Smart greenhouse

In this review, I will talk about my own example of creating a smart greenhouse based on a greenhouse project.

In this smart greenhouse I decided not to use all indicators and devices, so I will list what is involved.

• A temperature sensor for the controller along with a cooler to cool it. This is a standard set up for any project.
• Temperature and humidity. I think it's obvious that these are the main indicators for the greenhouse. A remote wired sensor will be used for them. In principle, you can use two or three sensors in different parts of the greenhouse for more accurate readings.
• Soil temperature, also an important indicator. I will use it to make sure that the root system does not stop growing.
• As the main heating of the greenhouse I will use a gas or wood stove, as it is cheaper. This stove will form the basic heating. But, in order to achieve a stable temperature at night I will additionally use electric IR heaters of directional action. I liked this model. They will primarily warm the ground, plus create a heat curtain by heating the air.
• I will also be using the Soil Heater Temperature metric, but just not for its intended purpose. I will not measure the temperature of the heaters, but will place it near the plants, and call it "Plant Temperature". It will limit the work of heaters, so that warming the soil he did not damage the young seedlings.
• As for the climate, of course, I will need ventilation. It will remove and excess moisture and high temperature, and simply ventilate the greenhouse renewing the air mixture in it.
• In order not to put a powerful and expensive fan, I will also use the classic way of airing the greenhouse by opening the window. Of course, this will be done with a mechanical actuator. I have a separate video about how to make it. For its operation I will need to know the position of the window and control the actuator.
• I will also use a soil moisture sensor and a valve that will control irrigation.

The next step is to design the greenhouse. This is my first greenhouse, so a small size of three by six meters was chosen. As the main frame I took the eighty timber. For lintels, doors and windows fiftieth lath. And for tightening the frame used two-hundredth board. The structure will consist of six identical elements - posts with a slab and with rafters. In the first of them will be placed a doorway, and in the last - an airing window. The finished drawings will look as follows. The dimensions of the elements are chosen in such a way as to minimize the waste of lumber.

Well, after ordering and preparing the lumber, I proceeded with the assembly. This is what the rafter element looks like. As fasteners, I decided to use brackets, which are fixed with self-tapping screws.

As for the basis of the greenhouse, for this purpose a small strip foundation with external insulation was poured. On it the main posts are installed, treated with mastic at the point of contact with concrete.

This is how the assembled frame of the greenhouse will look like. These are six elements fastened with a board and lath.

As a roof, I decided to use cellular polycarbonate, which was laid on the insulation to eliminate gaps and gaps. It is strong enough, does not sag and perfectly copes with precipitation, including snow.

The greenhouse itself I decided to cover the sides with oilcloth. This is a fairly cheap and practical way. Of course, the main thing is to fix it well.

The greenhouse itself is ready. Let's see what it has inside.

First of all, these are the beds themselves. In my case, they are high beds. They warm up faster and it is more convenient to work with them. In total, it turned out to place four beds.

In addition, a small concrete pedestal was poured on which a cube barrel for water was placed. It is needed for two reasons. On the one hand for irrigation with warm water, and on the other hand, together with its pedestal it is a heat accumulator. Warming up during the day it will give heat at night.

Next to the barrel there will be a gas or possibly a wood stove. As I said, it will be stoked on days when there is a significant lack of heat so as not to waste expensive electricity.

This is what one heater looks like. It has a capacity of half a kilowatt. There will be a total of six heaters with a combined output of three kilowatts. They will be switched on through a contactor, which in turn will be controlled through a low-current relay.

Under the roof of the greenhouse there will be a duct with a built-in extractor. It will collect air in different parts of the greenhouse and blow it outside.

And of course, in addition to the duct, a drive for opening and closing the window will be installed on one of the gables of the greenhouse. With its help it will be possible to lower the temperature radically quickly in order to prevent overheating. In addition to the actuator itself, limit switches are installed on the frame of the window. They are necessary to determine the extreme position.

And now, of course, the control unit itself. This is how it looks from the outside. And this is how it looks without the top cover. Here is the controller board. It is the largest. To the right of it are the universal relay block boards. In the bottom right corner is the popular motor driver module, which will control the window actuator. To the right of the controller is the temperature and humidity sensor.

Two other sensors provide soil moisture and soil temperature measurements. Plus, as I mentioned earlier, another sensor is attached right next to the plant to measure the temperature near the plant.

We can start planting seedlings, and in the meantime I will show you the project settings and automatic modes of operation.

There will be only one specific setting, and that is when instead of "Soil heater temperature" I will measure "Plant temperature".

