Insulated Glazing Units

Insulated Glass, often called double glazing, is a combination of two or more panes of glass spaced apart with a spacer bar and hermetically sealed with a primary and secondary sealant to form a single unit with one or more air spaces in between. IG units improve the thermal performance, thus significantly reducing heating and air-conditioning costs. IG units also reduce probability of  condensation formation on the surface of the glass.IGU can be a combination of Low-E coatings, tinted glasses, reflective coatings, silk-screened patterns, laminated glass products and more.  A wide variety of insulating glass configurations are available to satisfy a variety of performance and aesthetic requirements. 
IG units can be fabricated to meet state energy codes, sound control requirements, impact resistance, bullet resistance, and hurricane & blast resistance requirements. IG units can be designed to reduce heat loss & solar heat gain and reduce thermal heat gain entering the building, with a minimal reduction of visible light transmittance.
Characteristics of Insulated Glazing Units
Thermal Properties: The U value is effectively lowered by insulating glazing and can be further reduced by filling of inert gases, generally increasing cavity thickness and using inert gases like Argon or Krypton or Xenon to further improve thermal insulation
Acoustical insulation: Insulating glazing can reduce noise by about 30dB (5mm glass- 12mm air gap -5mm glass) and further reduction is obtainable by using asymmetrical combination and using laminated glazing.
Condensation: IGU reduces the probability of condensation formation compared to monolithic glass.
Sealing: Two glasses are separated by a spacer which is generally made of aluminum; primary sealant and secondary sealant are used for air and water tightness.
Benefits of Insulated Glazing Units
Energy Conservation:
The table given below, shows how insulating glass helps in conserving energy in hot climate, as compared to monolithic glass.

Monolithic Glass

Insulating Glass

Monolithic glass such as annealed glass is a single glass.

Double glass such as IG, contains hermetically sealed dry air space between the sheets of glass.

It gets heated directly by sunlight.

Double glazing prevents direct contact with sunlight.

When air conditioner is used inside the building, the temperature difference between the inside and outside the building is very high.

When air conditioner is used inside the building, the temperature difference between the inside and outside of the building is very less.

There is only a thin glass barrier to prevent the outside heat from coming in - resulting in excessive loss of energy.

Due to convection, air circulates inside and acts as a barrier, preventing outside heat from coming inside and the cool air inside from escaping - results in energy saving.

Perfect Transparency:
Insulated glass units help in reducing the incidence of condensation on the warm air side and brings about transparency. IG can be used in larger glazed areas without increasing energy consumption and still bring about perfect transparency. Insulated glass is used in soft drink chillers in retail stores, airports, etc.
Reduced Infiltration:
In hot climates, heat gain due to temperature difference is reduced by IGU.
Reduced Condensation:
Water from condensation build-up and the resultant water run-off can damage window sills and frames, and seep into walls and adjoining areas. Condensation will form when the moisture in the air condenses out on surfaces that are cooler. Window surfaces being colder than other surfaces in the building are more prone to condensation build up. An IGU reduces the likelihood of condensation forming by providing a thermal barrier between the inside and the outside.
Applications of IGU:
Insulating glass (IG) units are used in a wide range of applications including:
  • Commercial/Residential Fixed and Operable windows
  • Curtain Walls
  • Storefronts
  • Sloped/Overhead Glazing
  • Non-vision (Spandrel) Locations