Dynamic Solar Control with Electrochromic Glazing  

Allowing sunlight into buildings has been an important design consideration for centuries. Appropriately controlling that sunlight however has been the focus of many different efforts, particularly in recent times. The attention has been placed on harvesting the desirable characteristics of sunlight in a building while being able to reject or dampen the undesirable characteristics. Achieving that balance has taken on many forms from controlling the orientation of buildings, to using exterior overhangs or interior blinds. It has also included the use of glass and glazing that is treated or coated to have certain light and heat transfer characteristics. All of these solutions have been fixed or static solutions meaning that they have very little or no adjustability beyond their initial installation. But today, electrochromic glazing has changed that and offers a new design solution that is truly variable or dynamic.

Electrochromic Glazing: Glass at a New Level

Abundant natural daylight has consistently been regarded as a key factor in the design of sustainable buildings. The reason is the powerful impact it has on the occupants of those buildings. People respond positively to natural light, views, and the connection to the outdoors that windows provide. In fact, a 2009 study conducted by Pike Research entitled “Energy Efficiency Retrofits for Commercial and Public Buildings” found that “ ...office workers, teachers, and students love green buildings…they attend work and school more regularly, are sick less often, and are more productive...” This study and many others have confirmed what most of us know instinctively—people feel better and perform better in spaces where there is abundant daylight.

There is a difference between being in a pleasantly daylit space compared to having direct sunlight shining in your eyes. We put windows in buildings for a reason; however, the intensity of the sun and the potential for bright spots or glare make the space uncomfortable for occupants. Bright spots and glare are particularly an issue in rooms where computer monitors or similar screens are commonly in use such as office buildings, schools, higher education, and even residences. In addition, regular exposure to direct sunlight causes many materials to wear and fade, thus shortening their life and compromising their inherent qualities such as color, texture, and durability.

Controlling sunlight penetration through glazing is possible at different levels and on different windows using electrochromic glass. Photo courtesy of SAGE Electrochromics, Inc.

 

From an energy standpoint, sunlight generates solar heat gain. In northern U.S. climates during the heating season, harvesting that sunlight and allowing it to transform into useful solar heat energy can be desirable and sought after. But for the rest of the year and in southern U.S. climates that solar heat energy will still be working during months when cooling is the desired mode. Hence, rejecting that solar gain caused by the sun then becomes more important. So, while glass and glazing may be desirable for daylight and outdoor views, traditionally there has been a distinct tradeoff between daylight and solar heat gain as window to wall ratios increase.

The key to good window design in buildings, then, is to find ways to balance both the amount and characteristics of glazing so the daylight, view, and energy benefits are maximized while the glare, fading, and energy penalties are minimized. Conventional design approaches to find that balance have included some very specific strategies—each with their own pros and cons:

Interior blinds and shades. For most situations, this is probably the most common strategy. Mounting adjustable blinds or shades inside the glazing changes the amount of glare that a person experiences inside the building, but also lowers the amount of light and covers the views. In that case, the benefits of having windows are lost but the energy costs continue. Further, in large settings, it is common that once the blinds or shades are set to a particular position, they are often left there beyond the time intended, further reducing the benefits of the windows. From a cost standpoint, these products often require significant amounts of energy to produce, maintain, replace, and dispose of over the course of their life. And since they are notorious for collecting dust, they require regular cleaning and maintenance which has its own ongoing cost. If the option of automatic controls is added to raise and lower shades for example, that does help with maintaining some of the benefit, but at a notable additional cost.

Fixed exterior shading devices like the ones shown here cannot adjust to changing weather and light conditions. Photo courtesy of SAGE Electrochromics, Inc.

Exterior shading. Rather than trying to control light from the inside, it has become popular to look at exterior design strategies. These have included things like adding fixed shades, shutters, or awnings to a building façade which can help reduce solar gain, but are very limited based on the angle of the sun in the sky. They can also require considerable design effort and expertise to have them effectively integrated into a building so they perform as intended without blocking views or too much light. They are usually rather expensive items not only for their initial cost, but also in terms of their life-cycle costs of production, maintenance, replacement, and disposal. Since they are usually fixed in place, they do not adjust to changing light conditions from weather or from adjacent buildings/terrain.

