7 Top Ways to Cool A Greenhouse Without Electricity
You want a greenhouse. You know it will build up a lot of heat during the day. Even on sunny days in the middle of the winter. You want to put it by your garden in a remote corner of your lot. Or maybe, on some land that you own that is undeveloped. What do you do? Fortunately, there are multiple options for cooling your greenhouse even when you don’t have electricity. Let’s take a look at the options.
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This one is a no brainer. Just install a shade cloth over the top of your greenhouse. It has much the same effect as standing under a shade tree in the summer. The shaded area will be cooler. Shade cloths are available in a woven, knitted or reflective material. The woven material will ravel when cut and it is necessary to put tape on the edges. Knitted shade cloth has more give than the woven and does not require taping, although we prefer to do this as you can then put grommets in the tape. You can run a bungee or cord through the grommets to attach the cover to your greenhouse. There is also a reflective cloth available which is much more efficient. They result in lower greenhouse temperatures and a more consistent environment. Shade percentages run from 50% to 70% for greenhouse use, maybe lower for plants will low light requirements.
Chances are if you are purchasing a greenhouse kit, it will have roof vents. There are very few kits out there without roof vents, and if you are building your own greenhouse, this is a highly desirable feature. We all learned in high school that warm air rises. Have an opening such as the roof vent in the top of your greenhouse, and the hot air will exit. Manual roof vents are available, but the best way to take advantage of this feature is to have a solar powered opener on it. That way if you are not at the greenhouse every day, you will know that the vents are opening and closing at appropriate times. These solar powered openers are basically wax cylinders. They work on the principle of contraction and expansion. When they get warm they expand, pushing the vents open. When they get cool they contract, pulling the vents shut. These can be adjusted to a certain degree to open and shut at desired temperatures.
There are also roof vents available that will go directly into a polyfilm greenhouse without additional framing. They have the solar powered openers. These vents can be retrofitted onsite to fit in a polycarbonate greenhouse.
3) Side vents in conjunction with roof vents –
Greenhouse with side vent
If you place a side vent with a solar powered opener below your roof vents you will get even better ventilation in your greenhouse. We like to place these approximately 6″ from the bottom of the greenhouse. This will give you a chimney type effect drawing the air from the bottom to the top of the greenhouse. We also use the wax cylinders on these to keep things simple.
If you have a greenhouse with straight side walls you can install roll up curtains. Using these you can roll the greenhouse sides up during the hottest times of the year. These systems operate with a hand crank or can be automated. These come with a heavy duty 12 mil coated weave fabric. It is recommended to use a kneewall with these systems. That way your plants will have protection from the wind when the curtains are open. Also, if you are in a heavy snow area, this will keep the snow from laying up against your curtain.
These operate on the same principle as a wired ventilation package. But, they are powered by a solar panel. The exhaust fan goes up high in the backwall of the greenhouse. The intake shutter(s) go down low on the opposite wall. The exhaust fans are wired to a thermostat. The manual intake shutters will open to allow fresh air into the greenhouse. The exhaust fan will draw this air through the greenhouse, cooling the air. No electricity is required, you are creating your own power.
12 inch solar powered circulating fan for greenhouse
Circulation fans are essential to the healthy greenhouse. They will increase CO2 availability, an essential for plant growth. They help to reduce excessive moisture creating an environment which reduces disease and pests caused by humid environments. They also help strengthen the plant stems with the same motion as a mild breeze when the plants are grown outside. These are fans that run low and slow.
7) Misting Systems –
Misting systems may be used if you have water to your location. They will help to lower the heat in a greenhouse. These can be set up on a battery operated timer, so no electricity required. These cause a cooling effect by tiny water droplets evaporating.
In Conclusion
I have been fighting an uphill battle at times throughout the years. New greenhouse owners just do not understand the heat that will build up in a greenhouse during sunny days, even in the middle of winter. I have seen my ventilation package come on during a sunny 60 degree February day. And, I keep my thermostat set at 90 degrees. Quite a difference that you really would not expect unless you have experienced it. Proper ventilation is an essential item for your greenhouse. It will keep your plants healthy and happy. No more baked tomatoes on the vine. You will have to pick them and put them under the broiler in the kitchen for that! These options discussed above provide you with the opportunity to supply adequate ventilation to your greenhouse even when they are in an area with no power available. So, no more excuses. Get out there and build yourself a greenhouse today. I will also be discussing heating your greenhouse without electricity when the season dictates. Good Growing!
Are you building a homemade polyfim greenhouse, but are unsure about how to ventilate it? Here are a couple of solutions for you. You can see that this greenhouse has roll up sides, an option which is readily available, but can be costly. We have 2 options available that insert directly into your polyfilm covering without any additional framing. They use the channel base and wiggle wire to insert directly into the greenhouse covering. You simply cut the film and install these accessories directly into the film covering without any additional framing.
