SAGE Electrochromics, Inc. SAGE Electrochromics, Inc. - Frequently Asked Questions

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What is electrochromic (EC) glass?

It is electronically tintable glass that can be switched from clear to darkly tinted (and from darkly tinted to clear) at the push of a button. EC glass can be operated manually or integrated into an automated building management system. SageGlass® EC glass modulates visible light transmission and solar heat gain, and, in the tinted condition, blocks 98% of the total solar radiation that causes fading.


How does SageGlass technology work?

SageGlass panes are coated with five layers of ceramic materials, which have a total thickness that is less than 1/50th that of a human hair. When voltage is applied across the coatings, ions travel from one layer to another layer, where a reversible solid-state change takes place, causing the coating to tint and absorb light. Reversing the polarity of the applied voltage causes the ions to migrate back to their original layer, and the glass returns to its clear state. SageGlass technology is described in more detail on the Technology page.


How is SageGlass manufactured?

SAGE coats conventional float glass with layers of metal oxides using a vacuum deposition process called “sputtering,” which is the same process used to make hundreds of million square feet of low-e and double low-e glass each year. The coated SageGlass pane is then fabricated into an insulating glass unit (IGU) with another piece of glass (clear, tinted or laminated) and a stainless steel spacer.


Are there intermediate tint levels?

The standard control systems currently provided switch SageGlass® from its clear state to its tinted state and vice versa. We are currently developing systems that control the glass to intermediate levels of tinting. We expect to offer this system as a standard product in 2010.  Please contact SAGE’s personnel for more information.


What control system options are available?

The SageGlass product is supplied with a standard panel-mounted control system.  This control system can be operated by the user via a simple wall switch or integrated into a variety of different building management control systems, such as lighting, energy management, audio visual and security systems. When integrated in such a manner, SageGlass windows and skylights are controlled by inputs from, for example, timers, light sensors, motion sensors, lighting control and thermostats. 


Can SageGlass products be controlled wirelessly?

Yes, many building management control systemsinto which SageGlass products can be integratedhave remote control capabilities.


Can SageGlass be powered with photovoltaics (solar cells)?

Yes, PV-powered SageGlass IGUs are under development.  Because of their low DC voltage and power consumption, and the obvious complementary relationship between the amount of sunlight available and the level of tinting required to modulate it, SageGlass products are excellent candidates for PV power.


How fast does the tint level change?

Most of the tinting occurs in 3-5 minutes, depending on glass size and temperature of the glass.  Faster tinting can occur in smaller panes and/or warmer temperatures.


What colors are available?

SageGlass IGUs come in four standard colors (the colors are a function of the inboard lite): Classic, See Green, Cool View Blue and Clear as Day Gray. A chart detailing the performance of these four colors is shown on our Products page. SageGlass products can also be ordered with a custom inboard lite, which can be of a chosen color, laminated, fritted, or in other ways non-standard.

Please note that the differences among the colors can be seen in the light transmitted into the space, whereas the exterior reflected color varies little, no matter what color the SageGlass IGU is. This is because the coated SageGlass pane is the outboard lite in the IGU.
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What is the uniformity between panes? Will they all look the same?

As with any coated glass, there will be small color and tint level variations. The inherent dynamic nature of SageGlass products implies that different panes may be deliberately placed in different states (clear versus tinted) and will therefore have a different appearance while providing a desired benefit.  The unique dynamic nature of SageGlass products and the significant energy and comfort benefits derived from its changeability (adaptability) suggest that conventional forms of comparison may not always be appropriate.


Can you match the SageGlass colors with the color of other glass in the building?

Two pieces of glass from different sources rarely match exactly.  If glass from two sources is installed in separate areas of the building, a slight mismatch is often unnoticeable.  If there is not a separation on the building between the two types of glass, the SageGlass product can be ordered in a color that is complementary to the other glass products being used in the building.


What is the largest available size of SageGlass products?

The largest size currently available is 40" x 60" (in either dimension, W x L, or L x W).

An important point to keep in mind with SageGlass products is that they allow for tinting of the glass to be controlled in zones, which is desirable because the sun's glare is directional. This introduces the opportunity to design with glass in such a way that it can be programmed to “track” the sun as it moves around the building. In this scenario, smaller panes can be desirable by providing more zones of control within a given glazing area.   The greater the number of zones, the greater the opportunity to optimize and balance glare, daylighting and energy issues.


How does the cost compare to low-e insulated glass?

Because in most installations, SageGlass products eliminate the need for interior and exterior blinds and shading systems, glass-to-glass price comparisons are not appropriate. The reduction of other costs must also be considered given the unprecedented benefits provided by the SageGlass product.

Until now, glass and its necessary solar control devices were two different things. With SageGlass products, the glass IS the solar control device. Moreover, SageGlass products conserve energy and reduce first costs (smaller HVAC systems, for instance, can be used in many situations). Building maintenance costs are also lower because HVAC systems run less often, and there is no need to replace or repair shades and blinds.

The bottom line is traditional methods of controlling sunlight and heat can easily cost the same or more than SageGlass glazing. And dollars are only part of the equation: SageGlass glazing conserves energy while preserving the view and connection to the outdoors which is the reason we put glass in buildings in the first place.

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What happens when a building has a power outage?

When power is removed, SageGlass products gradually revert to the clear (untinted) state.


Do SageGlass products provide privacy?