High-performance glass. There have been a series of advancements in glazing technology in recent years that allows for the selection of glass that has different thermal and light transmittance properties. These have been important and useful in the design of many buildings, but the reality is that once the particular glass is selected and installed, it is a fixed or “static” solution. Static solutions are permanently clear or tinted or reflective regardless of changing seasons or sunlight conditions—and cannot respond to changing conditions. This static trait means that either interior or exterior shading will likely be desired in many cases for separate control. It also means that any one window will likely strive for an average condition or a worst case condition and thus not be able to effectively address the range of conditions associated with heat gain, glare, and damage to materials.

Given the need to keep the benefits of glazing and overcome the limitations of conventional control strategies, a number of emerging technologies have been applied to glazing that provide “dynamic” rather than “static” control options. Simply defined, dynamic glass can respond to changing light conditions by clearing or darkening as light levels change. Some examples include photochromic or thermochromic glass that respond to UV light or heat and tint accordingly. This type of dynamic glazing requires no electricity and has been used most commonly in products like eyeglasses, causing them to darken in bright light and clear in less light.

A different type of dynamic glass is privacy glass. Specifically designed for interior applications, privacy glass generally requires 110 volts of AC electricity and is a laminated glass with organic compounds placed between the layers. In either case the glass is made clear when the electricity is turned on and resorts to its natural obscured state when the power is turned off. Privacy glass is for situations that require total privacy and is not typically for solar control.

The Electrochromic Glazing Breakthrough

The one active dynamic glazing technology specifically designed for building envelope applications is referred to as electrochromic (EC) glazing. This rapidly growing technology uses a series of thin, non-organic ceramic and metallic films deposited onto the surface of glass that are electrically charged to regulate both light and heat through the glass. Unlike SPD or LCD glazing, however, the amount of electricity used is dramatically less, typically at less than 4 volts DC and less than 10 milliamps. Further, the electric charge is only needed to tint the glass, since the natural state of EC glazing is clear. Through variable tint control settings, electrochromic glazing preserves the human benefits of abundant sunlight, views, and connection to the outdoors but without the associated issues and environmental penalties. This makes it one of the most promising forms of dynamic glazing available today for exterior applications.

EC glazing is made from panes of conventional float glass that are sputter coated with ceramic layers of metal oxides. The processes are proprietary to the manufacturers, but are similar to the way low-e glass is produced. In most cases, nanotechnology is used to control layers to a very fine degree. The total thickness of all the layers of an electrochromic coating is commonly less than 1/50th of the thickness of a human hair. When an electronic voltage is applied across the coatings, ions travel between layers, 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.

The coated panes of glass are fabricated into insulating glass units (IGUs) using another piece of glass (clear, tinted, or laminated) and a stainless steel spacer. These IGUs can be fashioned into windows, skylights, and curtain walls, making advanced electrochromic glazing as easy to specify and install as conventional “static” windows. An electronic control system is integrated with the installed glazing and can be customized depending on the needs of the project. The glazing can be controlled by an automated control system, a Building Management System (BMS), or manually using wall switches, or in various combinations of those methods. Most of the tinting occurs in 7 to 15 minutes, depending on glass size and temperature of the glass. Faster tinting can occur in smaller panes and/or warmer temperatures.

The beauty of the installed system is that since the glass itself is controlling solar light and heat, there is no need for exterior or interior shading or other solar devices to be built, purchased, or installed. Therefore, it integrates easily into any design, and into ordinary construction processes.

Energy Performance of EC Glazing

Using EC glazing means that the glass essentially becomes a “valve” that can be used to meter, regulate, and optimize the use of the solar heat and light coming into the building. It does this by addressing two of the fundamental aspects of all glazing.

EC glazing in its clear state (top image) allows a certain amount of light and solar heat to pass through. With a small electrical current, it changes to tinted (bottom image) and allows notably less heat and light to pass through. Images courtesy of SAGE Electrochromics, Inc.

 

Solar Heat Gain Coefficient (SHGC)

This common glazing characteristic is simply the fraction of total solar radiation admitted through glazing. Expressed as a number between 0 and 1, the lower the SHGC, the less solar heat it transmits and the higher the shading ability.

Visible Light Transmission (VLT)

This similarly common trait is the percentage of the visible spectrum transmitted through a glazing and perceived by the human eye.

SHGC to VLT relationship: Dynamic EC glazing can be tinted from a highly transmitting state to a very dark state to adapt to a wide range of sunlight conditions. By contrast, static glazing (the individual points on the chart) is specific to one condition and cannot be changed. Image courtesy of SAGE Electrochromics, Inc.