Intake Shutter with Solar Powered Opener
The first option is a solar powered greenhouse shutter. This has louvers and a wax cylinder powered opener. It will open when it is warm and close when it is cool automatically. They are available in 6 different sizes. If you would like to use this on another type of greenhouse such as polycarbonate, we can remove the base channel and you can insert this directly into a wood framed opening.
Solar Powered Roof Vent
The second way to do this is with a solar powered roof vent. This is a lightweight polycarbonate vent. It weighs less than 10 pounds, but you get all of the benefits of the durable polycarbonate covering. It also has the was cylinder powered opener that will automatically open and shut the vent as the temperature requires. To install this you simply cut the polyfilm and install it directly into the greenhouse covering.
A lot of people prefer to build their own greenhouses rather than purchase a kit. With these 2 ventilation options, there is no reason not to build your own polyfilm greenhouse.
This is an excellent article from our friends at Garden and Greenhouse magazine regarding the need for consistency in your greenhouse environment. In order to have the best, consistent growth it is important to have the best, consistent climate. Although I must say that I find this a little bit more on the advanced end of greenhouse growing. I do not suggest that someone jump in with every known greenhouse accessory when initially purchasing their greenhouse. I recommend getting a ventilation system, as it is an integral part of the building. You can retrofit them, but it is easier to install them when you are putting up your structure. A heater is also a good accessory to order with your greenhouse. As far as some of the other systems are involved, I suggest experimenting and finding out what you need rather than outlaying a bunch of money for accessories that your climate or plants may not need. Unless you are an experienced orchid grower, for example, you will know what humidity, etc your plants will need. Then it would be a wise decision to get your greenhouse set up with these systems at the beginning.
Consistency is the key to unlocking the maximum potential of an indoor garden or greenhouse. Plants thrive on consistency. Plants respond best to light energy, atmospheric conditions, and nutrients when they are kept as consistent as possible. Like people, plants burn sugars to provide energy for growth. In contrast to people, plants have the unique ability to create those sugars from sunlight. The creation and consumption of these sugars are actually part of a chemical equation. In other words, there are countless chemical reactions occurring at all times within and around the plant that contribute to healthy development.
When atmospheric conditions, lighting and nutrient levels are at optimal levels, the plant has everything it needs to make those chemical reactions happen without interruption. When the chemical reactions can occur without interruption, the plant’s growth rate is maximized. Maximizing the potential of a particular crop is the goal of just about every indoor horticulturist or greenhouse hobbyist. In order to maximize the potential of an indoor garden or hobby greenhouse, a horticulturist should closely monitor the consistency of the garden’s temperature, humidity, lighting and nutrient solution. Each of these factors has a significant effect on the chemical reactions that contribute to plant growth.
Greenhouse with Solar Powered Roof Vents and Side Vents
Of course the answer to this question is yes, you do need ventilation for your greenhouse. But what if your greenhouse is in a location with no electricity? There are several options which will alleviate this problem. The simplest thing to add is roof vents or side vents. A lot of the greenhouse kits will come with these either as standard equipment or as an option. If you are building your own greenhouse, you would just frame them out using the same material as your greenhouse and cover them with the same material as well. To simplify matters even more, I recommend using solar powered openers with these. This is an arm that is operated by a wax cylinder. It is a pretty basic piece of equipment. It functions on the principles of contraction and expansion. When it is warm the wax will expand and cause the arm to open. When it is cool the wax will contract and cause the arm to pull shut. There is no exact temperature setting on these, but there is a thumbscrew at the end which can be used to adjust the opening and closing temperatures. They are typically able to open between 65 and 75 degrees F, depending on the manufacturer. They will definitely simplify your life during the spring and fall months. No more getting up in the morning and opening them before you head out to work. Then, if you get home and forget to close them at night, the results could be devastating.
Intake Shutter with Solar Powered Opener
If you are building your own greenhouse, or need ventilation in an existing greenhouse, our solar powered shutters are perfect. They will supply natural ventilation for your greenhouse. They come in 6 sizes and require no electricity. The 4 smaller sizes may be fitted into a polyfilm greenhouse without any further framing. Or, they may be installed in a framed out opening the same as the 2 larger sizes. These shutters are perfect for just about any outbuilding, not just for greenhouses.
Polyfilm Greenhouse with Roll up Side Curtains
A final suggestion for natural ventilation is roll up side curtains. These are typically found in polyfilm greenhouses only, and come with a manual hand crank.
In conclusion, not having electricity in an area where you want to put your greenhouse should not be a deterrent. Use any of these systems, or any combination of these systems to help ventilate your greenhouse. Also, if you don’t like any of these suggestions, another way to go with this is to use solar panels to supply electricity to your motorized ventilation systems.
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