Vacuum Glass: The Ultimate in Silence and Energy Efficiency

 

Vacuum glass represents a revolutionary advancement in glass processing, functioning like a highly engineered, flattened thermos bottle.

Core Technology:
It consists of two glass panes separated by a mere 0.1-0.2 mm vacuum gap, maintained by microscopic support pillars. This structure eliminates air conduction and convection, making its thermal insulation exceptionally effective.

Key Advantages:

• Superior Insulation: With a thermal conductivity (K-value) often below 0.4 W/(m²·K), it far outperforms conventional double glazing, significantly reducing energy costs.

• Excellent Soundproofing: Its vacuum core is highly effective at blocking low-frequency noise (e.g., traffic rumble), achieving a weighted sound reduction index (Rw) of 36-40 dB or higher.

• Slim Profile: It provides top-tier performance in a much thinner unit, ideal for space-sensitive applications like building retrofits.

Applications:
This technology is key for passive houses, luxury buildings requiring quiet comfort, and energy renovation projects where its slimness is a major advantage.

In short, vacuum glass is a pinnacle of glass processing, offering an unmatched combination of energy savings and acoustic comfort for modern construction.

The Versatile World of Glass: More Than Meets the Eye

 Glass is one of humanity’s oldest and most widely used materials. Unlike crystalline solids, glass is an amorphous material—its atomic structure is disordered, which gives it both transparency and brittleness. Most common glass is made from silica, soda ash, and limestone, melted at high temperatures and rapidly cooled.

The history of glass dates back to around 3500 BCE in Mesopotamia. The Romans advanced glassmaking with blowing techniques, and during the Industrial Revolution, mass production began. A major breakthrough came in the 20th century with the invention of float glass, which made large-scale uniform panes possible.

Today, there are many types of glass designed for different uses:

• Tempered Glass: Heat-treated for extra strength; shatters into small, safe pieces.

• Laminated Glass: Has a plastic interlayer that holds the glass together when broken.

• Low-E Glass: Features a coating that reflects heat while letting light in.

• Self-Cleaning Glass: Uses sunlight and rain to break down and wash away dirt.

• Smart Glass: Can change its transparency with electricity or light.

Glass offers unique advantages: excellent light transmission, chemical resistance, and full recyclability. It’s also energy-efficient when designed for insulation.

Looking forward, glass is becoming smarter and more functional. Examples include energy-generating photovoltaic glass and switchable smart windows. It continues to enable innovations in technology, architecture, and sustainability.

In summary, glass is both ancient and cutting-edge. It’s a material that continues to evolve, playing a key role in modern design and innovation.

Smart glass coating could cool glass buildings

 Researchers at the Fraunhofer Institute have developed a smart coating for building glass that can automatically darken in sunlight. This technology combines electrochromic and thermochromic materials, responding to both electrical stimuli and temperature changes. In modern buildings with extensive glass curtain walls, the coating effectively reduces indoor overheating caused by solar radiation, thereby decreasing reliance on energy-intensive air conditioning systems.

The construction industry is one of the major sources of global greenhouse gas emissions. In Germany, for example, according to statistics from the Federal Environment Agency, the building sector accounts for approximately 30% of the country's carbon dioxide emissions and 35% of its energy consumption. Buildings with large glass facades and roofs, especially office structures, experience sharp rises in indoor temperatures during strong summer solar radiation. Traditional shading devices such as blinds and curtains often compromise visual aesthetics and obstruct views. As a result, such buildings commonly rely on air conditioning for cooling, leading to high electricity consumption and an increased carbon footprint.

To address this issue, the Fraunhofer Institute for Silicate Research (ISC) and the Fraunhofer Institute for Organic Electronics, Electron Beam, and Plasma Technology (FEP) jointly led the EU-funded "Switch2Save" project. They collaborated with universities and industry partners across several European countries to advance the development and application of smart window coating technology.

In this smart coating system, the electrochromic component is based on a transparent conductive film. Applying voltage to the film triggers the migration of ions and electrons, enabling the glass to reversibly transition from transparent to dark. The thermochromic coating, on the other hand, automatically reflects solar heat when the ambient temperature reaches a specific threshold, operating without external power as a passive response mechanism.

The electrochromic elements can be integrated with sensors and a control system to monitor light intensity and temperature in real time. When values exceed set parameters, the system sends an electrical signal to the conductive film, gradually darkening the glass. This effectively blocks heat input and provides anti-glare functionality. On cloudy days or at night, the glass returns to full transparency, maximizing the introduction of natural light.

The technology has already been implemented in practical building applications. For instance, this smart glass system has been installed in the pediatric clinic of a large hospital in Athens, Greece, and an office building in Uppsala, Sweden. Researchers will conduct a year-long energy consumption monitoring study to compare electricity usage of air conditioning systems before and after retrofitting, verifying energy-saving performance under real climatic conditions.

In terms of manufacturing, the team employs wet chemical processes and vacuum coating technology. The electrochromic coating is integrated onto a flexible polymer film, while the thermochromic layer is prepared on an ultra-thin glass substrate. Roll-to-roll production methods enable economical and scalable manufacturing. The final product is only a few hundred micrometers thick and weighs less than 500 grams per square meter, making it easy to install in existing building windows without structural modifications.

Currently, the project team is focused on further enhancing the technology’s applicability. Efforts include combining electrochromic and thermochromic units to improve regulatory flexibility, developing coating processes suitable for curved glass, and expanding color options beyond gray and blue to meet diverse architectural aesthetic needs.

As global warming and the EU Green Deal advance, the demand for energy-efficient building technologies is growing rapidly. All buildings in the EU are expected to achieve carbon neutrality by 2050. Smart window technologies like Switch2Save are poised to play a key role in promoting the low-carbon transformation of the construction industry.