Greenhouse coverage
The most important feature of the greenhouse coverage is to ferry the maximum amount of heat and sunlight and deliver it to the plant.
None of the coverage has 100 percent of light and heat transformation; because some of the light is reflected or absorbed into the cover. Among different covers in terms of light passing, glass is in the first rank, and the plastic cover is in the second place.

Different types of the greenhouse cover
Glass cover
The quality of the glass and its dimension is effective in light passing. The more percentage of iron more canescent is the glass and ferry a lower amount of light. The larger pieces of glass are better than the small ones in terms of light crossing. The greenhouse with a glass cover is the most expensive type of greenhouse, and its building and conservation are higher than the plastic cover.
Plastic cover
To cover greenhouses, thin plastic plates are used such as polyethylene, polyester, vinyl polychloride (P.V.C), Polyvinylidene difluoride (P.V.F).
Polyethylene is the most useful one in the greenhouse cover. Almost all of the recent greenhouses are of two layers. Used polyethylene to cover greenhouse, including Anti (UV) ultraviolet radiation. One of the advantages of these covers is that it needs no heavy skeleton, and it decreases the warm-up costs by up to 40% compared to the one-layer glass greenhouses.

Walls and roofs cover(Glass)
The most important feature of the greenhouse is crossing the light. The greenhouse cover should deliver the maximum amount of available light to the plant. So, the percentage of light passing from the cover is an important factor for choosing it. No material can ferry the light 100%. In glass covers, the quality of the glass and its dimension are effective in light passing. The more iron in the glass, the more cane scent is the glass, and less light can pass it.

The features of the glass cover
Larger pieces of the glass are better than the small ones in terms of light ferrying; because they need less iron frame or less wood. So, there will be less shading in the greenhouse. Nevertheless, large glasses are less resistant to the wind and snow and break sooner. The joints between glasses and steel frame transit some air. So, the glass cover provides a bit of ventilation in the greenhouse constantly. It sweats less than the plastic cover due to the emission of extra moisture.
Today, a greenhouse with a glass cover is the most expensive greenhouse. While these structures last for more than 100 years, the high building and conserving costs in addition to the difficulty of establishing them compared to plastic covers, caused many producers of greenhouse products to use plastic cover.

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