As for the automatic operation modes, there are several. That's not to say they have to be just that. I am showing my settings at this point in time. And you should realize that periodically I or my wife make some changes to them. So use them as an example only and create your own, more perfect ones!

Also, I strongly recommend you to read the tutorial video step number 6, which explains what the automatic modes are and explains in detail how they are set up. That way it will be much easier for you to understand what I'm going to tell you next.

So, the first mode is called "System". This is a service mode that will not be used independently, as you can see often its tasks can be found in other modes.

First of all, the conditions of controller cooling are set here. Temperature and time when the cooler is turned on.

Also basic notifications are configured here. Communication presence, controller temperature, unwanted air temperature, and a separate notification for critical air temperature. Last of all, there's humidity.

These notifications will be used for spring mode. For summer mode, when the greenhouse is already open, a different set of notifications will be used.

The next mode is called Spring. This is probably the most important mode for the greenhouse, because its main task is to ensure the successful growth of crops planted in early spring. Let's look at the tasks for the devices.

I'll start with heating. The main condition for the growth of seedlings is to try to maintain a soil temperature of at least 18 degrees. That's why this target temperature is set here. But the most interesting thing is that instead of the temperature of the heater, we will control the temperature of the plant in parallel.

The minimum is set to the same 18 degrees. What does that mean? It means that even if the soil is still warm and the air starts to cool down, the heater will already start to turn on. In this way the sudden drop in temperature of the air, which usually cools down faster than the soil, is mitigated.

The maximum temperature is set for other reasons. It is necessary to limit the work of heaters, so that warming the ground to the desired temperature they did not damage the seedlings. Then the heaters will periodically pause and turn off.

Now let's look at Ventilation.

In a greenhouse, excessive humidity will be a more frequent occurrence. Because of the poor insulation of the walls and the temperature difference, moisture will condense on them. Therefore, fighting high humidity with an extractor hood does not make much sense as for a living space. The first thing to do is to ensure guaranteed air recirculation, so that it does not stagnate contributing to phytophthora and plants can breathe.

The ideal extractor hood should work constantly to ensure a gradual and even air circulation. Alas, the reality is that ventilation will carry away heat along with the air. When overheating, this is of course a plus, but in early spring, it is a big disadvantage. Consequently, in cold times ventilation in the greenhouse will be a compromise between useful gas exchange with the removal of excess moisture and unwanted release of expensive and valuable heat.

Combining all of these tasks at the same time will not be as easy as it may seem at first. I have come to the decision that the removal of excess moisture from the greenhouse should be done by warming it up as much as possible. And the ventilation should work as long as possible, but long enough not to lower the temperature below a certain level.

In the end, I came up with this list of tasks:

First task. One-sixth of the capacity. Why one-sixth? Because according to this assignment, the ventilation will run for no more than ten minutes per hour, which is one sixth.

Note that here and below we ignore humidity. We only look at temperature. If the temperature is more than 13 degrees, then turn on the ventilation for five minutes every half hour. At the same time, if during these five minutes the temperature drops below 12 degrees, it is critically low and then we do without ventilation at all.

Also, it is interesting that I do not limit the working time of the hood here. Why this is so - will be clear a little later. And on the schedule. As you can see, I have forcibly excluded night ventilation, when heat should be protected especially.

Second task. One third of the power. It'll run the hood for another ten minutes an hour. So, added together with the first one, it will be two-sixths or one-third of one hour.

For this task, I've already raised the criteria for turning the ventilation on and off by temperature. This ventilation will turn on, or rather will be able to continue working after the first task, but only if the temperature in the greenhouse is high enough.

In addition, I have narrowed the time interval a bit so that the greenhouse warms up faster in the morning and loses heat slower in the evening.

The third task. Here I immediately add twenty minutes to one hour for ventilation. Summarized with the first two, it will be two-thirds of one hour. The criterion for the continuation of the ventilation will be an even higher temperature in it. Additionally, the time interval is also narrowed.

And finally, the fourth task. For continuous operation of the ventilation, an even higher temperature will be required. Similarly, the time interval is even narrower.

The last task is used to turn off the ventilation in any case. It has the lowest priority, i.e. it will only work when the first four tasks are not in effect. The reason why this task is necessary is to be absolutely sure that the ventilation will be switched off during the night period.

That's all we have to say about ventilation. And now it is time to tell about the work of the window for ventilation of the greenhouse.

As you can see there are two tasks. I will start with the main one, it is called "basic" and it works by default 24 hours a day.

