Accurate calculation of the greenhouse heating system

Many questions have been raised regarding how much heat a greenhouse of size X requires or how many heaters are needed for a given greenhouse area. In this article, we intend to introduce a simple formula that allows you to calculate the required heat for your greenhouse yourself. First, you need to consider two sets of parameters:

• Inside the greenhouse parameters: which depend on your plant type and cultivation method.

• Outside the greenhouse parameters: which depend on the local climate conditions of the area where the greenhouse is built.

To calculate the heat requirement, values from both inside and outside the greenhouse are needed, as outlined below:

• Coverage cross-sectional area: The total cross-sectional area of the greenhouse cover from which heat loss occurs.

• OPT value: If the cultivated plant is important to you and you want an ideal temperature, the OPT value should be considered.

• Min value: If your goal is only to prevent your plants from freezing, the Min value should be used.

Accurate Calculation of Greenhouse Heating System Using OPT Temperature

With these parameter values, along with the minimum outside temperature, you can easily calculate the required heat by placing them into the following formula:

Heat requirement = (min outside – min inside / OPT) * coverage cross-sectional area

Now, let’s explain the calculation with a simple example:

Here, we assume the minimum outside temperature and the optimal growing temperature as -12°C and 20°C, respectively.

The OPT temperature is obtained from the difference between the inside OPT temperature and the minimum outside temperature, which in this example is 32°C.

The coverage cross-sectional area for a 1,000 m² greenhouse is considered 1,650 m².

• Minimum outside temperature = -12°C

• Optimal growing temperature = 20°C

• Coverage cross-sectional area = 1,650 m²

• OPT = 32

By substituting these values into the formula, we reach the final result:

220,000 = 4.2 * (32) * 1,650

Thus, the coverage cross-sectional area multiplied by the OPT temperature and the constant 4.2 gives 220,000 kcal. This is exactly the amount of heat needed for a 1,000 m² greenhouse. (Note: The 220,000 kcal value is for a 1,000 m² greenhouse, based on the minimum regional temperature, the greenhouse coverage cross-sectional area—assumed here as 1,650 m²—and other parameters. This number is not fixed for every 1,000 m² greenhouse and depends on the region, inside and outside parameters, and your greenhouse’s cross-sectional area. All values given in this article are hypothetical to better illustrate the calculation.)

If you wish, you can also calculate the required heat based on the Min temperature as described below.

Accurate Calculation of Greenhouse Heating System Using Min Temperature

Similar to the previous example, certain values are needed to calculate the heat requirement using the Min temperature. The parameters required are listed below:

• Minimum outside temperature, considered as -12°C

• Min temperature, obtained from the difference between the minimum inside and minimum outside temperature, here 22°C

• Coverage cross-sectional area, which is 1,650 m²

• Minimum outside temperature = -12°C

• Minimum inside temperature = 10°C

• Coverage cross-sectional area = 1,650 m²

• Min = 22

Substituting these values into the formula yields 150,000 kcal. This is the minimum heat required to prevent your crops from freezing:

150,000 = 4.2 * (22) * 1,650

As you can see, using this simple formula, we calculated the required heat for a 1,000 m² greenhouse. You can calculate the heat requirement for your greenhouse in the same way. (All values mentioned are hypothetical and for illustrative purposes. In reality, for each 1,000 m² greenhouse, this number is not fixed and depends on the region, inside and outside parameters, and the greenhouse’s coverage cross-sectional area.)

Two Points to Consider When Purchasing Heaters for a Greenhouse

1. If your greenhouse is 1,000 m² and the heat requirement calculated is 200,000 kcal, instead of using a single 200,000 kcal heater, you can use two 100,000 kcal heaters. The reason is that if a single 200,000 kcal device fails, the entire greenhouse heating system is disrupted. Using two 100,000 kcal heaters provides redundancy, so if one system fails, the second maintains greenhouse heating, increasing overall safety.

2. Manufacturers often report higher output than actual. Therefore, when purchasing a heater for your greenhouse, consider a slightly lower capacity than what the manufacturer specifies.

Gol Afrouz Greenhouse Construction Company, with many years of proven experience, is a leading manufacturer in the field of modern greenhouses, ready to serve clients across Iran. By leveraging up-to-date knowledge and a specialized team, we design and build various types of Iranian, Spanish, Dutch, and tunnel-style greenhouses with the highest quality, tailored to your needs.

Additionally, Gol Afrouz provides all efficient and modern greenhouse equipment. If you are in Karaj, Tehran, or any other city in Iran and are looking for a reliable partner to build your greenhouse, visit our website today to contact us and benefit from expert consultation from our specialists.