Double glazing through the use of Insulated Glass Units (IGUs) significantly improves the thermal performance of windows, keeping warmth in throughout winter and heat out during summer.
Also known as DGUs (Double Glazed Units) IGUs are window units made of multiple glass panels, sealed with a spacer and gas between them.
Glass in an IGU is used to provide natural light and maintain internal temperature conditions and protection from outside conditions.
Spacer Bar – Glass panels in an IGU are separated by a ‘spacer’. Spacers can be found in a number of materials, each of which has an effect on the performance of the IGU. They are often made of aluminium or an insulating plastic composite known as warm edge spacers.
Warm edge spacers get their name because they are more insulating and not as conductive as aluminium spacers. Current available materials are aluminium, steel, stainless steel, thermoplastic, and plastic.
Gas fill – To improve the performance of an IGU, gas filling is an option provided by manufacturers. Inert gasses such as Argon and Krypton are used in place of just air in the internal cavity of the unit.
Hot Air always moves towards cold air. By reducing the loss of heat from the warm side to the cold side of the window, IGU’s can reduce the heat loss in cold weather, or vice versa.
VLR: The percentage of visible light that is reflected from the glass surface(s).
VLT: Expressed as the percentage of visible light that is transmitted through a glass type
SHGC: Solar Heat Gain Coefficient. The proportion of directly transmitted and absorbed solar energy that enters into the building’s interior. The lower the number the better the glass is able to exclude solar radiation.
If you require sound proof glass, IGUs have many benefits compared to single glaze windows, one of which is its sound insulating ability. Changing the thickness of glass used in the IGU or combining a laminated glass panel can greatly improve the insulating properties of the IGU.
Compare the sound insulation characteristics of the following configurations:
Configuration 1:
• This would have the least amount of sound insulation.
• 6mm Clear Float window has a rating of 31 (Rw)
Configuration 2:
• This would have a better sound insulation, but not the best.
• 6mm + 12mm spacer + 6mm IGU has a rating of 34 (Rw)
Configuration 3:
• This build up uses glass panels of different thicknesses. Due to the change of thickness the frequency dampens significantly when passing through, giving improved acoustic performance.
• 10mm + 12mm spacer + 6mm IGU has a rating of 36 (Rw)
Configuration 4 – Optimal IGU Configuration:
• This build up provides even better performance in sound insulation and a thinner and lighter IGU. The build-up uses an acoustic laminate glass to provide better acoustic performance and an overall thinner and lighter IGU.
• 6mm + 12mm spacer + 6.5mm IGU has a rating of 38 (Rw)
Rw: Weighted Sound Reduction Index. It is a number used to rate the effectiveness of a soundproofing material. The higher the Rw number, the better a sound insulator will be.
