Chapter 2

Greenhouse Glazing

(book excerpts)

The greenhouse glazing, or glazing as it is referred to in the industry, represents the greatest decision in selecting the design for the greenhouse. The selection of a glazing is crucial for attainment of an optimal controlled environment, particularly relating to the solar radiation intensity and the type (diffuse/direct and partial or full­spectrum of the sun) of solar energy that reaches the plants inside the greenhouse. Diffused light is better than direct light. Various glazing materials have radically different response to environmental conditions such as solar irradiance, wind, snow, and hail; and are by virtue of composition and manufacturing parameters quite different in physical properties. Key characteristics that should be considered in selecting glazing is the cost, its durability (how long it lasts), its weight and ease of repair or replacement, how much light is transmitted through the material, transparent versus translucent, and how much energy moves through the material. Greenhouse glazing can be divided into three groups; plastic films, rigid plastics, and glass. The plastics can be further subdivided into generic materials such as polyvinyl chlorides, polyethylenes, polypropylenes, fiberglass, polycarbonates, acrylics, and polyesters, to name a few.

Click on the following topics for more information on greenhouse glazing.

Topics Within This Chapter:

  • Types of Greenhouse Glazing
  • Plastic Films
  • Polyethylene Film
  • Tefzel Film
  • Polyvinyl Chloride (PVC) Film
  • Polyester
  • Rigid Plastics
  • Fiberglass-Reinforced Plastic (FRP) Rigid Panel
  • Polycarbonate
  • Polymethyl Methacrylate (PMMA) or Acrylic
  • Plastic Material Additives
  • Anti-Condensation Inhibitors
  • Infrared (IR) Blocking Plastic Materials
  • UV-Blocking Materials
  • Anti-Dust Inhibitors
  • Light Diffusion Materials
  • Glass
  • Advantages and Disadvatages of Glass
  • Types of Glass
  • Properties of Greenhouse Glazing
  • Photosynthetically Active Radiation (PAR) Transmission
  • Direct and Diffused Radiation
  • Heat Loss
  • Thermal Transmission
  • Life Expectancy