An air conditioner for greenhouse can help regulate the right temperature to keep the healthy growth of plants. But with so many options available in the market, it might be difficult to know which is the best to choose.

In this post, we'll walk you through selecting the right air conditioner for greenhouse, so you can keep your plants thriving.

Determine the Greenhouse Size

Determining the greenhouse size is the first step you should consider. It will help you choose an air conditioner for greenhouse which is powerful enough to cool the entire space. 

First, measure your greenhouse's length, width, and height with a tape or laser for accurate results. You can take these measurements in the unit of meters or feet, depending on your preference.

Then you can:

Calculate the volume of your greenhouse:

V = L × W × H

For example, the greenhouse’s length is 20 feet, the width is15 feet, and the height is 10 feet, the volume would be 3,000 cubic feet (20 × 15 × 10).

Calculate the surface area of your greenhouse:

Surface Area = 2 × (L × H) + 2 × (W × H) + (L × W)

The surface area includes all walls, the roof, and the floor. Calculating the surface area is to determine the heat amount entering or escaping from the greenhouse.

3）You can also use an online calculator to determine the square footage.

Account for the Number of Plants and Equipment

The number of plants and the equipment you have in the greenhouse can affect the cooling needed.

Account for the Number of Plants

During respiration, plants produce heat. As a rule of thumb, a mature cannabis can produce the heat of around 150-200 BTUs/hr. So, a higher plant density may produce more heat and require more cooling.

Make a note of the plants number in the greenhouse, multiply the heat load by the total number of plants to estimate the heat generated by your plants to account for the extra cooling requirement.

For example, there are total 50 cannabis plants, a cannabis produces 180 BTUs/hr, so your greenhouse may need more cooling 9000 BTUs (50 x 180).

Account for the Number of Equipment

The equipment in your greenhouse, such as lights, fans, pumps and so on, also produce heat. Check the wattage (W) of each piece of equipment and convert it to BTUs, multiply the wattage by 3.41.

For example, a 500W light generates about 1,705 BTUs of heat (500 × 3.41).

Add the BTUs from all equipment to get the total heat generated by your equipment.

Estimate Heat Gain from Sunlight

You can use Solar Heat Gain Coefficient (SHGC) for your glazing material. SHGC is the fraction of solar radiation admitted through a window, door, or skylight.

Multiply the greenhouse's surface area exposed to sunlight by the SHGC to get an estimate of the heat gain.

Consider Insulation and Glazing

The type of glazing and insulation of greenhouse can affect the cooling requirements. Also make a note of the materials used and their insulation properties, they can help determine the proper air conditioner for greenhouse.

Add up All the Heat Loads

Add the heat generated by plants, equipment, and sunlight to determine the total cooling load.

Apply a Safety Factor

It's always good to apply a safety factor to account for any unforeseeable situation, such as equipment overheating, overload, heat waves, technical failures, or other factors that may increase cooling demand. Typically, a safety factor ranging 10-20% is suggested.

Kindly note, these calculations are rough estimates and can vary based on different factors, you can consult an HVAC professional to assist you with calculating the most accurate cooling need, and recommending the suitable air conditioner for greenhouse for your specific situation.

Consider the Local Climate

If you live in a hot and humid environment, you'll need an air conditioner for greenhouse with a higher cooling capacity.

If you live in a cooler environment, you may only need an air conditioner for greenhouse with smaller cooling capacity.

Tips: If in colder climates, a heating system is necessary, it allows the growers to provide optimal plant growth conditions. Read the use of the heating system in the following.

Additionally, you live in an area with frequent power outages. In that case, you may consider an air conditioner with a backup generator or battery backup to ensure your plants stay calm during an outage.

Determine the Type of Air Conditioner for Greenhouse

Consider your greenhouse size and your budget when deciding on the type of air conditioner for greenhouse.

There are three types of air conditioners to choose: window units, portable units, and split systems.

• Window AC: easy to install and can be cost-effective for more miniature greenhouses.
• Portable AC: also easy to move around and can be a good option for larger conservatories.
• Split AC systems: more expensive but offer better temperature control and energy efficiency.

Here is a table of differences among the tree type air conditioner for greenhouse:

Window AC:

Installation: Window AC units are designed to be installed in a window or a hole in a wall. They are relatively easy to install but require a suitable opening for placement.

Cooling capacity: These units typically have a lower cooling capacity compared to portable or split systems, making them suitable for small to medium-sized greenhouses.

Cost: Window AC units are generally more affordable compared to split systems.

Energy efficiency: They are less energy-efficient than split systems but can be more efficient than portable units, depending on the model.

Noise: Window AC units tend to be noisier than split systems.

Portable AC:

Installation: Portable AC units are freestanding and do not require any permanent installation. They can be easily moved around and require only an electrical outlet and a nearby window for the exhaust hose.

