How to Use Solar Heat in Northern Greenhouses
A greenhouse is a solar-heated system by definition. Glass panels allow solar energy to enter and trap a portion of that energy inside the enclosure to keep plants warm. But you can improve on this effect by using thermodynamic and solar-efficiency techniques. Add some common-sense maintenance steps and your plants will pass the winter in comfort. Does this Spark an idea?
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Things You'll Need
- Greenhouse
- Glass panels (if needed for repairs)
- Clear plastic sheet (if needed for repairs)
- Insulating door sealant strips
- Clear adhesive caulk
- 55-gallon plastic drum(s), preferably black
- Flat black paint
- Water
- Paint brush
- Mylar thermal blanket
Instructions
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Repair any broken glass panes (or torn plastic) before starting any other steps. A greenhouse with open panels or walls simply will not hold in heat.
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2
Apply or replace the insulating door strips to ensure the seal around your greenhouse door(s) is tight and will keep warm air inside.
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Use clear adhesive caulk along all wall and roof joints and on any possibly leaking panel joints to complete the tight seal of your greenhouse.
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4
Place the 55-gallon plastic drum at a point not touching the wall, but fully exposed to the maximum amount of sunlight throughout the day.
If the drum is not black, paint it black. Fill the drum with water.The rule of thumb is to use 2 gallons of water per square foot of greenhouse. Add drums if your greenhouse floor is larger than 27 square feet. This water will store a portion of the energy trapped inside the greenhouse and will release it overnight. Extra thermal storage won't hurt your greenhouse.
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Paint any interior surfaces (not the glass or plastic greenhouse panels) flat black to increase the absorbed energy.
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Place (if practical) the Mylar sheet outside your greenhouse and angled to reflect sunlight onto the greenhouse.
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Tips & Warnings
The website Greenterrafirma.com (see References) shows three relatively simple methods to use solar techniques to heat air to add into your greenhouse.
References
- Photo Credit Metal greenhouse in summer with open door image by Scott Latham from Fotolia.com
