Construction techniques and materials are constantly evolving. In this process, some research teams are seeking to solve some of the most pressing problems, such as achieving greater energy efficiency or integrating functions like climate control or lighting directly into the building elements. Advances like concrete that generates electricity and analyzes buildings , or highly resistant bricks made from egg, are taking construction technology a step further.
Aerobrick Empa Omicron bricks.
Now, researchers at Empa, an interdisciplinary materials research institute based in Zurich, Switzerland, have just unveiled Aerobrick, a new type of translucent brick filled with silica aerogel. This revolutionary building material, described in detail in the scientific journal Journal of Building Engineering, serves the same purpose as traditional bricks but adds the ability to transmit natural light to the interior and offers significantly superior insulation and strength.
In fact, the team led by engineers Jannis Wernery and Michal Ganobjak had already presented an initial version of Aerobrick in 2017, but they have improved its design, composition, and manufacturing process to achieve greater performance. The goal—to be able to build entire translucent walls with effective thermal insulation—is now a reality. These new bricks will thus help save on heating costs, without the need to apply an additional insulating layer to the masonry, and also on electricity, by providing diffused lighting in all types of rooms.
Glass and aerogel
Wernery, Ganobjak and their colleagues in the Energy Materials and Components for Construction department at Empa wanted to develop a material that was true to the principles that the Roman architect Vitruvius considered essential for a building: durability, function and beauty.
To achieve this, they tested different designs, sizes, and combinations, but the main ingredients were always the same: float glass (manufactured by floating molten glass on a layer of molten tin to achieve a uniform thickness and a very flat surface), epoxy resin, and silica aerogel granules. All these materials were selected for their high optical clarity, allowing the maximum amount of light to pass through without the final result being transparent.
After hundreds of computer simulations, the final design took shape with four 12mm float glass panels connected by spacers, with the side, bottom, and top surfaces sealed with a 1.5mm epoxy layer. The spacers were fused directly between the glass panels using silicone molds. This technique allowed the glass to be bonded while simultaneously creating several air chambers between them to optimize thermal insulation.
Aerobrick brick prototype. Empa Omicrono.
To improve its performance, a small opening was left in the seal of each of the six resulting cavities: four in the brick's middle layer and one in each outer layer. These gaps were filled with binderless aerogel granules, and finally, the openings were sealed with transparent tape. The final dimensions of the brick are 500 mm × 136 mm × 84 mm.
Once the first prototypes were obtained, the research team focused on testing their capabilities, both in computer simulations and in the laboratory. Subjected to a hydraulic press, the Aerobrick demonstrated a compressive strength of approximately 45 megapascals (MPa), superior to that of any brick currently on the market.
Regarding thermal conductivity, the aerogel-filled glass brick did not exceed 53 mW/(mK), the lowest recorded value of all those available. Furthermore, it transmits most of the visible light spectrum. Thus, this material could become anew structural element for facades thanks to its high performance and aesthetic qualities.
Use cases
According to researchers, aerogel glass bricks are ideal for spaces that shouldn't have a direct line of sight to the outside for reasons of privacy, security, or to avoid disturbances, but that allow diffuse daylight to enter. The team highlights their usefulness primarily in office buildings, libraries, museums, and other public spaces.
One of the Aerobrick bricks in an industrial press. Empa Omicrono.
They also highlight its versatility in buildings where maximizing daylight and saving space are essential. As an example, they cite densely populated urban neighborhoods with high-rise buildings and numerous apartments—a description applicable to the centers of Madrid, Barcelona, or any other large city. Furthermore, they emphasize the benefits this type of lighting can have on building occupants and their circadian rhythms, referring to the physical, mental, and behavioral changes that follow a 24-hour cycle and are largely regulated by daylight.
In the same vein, regarding healthy circadian rhythms, places like hospitals and nursing homes, as well as zoos, stables, and other animal breeding facilities, are also included. Plants that don't require direct sunlight can also greatly benefit from greenhouses built with this type of brick.
Illustration showing a load-bearing wall constructed with Aerobrick. Empa Omicrono.
Now, while they await patent approval and potential industrial partners, Aerobrick's managers are very proud of a solution that allows for lightweight, thin, and energy-efficient perimeter walls: "We believe that aerogel-filled glass bricks can bring more light into building interiors through the building envelope, while improving health and helping to save energy needed for lighting and heating.".
Source: https://www.elespanol.com/omicrono/.
