The differences between Vacuum Insulating Glass (VIG) and Insulated Glass (IG) (also commonly known as Double or Triple Glazing) primarily revolve around their construction, performance, and applications.
1. Construction
VIG consists of two glass panes with a vacuum between them. The vacuum acts as the insulating medium, preventing heat transfer. A thin edge spacer seals the vacuum space, and often a low-conductivity gas may be used inside.
IG units typically consist of two or more glass panes separated by a spacer filled with air or an inert gas (such as argon or krypton). The gap between the panes is sealed to prevent moisture or air from entering. The insulating medium is air or gas between the panes.
2. Thermal Insulation
VIG offers superior thermal insulation because the vacuum between the panes provides a very low thermal conductivity, significantly reducing heat transfer. The absence of air or gas in the vacuum space minimizes heat loss, making it highly energy-efficient.
IG offers good thermal insulation, but it is generally not as effective as VIG. The air or gas-filled gap between the glass panes provides insulation, but it has a higher thermal conductivity than the vacuum, meaning it's less efficient in preventing heat transfer.
3. Thickness
VIG is much thinner than IG. It typically has an overall thickness of around 20-30mm, making it ideal for applications requiring a slim profile, such as modern architectural designs or energy-efficient windows with minimal visual impact.
IG units are thicker, typically ranging from 18mm to 50mm, depending on the number of panes and the spacer width. The thickness increases with additional layers of glazing.
4. Energy Efficiency
VIG generally provides better energy efficiency due to its low U-value (thermal transmittance), which can be as low as 0.3 W/m²·K. This makes it ideal for passive houses and buildings aiming for high energy performance standards.
IG units are energy-efficient, but their U-value typically ranges from 0.5 to 1.2 W/m²·K, depending on the thickness and type of gas used. While still energy-saving, they are not as efficient as VIG in preventing heat loss.
5. Sound Insulation
The vacuum layer in VIG also contributes to soundproofing, offering excellent acoustic performance by reducing noise transmission.
IG units provide good sound insulation, but their performance may not be as effective as VIG. The soundproofing ability depends on the thickness of the glass and the air/gas space between the panes.
6. Weight
VIG is much lighter than IG because the vacuum layer eliminates the need for a large gas-filled cavity, making it more suitable for large windows and facades without adding significant weight.
IG is heavier, especially with multiple panes and a thicker spacer system. The added weight can be a concern for larger installations.
7. Maintenance
VIG requires less maintenance as the vacuum seal prevents condensation, fogging, or dirt accumulation between the panes.
IG units may experience condensation between the panes if the seal fails, which can be a maintenance issue. However, if the seals are intact, maintenance is minimal.
8. Durability
VIG is highly durable and can maintain its performance over a long period because the vacuum space prevents the typical issues faced by IG units, such as gas leakage or condensation.
IG units can degrade over time if the seal between the panes fails, allowing air or moisture to enter the gap, which can affect the insulation performance.
9. Applications
VIG is commonly used in high-performance energy-efficient buildings, passive houses, and architectural projects where a slim profile and superior thermal performance are required. It is also increasingly used in façades and high-end window systems.
IG units are widely used in residential and commercial buildings as standard windows. They are versatile and cost-effective, providing adequate insulation for most typical applications.
10. Cost
VIG is generally more expensive than traditional IG due to the advanced technology, manufacturing processes, and superior thermal performance.
IG units are typically more affordable, especially for standard double-glazed units, making them a more cost-effective option for many projects.
