Saint-Gobain SageGlass

Let there be light!

The intelligent glass manufactured by Saint-Gobain SageGlass combines well-being, climate protection, and extreme efficiency. Bühler is not only the technology partner for the manufacture of these smart windows, but also a customer – the façade of its new CUBIC innovation campus in Uzwil, Switzerland, is fitted with a dynamic outer shell. 

SageGlass is transparent, but controls glare; it is coated, but it’s possible to adjust its tint; and it lets in sunlight on cool days, but blocks it on hot ones. It may cost a little more, but its extreme efficiency and ability to dramatically reduce energy makes up for it. It’s unique. To make the distinction clear, CEO Alan McLenaghan says: “SageGlass is not just another type of glass. If people think of it that way they are not being imaginative enough. It’s all about the dynamic benefits it brings to the people who are occupying the space.”

Nanometer-thin coatings breathe intelligence into the amorphous, transparent glass body: equipped with sensors and software, the glazing adjusts its tint depending on the solar radiation and light, allowing an unrestricted view to the outdoors at all times and under any conditions. It automatically controls daylight, glare, and energy consumption entering the building − and it allows manual adjustment if the occupant wants to override the building management system.

With the advantage of SageGlass, curtains, roller shades, and blinds have become the glare protection of the Stone Age. “Using this as a basis, architects have the opportunity to use glass in ways and applications they previously could never have imagined,” explains McLenaghan. SageGlass allows architects and designers to create buildings that optimize the use of natural daylight while providing unobstructed views to nature and the world outside. For thousands of years, our forefathers lived mainly in the great outdoors. Still wild creatures from a genetic point of view, modern urbanites also need sunlight for their health and well-being.

For office buildings, there is ample evidence that sufficient daylight brings improved satisfaction in the workplace, reduces stress and absenteeism, improves the quality of sleep and perceived well-being, and increases productivity. In hospitals, it has been observed that patients in rooms with a view and optimized daylight required less pain-relieving medication and their recovery was accelerated. For schools, it has also been proven that daylight and views to the outside promote concentration and attention in students, resulting in increased retention and improved test scores. 

Enhanced productivity and well-being

Even our environment benefits from the intelligent SageGlass. Up to 35 % less energy is required to heat and cool buildings regulated by SageGlass. This also has a CO2 benefit of up to 10 %. Operationally, SageGlass replaces the need for blinds or other solar shading devices, resulting in annual cost and environmental savings by eliminating maintenance and replacement of traditional materials. As a result, the value of the real estate and the rental income increases.

Despite the higher initial investment of up to 1 % of total construction costs, SageGlass calculates a return on investment of less than 10 years, based on energy savings alone. If other factors are considered, such as the glare protection that is no longer required, and the enhanced performance and well-being of the occupants, the return is realized even more quickly. “Our products are not a panacea for all problems, but they certainly enhance productivity, well-being, cognitive capability, and efficiency,” says McLenaghan.

SageGlass was an obvious choice for Bühler in building its CUBIC innovation campus. “In the CUBIC, we want to connect people and let ideas flow freely in order to make those ideas become real solutions more quickly,” says Bühler CTO Ian Roberts. Equipped with SageGlass, the CUBIC is open, transparent, and filled with light – in and of itself a source of inspiration for the employees, project teams, and start-ups inhabiting its space.

The basic principles of electrochromic coating have been known since the early 1960s. It consists of molecules or atoms that can change their optical properties with a flow of electricity. In the case of dynamic glass, this involves lithium ions and electrons. Applying voltage of only 5 volts creates a low current, moving lithium atoms from one layer to another, creating a darkening effect. The actual art here, originating from this chemical and physical principle, is to manufacture large high-quality products on an industrial scale to look exactly the same, function flawlessly for 30 years or more, and to work together like a fully synchronized water ballet. With more than 500 patents, granted over the past 20 years, Saint-Gobain SageGlass has taken this art to new heights – and Bühler has been a significant technology partner in this.

We selected Bühler because of their technical advancement, the innovation that they bring, and their willingness to work with us on design changes.

ALAN MCLENAGHAN, CEO, Saint-Gobain SageGlass

A close partnership

In 1989, John Van Dine founded the company in Valley Cottage, New York. Technology and processes were developed to market readiness, and the first product was launched – the starting point for rapid growth. The average rate of growth has been more than 50 % a year; SageGlass is now installed in buildings in 30 countries.

After a period of close partnership with Saint-Gobain, the global market leader for construction materials took over the company in 2012, complementing its own electrochromic technology with that of SageGlass. Since then, SageGlass has been a wholly-owned subsidiary of Saint-Gobain. In 2010, a close partnership was formed between SageGlass and Bühler.

“SageGlass and Bühler had a symbiotic relationship from the beginning,” says McLenaghan. The company’s expansion required a new factory which SageGlass built in Minnesota – and with it, new coaters. “The first coaters used in our expansion were Bühler coaters,” says McLenaghan. “We selected Bühler because of their technical advancement, the innovation that they bring, the similar culture of the companies and Bühler’s willingness to work with us on design changes we needed in the coater.”

The stringent requirements were not to be met with a standard system. In order to achieve the desired characteristics, a vertical arrangement of the machines was needed instead of the usual horizontal layout. An additional criterion was easier access to the key components of the machine to make maintenance and cleaning easier.

The specially developed behemoth of a machine, with dimensions of 75 x 15 meters, met the enormous demands with the highest reliability, and coats more than 1,500 square meters of glass per day with the precision of just a few atomic layers – typically up to six coats were applied for this. Temperature curves, vacuum, material deposits on the glass: all of this was controlled perfectly by the GLC 1850 V Large Area Coater from Bühler Leybold Optics.

Although the factory and coater are still relatively new, it is already foreseeable that they will reach their limits. “We are already considering a new production location which would undoubtedly be somewhere outside the US,” says Alan McLenaghan. 

Our products are not a panacea for all problems, but they certainly enhance productivity, well-being, cognitive capability, and efficiency.

ALAN MCLENAGHAN, CEO, Saint-Gobain SageGlass

How SageGlass works

Electrochromic glass works similarly to a battery: in the transparent/translucent state, lithium-ions are embedded in the storage layer. If voltage is applied, the lithium-ions are transported through the electrolyte to the electrochromic layer, and the glass darkens: heat and light are then reflected. The electrodes for application of the voltage are transparent in order to allow light to pass through. By applying counter voltage, the lithium-ions are transported back, and the electrochromic glass becomes transparent again.

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