SageGlass products provide some privacy because they transmit less than 4% of the visible light in their tinted state. On a sunny day, when the windows are in their tinted state, it is nearly impossible to see through the glass when looking in from the outside. However, the purpose of SageGlass windows and skylights is to provide solar control without blocking the view from the interior to the outside therefore even in their tinted state they are transparent (unlike “privacy glass” which turns opaque) so they do not provide 100% privacy. For example, at night, when the lights are on inside the building, someone on the outside could see distinct images on the inside, even when the windows are in their tinted state.


What shapes are available?

Today we offer rectangles and squares, as well as selected straight-sided nonrectangular shapes including parallelograms, trapezoids and certain types of triangles. We are continuing to expand our product line so please contact SAGE’s department with your project information so that we can evaluate the availability of a particular shape.


Do SageGlass windows and skylights help attain LEED credits?

Yes, SageGlass products provide an additional tool for daylighting design and also conserve energy. The LEED credits that SageGlass products could help you earn for your project are listed on the Green/LEED page.


Where have SageGlass products been installed?

SageGlass units have been sold into commercial and residential applications since 2003. We have projects throughout the U.S., and in Europe and other countries. A few of these projects are shown on our Project Gallery page.


What is the dynamic range of the glass?

SageGlass Classic IGU can be varied from 62% visible light transmission in its clear state down to 3.5% in its tinted state, with a solar heat gain coefficient that varies from 0.48 on the high end to 0.09 on the low end.  The performance of our five standard products is shown in the chart on our Product page.


Where is the SageGlass coating?

In the majority of applications, it is on surface two (the inside surface of the exterior lite). In this location, the SageGlass coating blocks solar heat before it ever gets inside the building, which means there is significantly less heat that needs to be removed by the HVAC system. By contrast, shades and blinds do not block heat from entering buildings. A building occupant might not feel heat directly on him or her if the shades are drawn, but the heat still gets in and must be removed by air conditioning.


What is the lead time for SageGlass products?

Lead time will vary due to a variety of factors, but typically 12 to 16 weeks. Please contact SAGE for specific lead times.


Are SageGlass products considered “low-emissivity”?

Yes, the SageGlass coating has a low-e surface so it provides all of the advantages of a spectrally selective low-e (even in its clear state). The low-e properties also reduce thermal heat loss during the winter.


What are the SageGlass system power requirements?

SageGlass products consume little power.  It takes less electricity to power and control 1,500 square feet of SageGlass glazing (approximately 100 windows) per day than it does to power a 60-Watt light bulb.
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Has SageGlass technology been tested? How durable is it?

SageGlass technology has undergone rigorous performance and durability testing both in-house and through independent third parties including the U.S. Department of Energy (DOE) and leaders in the glass fabricating and OEM skylight industry.  SageGlass IGUs were the first and only products to pass the ASTM E-2141-06 (Standard Test Methods for Assessing the Durability of Absorptive Electrochromic Coatings on Sealed Insulating Glass Units). In fact, the SageGlass technology survived over 100,000 cycles of accelerated environmental durability testing, which is twice the test standard and equivalent to switching a window nine times per day for 365 days/year over a 30-year lifetime, according to the DOE’s National Renewable Energy Laboratory. Full details are available on our Testing page.


Is there a warranty on SageGlass products?

SAGE warrants the SageGlass IGU for up to 10 years depending on the building application; the electronics and electrochromic functionality carry a five year warranty. For full details on our product warranties, contact our .


What happens if a SageGlass pane gets broken?

SageGlass IGUs are easily replaceable.  If the glass gets broken, it can be deglazed just as ordinary glass is, and simply unplugged. A new IGU can be installed and reconnected to the low-voltage wiring via a simple snap connector, which resides in the glazing pocket.


Where can I buy SageGlass products?

Information for Commercial sales can be found here, and for Residential sales, here. If you prefer to email or phone the SAGE Sales team, please write to or call . A SAGE sales representative will promptly respond to your inquiry.


Can I prewire my windows? 

Yes.  Please contact SAGE’s Customer Solutions department at or for more information.


What framing systems can be used with SageGlass IGUs?

Most frames that use hollow aluminum extrusions and wood window systems will accept SageGlass IGUs.  We recommend providing a 5/8” perimeter coverage on the glass, and sufficient room in the glazing pocket to accommodate the slimline snap-together connector.  SAGE has partnered with several leading window, skylight and curtainwall manufacturers for integrating SageGlass products into their framing systems. These companies are listed on our Partners page. In addition, SAGE will work with suppliers chosen by the architect or builder to develop integration solutions.


Are there any commercially available switchable technologies for exterior solar control building applications other than SageGlass products?

The SageGlass product is the only one to have passed the stringent ASTM E-2141 standard for windows (please see question number 24).


What are appropriate applications for SageGlass® products?

SageGlass products are used in residential and commercial windows and doors, skylights and curtainwallsanywhere there is a desire to bring in natural daylight while maintaining a comfortable interior environment and an uninterrupted view and connection to the outdoors. Because of the energy they conserve, SageGlass products are appropriate in sustainable building designs. Moreover, its fading prevention makes SageGlass glazing ideal for applications where the protection of the interior is desired.

The following list highlights some applications that lend themselves particularly well to the SageGlass glazing solution:

·      Green or LEED buildings

·      Owner occupied office space

·      Museums and libraries

·      Health care

·      Religious facilities

·      Atrium, skylights, and overhead glazings

·      High-technology or image buildings

·      Aviation facilities

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