A new review article published in Engineering offers a comprehensive look at vacuum glazing, a technology that shows great potential in enhancing energy efficiency in buildings. As buildings account for around 40% of society's total energy consumption, improving the thermal performance of glazing is crucial for achieving low-carbon building goals.
Vacuum glazing has gained attention for its heat preservation, sound insulation, lightweight features, and anti-condensation properties. The concept dates back to 1913, but it was not until 1989 that researchers in Australia successfully produced vacuum glazing with excellent thermal insulation performance. Since then, significant progress has been made in its development.
The review covers various aspects of vacuum glazing, including fabrication methods, support pillar arrangements, composite structures, research methods, and energy-saving potential. There are three main fabrication methods: the solder glass edge sealing method, the vacuum chamber edge sealing method, and the pump-out edge sealing method. Each has its pros and cons, but the modified pump-out method seems to be the most promising as it can overcome the drawbacks of high-temperature degradation in the glass powder sealing method and insufficient outgassing in the vacuum chamber method.
Support pillars play a vital role in maintaining the vacuum gap and withstanding external pressure. Their arrangement needs to balance mechanical and thermal considerations. Composite vacuum glazing, such as hybrid, triple, and PV vacuum glazing, has also been developed. Triple vacuum glazing can achieve a very low U-value, indicating excellent insulation performance, while PV vacuum glazing can generate clean electricity by harnessing solar radiation.
To assess the thermal performance of vacuum glazing, researchers use analytical, numerical, and experimental methods. These methods help in understanding the heat transfer processes and evaluating the impact of different factors on the U-value, such as the type of glass, vacuum level, and low-E coating emissivity.
The energy-saving potential of vacuum glazing varies depending on building types, climates, and other factors. In severely cold and cold climates, triple vacuum glazing is highly effective in reducing heat loss. In regions with abundant solar radiation, PV vacuum glazing can significantly enhance building energy efficiency. Tinted vacuum glazing is suitable for areas with significant seasonal variations in heating and cooling demands.
However, there are still challenges to overcome. Further studies are needed on the stability and industrialization of vacuum glazing with aerogel support pillar arrays. Also, determining the appropriate control strategy for tinted vacuum glazing and understanding the aging process of vacuum glazing and its composite structures are important for maximizing their energy-saving benefits. Overall, vacuum glazing holds great promise in contributing to the development of sustainable low-carbon buildings.
The paper "Excellent Insulation Vacuum Glazing for Low-Carbon Buildings: Fabrication, Modeling, and Evaluation," authored by Jinqing Peng, Yutong Tan, Yueping Fang, Hongxing Yang, Aotian Song, Charlie Curcija, Stephen Selkowitz. Full text of the open access paper: https://doi.org/10.1016/j.eng.2024.11.027
