Greenhouse Insulation
A method that is popularly employed in building of greenhouses to retain heat is insulation. To keep the heat in, insulate all areas within the greenhouse not intended for heat absorption. To retain the most heat, internal and external insulation are done.
Insulating from within
All the areas that are not glazed must be insulated to keep as much heat as possible within the greenhouse. Seal openings like doors and vents with weather strips to prevent heat from escaping through these openings. When mounting the glazing, insure that it is fitted snuggly in its casements. Fiberglass butt, polystyrene, and polyurethane foams are good insulators although to function well, these materials have to be kept dry. Mounting a polyethylene film between the walls of the greenhouse and the insulation will enhance the capacity of the greenhouse in keeping the heat in.
External Insulation
There are two types of external insulation. When the greenhouse is built on ground level, insulating materials for example, bales of straw, are placed along the wall that are unglazed to prevent the greenhouse from losing heat. Other greenhouse growers build the greenhouse using the side of a south facing hill for natural external insulation. Still other greenhouse growers build their greenhouse in a pit using all the walls in the pit as natural insulators. Underground greenhouses have the best natural insulators, as heat loss will be very minimal. Greenhouses that are built underground provide perfect protection against wind and bad weather. The only possible problems with greenhouses that are built underground are the seeping in of water when the water table is breached. Growers that prefer to use the ground as its insulator minimizes this risk buy building the greenhouse five feet above the water table and creating drains outside the green house to redirect the water away from the walls.
Greenhouse Curtains
These curtains are insulation sheets made of polystyrene that limits the heat lost trough the glazing by as much as 90%. For small greenhouses, these curtains are installed manually and removed in the morning with ease. To facilitate installation, the curtains are furnished with magnetic clips and Velcro fasteners. For larger greenhouses, thermal curtains used are foil backed polyethylene materials, foam backed fiberglass and polyethylene bubble material. Pulleys are used to raise or lower these thermal curtains. Some manufacturers fix their thermal curtains with electric motors to roll the blankets up or down, well suited to larger greenhouses.
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