According to previous research, most plants in your greenhouse will not survive past temperatures of over 30 degrees Celsius. This also applies during summer, clear skies and high day and night temperatures. Therefore, require that you can maintain a suitable cool temperature for the growth of your plants. We need to first understand that heat transfer in your greenhouse occurs mainly by conduction, convection, and radiation. Therefore the ways to cool your greenhouse include cutting down on the heat gains into your greenhouse and maximizing on how to lose heat to the atmosphere.
Increasing air flow into your greenhouse is a very essential element in cooling it. You can either ventilate your greenhouse naturally or artificially.
With the right greenhouse kit, you can ventilate your greenhouse naturally by creating vents on your roof. I recommend that the area of these vents be at least a fifth of the floor area. With this, your plants will receive the air they need for growth and photosynthesis. Side ventilation is also very helpful for greenhouses. This can be achieved by using vents and doors. Once you open the doors, you ought to place a net over it so that air and pollinators enter but unwanted dirt does not get in.You can install timers and sensors on your vents and doors. They sense temperature rises and open automatically to allow air in for cooling the greenhouse. In case some parts do not receive enough natural ventilation, artificial ventilation can be used. Fans can be placed at strategic positions of the greenhouse. It is however recommended that you maximize the natural ventilation and reduce and if possible eliminate artificial ventilation. This is because these fans have a significant electricity bill rises. Solar-powered fans can be used instead.
During summer the ambient temperatures in your greenhouse will be higher. A lot of water probably in a 3000-gallon tank will have a much lower temperature than this general temperature. This high thermal mass of the water in the tank plays a big role in reducing this temperature. The tank should have a frame made of a sheet of metal to enhance this heat exchange.
Shading plays a key role in reducing heat gain into your greenhouse. However, there needs to be a great balance between shading your greenhouse and blocking natural light from reaching your plants. Natural lighting is very important for these plants since major processes like photosynthesis take place only in the presence of light.
You can use shade paint on your roofing. It is key to use a paint that can be brushed off. It moves a great way in reducing the sun's strong solar energy. As the heat increases as the summer progresses, you can add more layers of the paint.
Netting your greenhouse is also a measure that reduces heat gain. Though not very effective in cutting off much heat gain, mesh and nets are quite cheap.
A more effective sun shading device is the use of blinds. External blinds are more effective than internal ones. I recommend that you use removable blinds that can be removed during the colder seasons. An external blind can capture heat before it gets to your greenhouse glass. However, you need to locate them strategically so that they do not hinder the air vents.A shade cloth can also be used. Its working mechanism is similar to that of the shade paint. Probably placed on the roof or on the greenhouse facade that receives the most solar gain, it is a very effective shading device that can lower temperatures by up to 10 degrees. However, you need to get a balance so that it does not block the light key for the growing plants.
Trees and other vegetation should be planted around the greenhouse. This is a cheap and natural way of cooling your greenhouse. The trees provide a cool environment that cools the greenhouse. Also, they are key to block solar heat gain into the greenhouse. However, you should ensure they do not block sunlight from reaching the greenhouse.
This simply means increasing the amount of moisture in the air inside your greenhouse. You can do this by constantly wetting the solid hard surfaces in the greenhouse; the paths. The inside higher temperature makes the water evaporate. As it evaporates, the amount of moisture in the air will increase therefore cooling the greenhouse. I recommend that you dampen these hard surfaces regularly, probably three times in a day.
Increasing the humidity in the greenhouse will not only cool it but also help you get rid of unwanted pests which cannot survive in high humidity conditions.
You ought to always ensure that your plants receive enough water from below. This will not only enhance their growth but also help in cooling the greenhouse.
When your plants absorb enough water from the roots, they can transpire properly. Transpiration cools the plants as they lose water to the environment. Should they not transpire, they will wilt.
Greenhouses are very important in ensuring there is enough food production even during the hot summers and cold winters. As we have seen above, very high temperatures during the summer if not regulated will lead to the death of these plants. However, measures we put to reduce temperatures during hot seasons mustn't negatively affect the need for warming them up during the cold season.
That is the reason, for example, shade paint should be removable. If not, then during the cold season, it would block the sun's solar heat gain which will be much needed during that time. Blinds should preferably be removable too so that they do not block the much required solar heat gain too during the cold season.
We also need to find a balance between reducing solar heat gain and allowing sunlight into the greenhouse. Light is important and plants would not survive without it.
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