Homemade Solar Greenhouse
Homemade solar greenhouses generally extend the growing season, protect plants from animals and most insect infestation, and allow gardeners to regulate atmospheric conditions. Solar greenhouses absorb and store energy from the sun and release the heat during the night and on overcast days within a well-insulated shell. Build a solar greenhouse with a kit that you put together on site, or follow plans and provide your own materials.
-
Location
-
The key elements for a solar greenhouse are the location, glazing, insulation, large mass heat storage and ventilation.
Place the solar greenhouse where it will receive the maximum amount of sunlight during the cooler months. Check with your local building authorities before you begin construction because many greenhouses are subject to zoning ordinances. If the greenhouse will not sit on a concrete pad, place some form of heavy wire mesh underneath it to prevent burrowing animals from crawling into the greenhouse.
Glazing
-
Glazing is the part of a greenhouse that lets in the sunlight. Choose from glass, polyethylene, acrylic and polycarbonate to act as glazing material. The goal is to maximize the sunlight and heat that pass into the greenhouse while minimizing nighttime heat loss. The Illinois Solar Energy Association recommends that solar greenhouses should have about 3/4 to 1 1/2 square feet of glazing for each square foot of floor space.
Insulation
-
To retain heat, insulate the greenhouse walls. Construct walls that do not receive direct light out of solid materials to make them easier to insulate. The Easy Grow website suggests adding reflective insulation foam boards. Caulk around all seams, doors and openings, and use bubble wrap to add insulation to the glazing.
Thermal Mass
-
Create a thermal mass to absorb heat during the day and to release it at night. Use a large water tank because water is one of the best mediums for retaining heat. If you want to experiment with other materials, the Greenhouse Gardener's Companion website rates steel almost as high as water. Concrete and stone will provide some benefits. A common setup is to create a large tank in the center of a round greenhouse or near the back wall of a rectangular greenhouse. The mass of the tank in relation to the size of the greenhouse is important. Use a tank that holds roughly 2 gallons of water per square foot.
Ventilation
-
The greenhouse needs to be ventilated. Use a fan to help circulate the air. Add vents to a high spot on the roof to let out excess heat. Monitor the heat and humidity levels in your greenhouse and adjust them to accommodate your specific mixture of crops. For example, lettuce plants have a low tolerance for heat compared to pepper plants. A greenhouse full of mature plants generates more heat than a greenhouse filled with seedlings.
-
