Vacuum Glass Explained
Vacuum glass is an exciting new product that is working its way into residential and commercial building projects. The technology holds great potential in terms of thermal efficiency and sound reduction. It was first made commercially available in 1996 and has been a popular topic recently.
Vacuum glass is an insulating glass that consists of two or more glass panes separated by a vacuum-sealed space. Unlike traditional double or triple-glazed windows that utilize air or inert gas between the panes for insulation, vacuum glass eliminates the gas altogether, creating a vacuum. This absence of gas minimizes heat transfer through convection and conduction, resulting in significantly improved thermal insulation properties.
The Science
The concept of vacuum insulation is rooted in fundamental principles of physics. Heat transfer occurs through three main mechanisms: conduction, convection, and radiation. In traditional insulating glass, the presence of gas between the panes facilitates heat transfer through conduction and convection. However, by removing the gas and creating a vacuum, vacuum glass virtually eliminates these pathways, drastically reducing heat loss or gain.
Radiation, which accounts for a significant portion of heat transfer, is mitigated through the use of LowE coatings on the glass surfaces. These coatings are designed to reflect infrared heat into while allowing visible light to pass through, maintaining thermal comfort indoors.
Benefits of Vacuum Glass
Enhanced Energy Efficiency- By minimizing heat transfer, vacuum glass significantly reduces the need for heating and cooling of buildings, leading to substantial energy savings and lower utility bills. This benefits homeowners and businesses but also reduces greenhouse gas emissions. Vacuum glass can achieve a R value of 10 where a high end well insulated triple pane window can have a R value of 6.
Improved Thermal Comfort- The insulation properties of vacuum glass help maintain consistent indoor temperatures throughout the year, eliminating cold drafts in winter and excessive heat in summer.
Noise Reduction- Vacuum glass exhibits excellent sound insulation properties, making it an ideal choice for environments where noise reduction is essential, such as urban areas or buildings located near busy roads or airports.
Thinner Insulated Glass Units- Compared to traditional insulating glass units, vacuum glass panels can be thinner while offering equivalent or superior thermal performance. This allows for more streamlined window and facade designs, maximizing natural light penetration and architectural aesthetics without compromising energy efficiency.
Vacuum Glass Challenges
One of the primary drawbacks of vacuum glass is its relatively high initial cost compared to conventional glazing options. The complex manufacturing process and specialized materials involved in producing vacuum glass contribute to its elevated price point. While the long-term energy savings may offset this initial investment, the upfront cost can pose a barrier to adoption.
Optical Clarity- The use of spacers between the glass panes is needed to keep the glass panes separate. The frequency of these spaces in the IGU varies by manufacturer. Because spacers are in the IGU the optical view is compromised.
Transparent Spacers
Traditional Spacers
Durability- There is potential for the glass panes to bow or ripple if the glass is not stiff enough or if not enough spacers are used in the IGU. Viewing from the side is when ripples in the glass are most often observed.
Accidental impacts or improper handling during installation can compromise the integrity of the vacuum seal, leading to air leakage and diminishing its thermal performance. Repairing or replacing damaged vacuum glass units can be costly and time-consuming, requiring specialized expertise and equipment.
Limited Availability and Compatibility- Currently, vacuum glass remains a niche product in the construction market, with limited availability and compatibility with existing window systems.
Maintenance Requirements- Regular inspection and maintenance are necessary to ensure the integrity of the vacuum seal and prevent potential issues such as air leakage or moisture entering the void between panes.
Installation- Installing windows and doors with vacuum glass requires precision and expertise due to its unique design and requirements. Proper sealing and alignment of the vacuum chamber are critical to achieving optimal thermal and structural performance. Installation may be more time-consuming and labor-intensive compared to standard window installations, potentially adding to project costs and timelines.
The Future
Vacuum glass has the potential to be a game changer in the fenestration industry.
Research and development efforts are focused on further optimizing the production process, reducing manufacturing costs, and expanding the scale of adoption. As economies of scale are realized and technological advancements continue, vacuum glass may become increasingly available.
We are keeping an eye on the use of vacuum glass in specifically the Rocky Mountains. Can the vacuum be maintained over the long term when subject to the extremes of our climate?