolers:

Swamp coolers, also known as evaporative coolers, are another alternative cooling method used in greenhouses. These coolers work on the principle of evaporative cooling, similar to evaporative cooling pads. Swamp coolers use a fan that pulls air through moist pads, which then evaporates the water and cools down the air. The cooled air is then distributed throughout the greenhouse, reducing the overall temperature. Swamp coolers are particularly effective in arid or dry climates where moisture levels are low. They provide an energy-efficient cooling solution and can lower the temperature by a few degrees, making them a popular choice in some greenhouse settings.

Geothermal Cooling:

Geothermal cooling is a sustainable and energy-efficient cooling method that utilizes the stable underground temperatures to regulate the temperature inside a greenhouse. This method involves installing a geothermal heat exchange system, which circulates a fluid through buried pipes. The fluid absorbs the ground’s natural coolness and transfers it to the greenhouse, effectively cooling the air. Geothermal cooling systems can work in conjunction with other cooling methods, such as natural ventilation or evaporative cooling, to maintain a controlled temperature throughout the year. While geothermal cooling systems require initial investment, they offer long-term energy savings and sustainable cooling options for greenhouses.

In conclusion, greenhouses employ various strategies and methods to stay cool in the summer, providing an optimal growing environment for plants. Shade cloth, natural and mechanical ventilation, evaporative cooling, fans, proper watering techniques, insulation, roof and wall materials, temperature monitoring, cooling strategies for plants, sun control, and alternative cooling methods all play significant roles in maintaining suitable temperatures inside the greenhouse. By implementing a combination of these techniques, greenhouse operators can create a cooler and more productive environment, ensuring the success of their plant cultivation endeavors.

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About the Author: Jake Scott