Covering/roofing materials

• The following factors are to be considered while selecting the greenhouse covering material i.e., light, transmission, weight, resistant to impact, and durability to outdoor weathering and thermal stability over wide range of temperatures.
• The purpose for which greenhouse facility is intended and service life of material should be considered before selecting the covering materials
• In temperate regions where high temperatures are required, the covering material with high light transmission and far IR absorption must be selected.
• Also the loss of heat by conduction should be minimum.

Estimated life of covering materials

Properties of ideal covering materials

• It should transmit the visible light portion of the solar radiation which is utilized by plants for photosynthesis.
• It should absorb the small amount of UV in the radiation and convert a portion of it to fluoresce into visible light, useful for plants.
• It should reflect or absorb IR radiation which are not useful to plants and which causes greenhouse interiors to overheat.
• Should be of minimum cost.
• Should have usable life of 10 to 20 years.

Light transmission of covering materials