Cooling capacity: They can have a wide range of cooling capacities, making them suitable for various greenhouse sizes.

Cost: Portable AC units are usually more expensive than window units but cheaper than split systems.

Energy efficiency: These units tend to be less energy-efficient compared to window or split systems.

Noise: Portable AC units can be noisier than split systems but are generally quieter than window units.

Split AC (Mini-split or ductless AC):

Installation: Split AC systems consist of two parts - an indoor air handling unit and an outdoor compressor/condenser. They require professional installation, as the indoor and outdoor components are connected via refrigerant lines.

Cooling capacity: Split systems offer a wide range of cooling capacities and can efficiently cool larger greenhouses.

Cost: These systems are more expensive upfront but can save on energy costs in the long run due to their higher efficiency.

Energy efficiency: Split AC systems are known for their energy efficiency, making them an attractive option for long-term cost savings.

Noise: They are quieter than both window and portable units, as the noisy compressor/condenser is located outside.

Tips：High SEER Options

Look for units with high SEER (Seasonal Energy Efficiency Ratio) ratings.

It means how efficiently the team uses energy to cool your greenhouse. It will not only save cost but also reduce your greenhouse's carbon footprint. Additionally, consider using a programmable thermostat to control the temperature and reduce energy usage when the greenhouse is unused.

Complete Climate Control Consideration

We now know that, one standard method is using an air conditioner for greenhouse. It can help maintain a consistent temperature.

Other methods include: Natural Ventilation, Shading, and Evaporative cooling systems

They can help to prevent heat stress, disease, and other negative environmental factors. 

While the greenhouse protects from external factors, it's also essential to regulate the internal environment. This is where air conditioning comes in, with options for heating and cooling systems and humidification systems.

Air Conditioner for Greenhouse - Heating Systems

In colder climates during the winter, temperatures may be too low for optimal plant growth. Growers can regulate the inside temperature with heating systems to keep plants growing and thriving year-round, regardless of external weather conditions.

Besides, these system can maintain a suitable temperature range, they also can prevent frost damage and extend the growing season for plants.

In addition to regulating temperature, some greenhouse heating systems can also provide humidity control. By controlling temperature and humidity, greenhouse heating systems can help prevent plant stress, reduce disease risk, and promote healthy growth.

Air Conditioner for Greenhouse - Cooling Systems

If the temperature is too high in the greenhouse, it will cause plant stress, reduce growth rates, and even lead to plant death.

Therefore, a right cooling systems can help to prevent these issues and promote healthy plant growth.

Several greenhouse cooling systems are available, each system works differently, but the goal is to remove excess heat from the greenhouse space and replace it with cooler air.

• Evaporative cooling systems: use water to chill the air inside the greenhouse.
• Fan and pad systems: use fans to circulate air through wet pads to lower the temperature.
• Misting systems: spray a fine water mist into the air to reduce the temperature and humidity levels.

Air Conditioner for Greenhouse - Humidity Control

With proper heating and cooling systems, plants can avoid freezing temperatures in the winter or heat stress in the summer. And with proper humidity levels, it can reduce and avoid the spread of diseases among plants.

There are three ways to control the humidity in a greenhouse:

Using an air conditioner with a humidifier nozzle.

This air conditioner turns water into a fine mist and spreads it evenly inside the greenhouse with the help of a fan. Growers can control it remotely or set them to work automatically at specific times (Depending on automation level of the  greenhouse).

Choose an air conditioner with a built-in dehumidifier.

Add a separate dehumidifier.

Both method 2 & 3 could help remove excess moisture from the air in your greenhouse to maintain ideal humidity levels.

The Most Efficient Air Conditioner for Greenhouse

Air conditioners are essential components of a greenhouse air conditioning system. They work by circulating air through the greenhouse, removing excess heat and humidity, and distributing cool, fresh air throughout the space.

Greenhouse owners can maintain optimal plant growth conditions with the right air conditioner, even in the hottest and most humid climates. Whether growing vegetables, flowers, or other crops, an air conditioner for your greenhouse can help you achieve the best results.

Altaqua's air-handling products are not just for blowing cold air; they can also help maintain the right temperature and humidity levels in your greenhouse. With their lineup of air handlers, you can maximize your growing space while ensuring your plants are in the best environment for growth.

Altaqua offers a range of commercial air conditioners that can be customized to meet your greenhouse requirements, with units capable of handling 6 to 65 tons. Investing in a reliable and efficient air conditioning system can increase crop yields and cut costs in the long run.

So let Altaqua help you achieve happy and healthy plants for years. Altaqua offers greenhouse air conditioning systems to help growers produce superior crops in any climate. With a range of customizable options, our proposals meet the specific needs of your greenhouse and ensure optimal growing conditions. Contact us to know more about how we can assist you in achieving your ROI.