Translucent Concrete and Smart Glass for Sustainability and Privacy Control

Translucent Concrete and Smart Glass could together offer architects a creative tool to ‘switch off the wall’ on-demand in net-zero buildings, thus contributing to the goals of the European Climate Law.

Translucent Concrete

Patented in 2001 by Hungarian architect Áron Losonczi, the undeniably smart material called ‘translucent concrete’ (also called ‘light-transmitting concrete’) is made from the traditional mix of water, sand, gravel and cement, enhanced by plastic or quartz fibres embedded throughout it’s bulk.

The end result is an architectural and design tool which transmits and scatters daylight throughout a building, offering energy efficiency, sustainability and privacy, as well as serving as a structural and insulative element.

Translucent concrete is usually delivered as prefabricated blocks or panels, where each block incorporates thousands of these optical elements, oriented perpendicular to the face of the facade, allowing light to be transmitted from the outside in, and vice versa.

End-products created with translucent concrete include exterior walls, internal partition walls, staircases, decorative tiles and even furniture.

Passive vs Active Smart Materials

There are some similarities between translucent concrete and ‘passive’ smart glass technologies such as thermochromic and photochromic smart glass, in that neither can change their behaviour after manufacture.

Thermochromic smart glass changes its transmittance based on changes in temperature, whereas photochromic smart glass depends on UV and visible light.

All the above can contribute positively to green building credits, since standards such as LEED v4 require a minimum of 300 lux of daylight throughout 50% of the building space.

Using translucent concrete could then allow more daylight to permeate the building envelope, while still reducing heat gain and lowering air conditioning costs in warmer months.

On the other hand, ‘active’ materials such as PDLC, SPD and electrochromic smart glass can change their behaviour in real time because they are driven by an electrical stimulus. They can be controlled for example via sensors or building automation systems.

They can also contribute to LEED v4 credits but require electrical power, which can offset the benefits of reduced artificial lighting.

Net-Zero Buildings

When it comes to sustainability, translucent concrete allows natural daylight a way to penetrate deep into building interiors that might otherwise lack any light at all.

Additionally, when used with artificial lighting, translucent concrete can facilitate creative designs for retail and residential properties.

The “Energy Performance of Buildings Directive” from the European Union requires all new buildings to be ‘nearly zero-energy’ by the end of 2020, and mandates the use of renewable energy sources.

The aim of this EU Directive is to “promote the improvement of the energy performance of buildings within the EU, taking into account outdoor climatic and local conditions, as well as indoor climate requirements and cost-effectiveness”.

It is clear that translucent concrete would contribute positively towards these goals.

Composition of Translucent Concrete

Typically, the optical fibres inside translucent concrete constitute about 4% of the total mix, thus leaving a product which is lower in weight and yet with a tensile strength of around 70 MPascals (or 10,000 psi).

The materials can be customised by choosing the density and diameter of the optical fibres and this modifies the transmittance (i.e. the amount of light) that the material lets in.

The fibres suffer minimal loss of light within a distance of about 20m.

Manufacturers of Translucent Concrete

Manufacturers of translucent concrete include Litracon, Lucem, Zospeum and Luccon.

In particular, Zospeum’s differentiating factor lies in their insulative core, which gives additional thermal resistance, reducing solar gain and energy costs.

Combining Translucent Concrete and Smart Glass

If you consider combining translucent concrete with smart glass, we open up the possibility of ‘switching off’ the natural light whenever needed.

This could be implemented with a layer of smart glass, affixed on the interior face of the translucent concrete and running at 110Vac, thus allowing light to come in. The power requirements are in the range of 5W per square metre, which is minimal.

Whenever users need to ‘switch off the wall’, they can simply switch off the smart glass, blocking any incoming daylight.

This feature could be useful for corporate offices, retailers, healthcare, and residential constructions which need to control incoming light during the daytime and throughout the year.

The closest idea we can get is by looking at an installation of SPD smart glass by the market leader, Gauzy, who kindly shared the images below with us.

Gauzy SPD smart glass in airport terminal

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