The ventilation of the greenhouse is an essential point for a greenhouse as with heating, insulation, and watering. It is essential to ventilate a greenhouse in any season to ensure the smooth growth of your plants: ventilation helps to expel the moist and confined air that also promotes disease.
Natural ventilation allows hot air to escape while cold air enters through aeration ducts. For good ventilation, it will be necessary to ensure that the greenhouse has enough opening frames. Specialists consider that the opening sash surface must represent 20% of the floor area. The opening frames must be able to open at an angle of 50%. The side air intakes favor the movement of air: the fresh air is drawn in laterally, heats up inside the greenhouse and comes out through the opening frames.
For small greenhouses, opening the door can be important additional feature. When the greenhouse does not have sufficient natural ventilation, fans must be used to stir air at low speed to prevent drafts and the fans must be placed in height.
A greenhouse can be ventilated in many different ways, but some methods are more effective. The best methods of greenhouse ventilation allow the air to cool gently without disturbing the soft vegetation inside. One of the methods of ventilation is a roof or wall mounted vent that allows natural breezes to flow through the structure vents that open and close automatically are the best ways to ventilate a greenhouse. Indoor circulation fans can be an effective way to ventilate a greenhouse too.
A single vent mounted in the wall or roof is one of the cheapest greenhouse ventilation methods. This type of vent allows fresh air to flow through the structure of a door or open window. This method of ventilation allows air to circulate gradually through the chamber to remove heat and moisture. Large greenhouses usually require a series of vents strategically placed along the roof or walls. Louvered wall vents can be manually opened to provide extra ventilation when there is no breeze.
Automatic vents open and close when the temperature inside the greenhouse reaches a certain level. This method of greenhouse ventilation works without electricity, a fixed cylinder opens the vent automatically when a sufficient amount of heat builds. The vent closes when the air inside the greenhouse has cooled to electrically controlled automatic vents are controlled by a preset thermostat at a certain level of temperature or humidity.
Exhaust fans can also provide greenhouse ventilation by drawing outside air through the structure when a natural breeze is not present these fans are usually installed in front of the door to allow air to circulate completely through the structure. As the air of an exhaust fan blows outward, it does not disturb the delicate plants small greenhouses can usually be ventilated with only a single wall unit. Large structures may require one or more large exhaust fans mounted at each end with ventilation flaps in the side walls.
Exhaust fans can be controlled manually or automatically using a thermostat or solar powered exhaust fans can also be purchased to help reduce energy consumption. These units have a higher upfront cost but usually pay for themselves over time by reducing electricity expenses. Greenhouses use an indoor fan in combination with a fan to circulate the air and further reduce the temperature and humidity. This method of Greenhouse ventilation also helps to promote pollination between certain types of plants.
How to control the temperature
The structure must control a number of parameters. The temperature is one of them. Too high or too cold, the latter can slow down the development of plants grown indoors, or even endanger them. In the summer, the atmosphere in the greenhouse can quickly turn into furnace. The goal for the gardener is to maintain a temperature below 35 ° C.
The first thing you need to do is to open all the openings (door and windows) even to raise the sides of your tunnel greenhouse, if they are not buried. This helps circulate the air. It is therefore important to have at least two openings in a greenhouse.
Another option to lower temperatures is to limit the impact of the sun’s rays by installing a screen. One solution is to whiten the walls. A natural product used for a long time by the greenhouse users is the micronized chalk, which when mixed with water gives a whitewash with very great covering power. This type of whitewash is mainly used on glass walls, because it seems that there is a risk of alteration of the UV filters of some plastic supports. For plastic tunnel greenhouses or polycarbonate greenhouses, there are special shading paints that can achieve a shading rate between 45 and 80 degrees, depending on the dilution achieved.
Another solution may be the laying of shades. Some use old sheets, stretched inside the greenhouse, but it is possible to find, in specialist stores or on the internet, canvases designed specifically for greenhouses, acrylic (with aluminum strips) or polyethylene woven.
Some sit inside, stretched by wires, others surround the greenhouse outside. More efficient, the latter are, however, subject to climatic hazards and can deteriorate more quickly. The shading coefficient of these fabrics is approximately 60%, which makes it possible to lower the temperature of approximately 10 to 12 ° C. Bonus: some shading screens can also be used as a heat shield in the winter.
Most plants that are winterized are those that do not tolerate temperatures falling below 0 ° C. The goal this season is to protect crops from freezing. Depending on the model of the greenhouse and, in particular, the material used for its cover, it is more or less difficult to keep the cold outside and keep the heat inside; for example, the plastic covering a tunnel greenhouse is, undoubtedly, less insulating than the double-walled polycarbonate or the glass of the conventional rectangular greenhouse. Nevertheless, there are solutions to put in place (best ways to ventilate a greenhouse), which are adapted to each situation.