Glazed construction elements are an established technique to transmit light to shaded areas of a building without creating a transparent connection as windows or mirrors do. In particular, glazed elements allow good use of environment-friendly daylight, reducing the need for artificial illumination.

However, to maximise this advantage they would preferably fill entire walls. This requires them to feature effective thermal insulation, and to be able to carry at least their own load – a  combination not available in the market.

Glass bricks filled with translucent silica aerogel offer a new structural load-bearing façade element for perimeter walls with high thermal insulation performance. Aesthetic and durable surfaces for day-lighting possibilities in large areas can be created.

Such contrary requirements are met via staggered spacers between the glass panels, which ensure structural stability along with minimal thermal transmission. The glass brick has a measured thermal conductivity of 53 mW/(m•K) and a compressive strength of almost 45 MPa. This is the highest insulation performance of a translucent brick reported in literature, let alone on the market.

Silica aerogel granules as insulating material offer a unique combination of vapour diffusion openness, super-hydrophobicity, very low thermal conductivity and excellent optical properties.   Their inclusion in glass bricks opens new architectural design options for both the refurbishment of buildings and new constructions with glazed areas.

Translucent glass bricks are suitable for spaces which avoid visual connection from the exterior (for reasons of privacy, security, avoidance of disturbances, etc.) while still bringing diffusive daylight inside.

Examples include libraries, galleries, museums, foyers, offices, staircase cores, gym halls, multi-purpose halls, apartment houses and art workshops

They are also good for spaces where daylight is necessary for healthy circadian rhythm, such as buildings for people (residential homes, hospitals, sanatoria), animals (zoos, stables and animal farms) or plants (green-houses).

Places which require harvesting maximum daylight and space saving, such as in dense cities (high-rise buildings, city apartments); buildings for harvesting heat from sunlight through infra-red radiation (Trombe walls, patios, atriums) can also be suitable application areas.

Empa, the Swiss Federal Laboratories for Materials Science and Technology, has filed a patent for the new glass bricks. For more information, write to Dr Markus Kasper, head of Empa’s Technology Transfer department, at markus.kasper@empa.ch.

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