Here is the first pair of dependencies. When the temperature is 18 degrees or less - the window position should be two percent. That is practically closed. And the second pair of dependencies at maximum. When the temperature is already more than twenty-six degrees, then the window should be open ninety-six percent.

We can also see that the minimum step to change the position of the window is set. Plus, there is also a maximum step to change the position of the window at one time. What is all this for? These settings prevent the actuator from jerking around needlessly and thus prematurely wearing out.

But that's not all. A very interesting parameter is the dependency curve. Here's our graph. It has two points according to the given conditions, it is the minimum point and the maximum point. The vertical scale is the percentage of window opening and the horizontal scale is the temperature.

The blue color on the graph shows a straight-line dependence, which is usually set by default. Why is it bad? And why did I decide to change it to a curve, which is shown in red color?

The point is that initially everything looks logical: the more the temperature rises, the proportionally more the window opens. However, in practice, you should take into account the factor that the temperature rise in a warm room can occur non-linearly, that is, very sharply.

Yes, theoretically, you can lower the temperature interval, so that the window opens in advance, as early as possible. But is it good? After all, in a good way, I need to keep the maximum allowable temperature in the warm room as long as possible. That is when the ground will warm up better and more, and then I will need to warm it up less in the evening or at night.

Simply put, timely opening and closing of the window of the greenhouse will give a significant saving on its heating, plus a natural bonus for the plants due to the longer warm period of the day.

That is why I have formed such a curve, which in the beginning of temperature rise, begins to gradually open the window, but the further you go, the more radical, in order to get ahead of the trend of temperature rise.

We've dealt with this task. But why do we need the second task? From its name and time of action, it follows that it will work in the evening. The basic task is necessary to open the window of the heater first of all in the morning and afternoon, but in the evening it should be closed in some other way.

Why? All for the same reason of economy and efficiency. In the morning and daytime we are allowed to open the greenhouse window early to remove the high humidity of the night and reduce the possibility of overheating, but in the evening we need to the opposite, to shift the compromise in the other direction and better warm the greenhouse, saving more heat. That's why I set a higher temperature interval in this task.

And what I have left for this mode is the watering device. There are no tasks here. Of course they can be set, but in my practice they are not needed yet. Because watering at the stage of seedling growth is done manually with feeding and careful inspection of the plant.

That's all. I remind you, I have dismantled the basic spring mode of the greenhouse. The main because the most important and responsible. It will determine how quickly the harvest can be obtained and at what price. However, of course, there are other modes.

The next will be summer. Let's see it by device.

Ventilation. Here one condition - on strong heat. In the summer mode, the window and door of the greenhouse are already ajar all the time. Therefore, the gas exchange of plants and humidity control on self-regulation. It remains only to remove excess temperature in case of overheating.

Heating. Will naturally be turned off in any case.

Watering, for the time being, is also switched off. Because it is not always needed yet.

And the window. As you can see it will be maximally open, with the only condition that the temperature should not be less than 18 degrees. In this case, the window actuator can close the window for a while at night. And even if the door remains open during this time, still due to the absence of a draft through the window, the smart greenhouse will be able to exclude accidental hypothermia.

Now the extended summer mode. You can see that it is completely identical to the previous summer mode. The same tasks for ventilation heating and window, but plus there are now their own tasks for watering.

Let's have a look at them. Watering consists of two tasks.

The first one provides a certain minimum of water delivery to the plants. It works independently of soil moisture and temperature. Switching on from morning to evening, at the beginning of every second hour with a ten minute work limit.

The second task, is basic watering. Its purpose will be to give the plants a good drenching to moisten the root system in depth and width as well as possible. It also works on a schedule. Strictly at ten o'clock in the morning and five o'clock in the evening. It is turned on for twenty minutes. Again, it does not depend on soil moisture or temperature.

Yes, I realize that it would be logical to make a task that would water plants based on humidity or temperature. But from my practice, measured watering has been more effective so far. Perhaps in the future I will add a condition for watering based on soil temperature when there is excessive overheating.

And the last mode is in the fall and winter. When the greenhouse is resting. Here everything is simple. Ventilation is off. Heating is off. Watering is off. The window is open.

This concludes the review of my smart greenhouse. I must say that this review was prepared for three years, through research and refinements. If we talk about the results, the smart greenhouse has proved to be excellent. First of all, it allowed us to get an excellent harvest two weeks earlier than a conventional greenhouse without automation, which showed worse results due to accidental overheating or overcooling.

In addition, the smart greenhouse saved our family a lot of time. It has added the ability to get away for extended periods of time during the summer with a sense of peace of mind thanks to remote monitoring.