Commonly, the higher percentage of VLT in glazing, the higher the value of SHGC, or simply put, more light usually means more heat. Conversely, lower VLT reduces solar heat gain, but it also restricts natural daylighting. When using static glazing, the designer needs to determine the most appropriate values for each of these two characteristics and then they stay that way for the life of the glazing.

With dynamic EC glazing, both of the values are variable and adjustable on demand, meaning that the building can respond to different conditions—relieving the designer from having to select only one set of ideal values. As a practical matter, however, it should be pointed out that the variability is commonly controllable at four pre-set points—a low or dark setting at 2 percent VLT, two intermediate settings at approximately 6 percent and 20 percent VLT, and a high point of approximately 60 percent VLT. These settings preserve the view and connection to the outdoors that humans thrive on no matter the time of day or time of year. By adjusting to outdoor conditions, it reduces glare, discomfort, and fading that negate the human benefits of sunlight. It also optimizes energy use in the building by rejecting solar heat gain when it is not wanted, and allowing it in when it is desirable or acceptable.

Although electrochromic glazing is a unique technological innovation, it is a cost-effective solar control system. Installed projects have been shown to generate dramatic reductions in operating energy costs since the EC glazing effectively blocks or admits solar heat and light as needed, thus reducing energy demand for heating, cooling, and lighting. Adding to the effectiveness, some advanced electrochromic glazing products have SHGC values of 0.09 in a tinted state, which is approximately three times better than most commercial static glazings. Even in this state, the EC glass transmits 2 percent of visible light. EC is also very cost effective, and can be cost neutral when compared to traditional solar control solutions, such as the combination of low-e glass with blinds and sunshades. This improved performance can also reduce first costs related to energy systems in new construction as smaller HVAC systems can often be used.

Reducing heat gain and energy use in a public space with a skylight becomes very manageable using EC glazing, which is shown in its normal clear state (top image) and dynamically tinted (bottom image). Photos courtesy of SAGE Electrochromics, Inc.

 

Regarding the operation of the EC glazing it should be stressed that due to its electronic nature, it uses minimal electricity. To put things in context, 2,000 square feet of EC glazing (approximately 100 windows) has been shown to be controllable using less power per day than one 60-watt light bulb. Hence, in exchange for a very minimal energy use, much more energy use can be offset and large potential net savings realized. Photovoltaic (PV) solar cells could also be a source of that energy. Because of their low DC voltage and power consumption, and the complementary relationship between the amount of sunlight available and the level of tinting required, EC glazing is an excellent candidate for PV power.

The overall energy results of a properly installed EC glazing system installed in a typical building are realized in several ways. First, it has been demonstrated to reduce overall energy loads (heating, cooling, and lighting) by up to 20 percent by controlling the daylight and solar heat gains of a building. The U.S. Department of Energy (DOE) is even more optimistic in its estimate that electronically tintable window systems are capable of providing up to 40 percent savings on energy bills and 20 percent on operating costs. Secondly, EC glazing can have a ripple effect by lowering peak electrical demand power requirements by up to 30 percent, saving some building owners a considerable amount of money beyond pure consumption costs. Thirdly, when used as part of an effective overall daylighting strategy, it can lower electrical lighting costs by up to 60 percent. Finally, all of those load reductions conclude that EC glazing can reduce HVAC equipment sizing by up to 25 percent compared to conventional building designs.

Looking at the bigger picture of energy consumption and CO2 emissions, utility companies commonly run their most efficient power plants to meet base load demand and slowly bring on less efficient, more CO2 emitting plants as demand increases. The increased electricity demands are most common during hot weather periods with abundant sunshine. Electrochromic glazing reduces the building loads during these peak utility times, thus directly contributing to reducing power plant emissions. In full building installations, electrochromic glazing can reduce peak load carbon emissions by as much as 35 percent in new construction and 50 percent in renovation projects.

Sustainability Factors:Living with EC Glazing

In addition to energy savings through solar heat gain management, electrochromic glazing contributes to an energy-efficient, sustainable building in several other important ways as discussed further.

The comfort and ambience of this restaurant space with EC glazing can be more desirable than rooms with adjustable interior blinds. Photo courtesy of SAGE Electrochromics, Inc.

Comfort Through Glare Control

The qualities that make EC glazing sustainable also contribute to the comfort and performance of the building's occupants. In human factors evaluations conducted by the Lawrence Berkeley National Laboratory (LBNL), people greatly preferred to be in a room with electrochromic windows versus a room with regular static glass and blinds, because of the level of comfort it brought to the space. This supports what we have already established, namely that controlling glare improves occupant comfort and productivity. But equally important, when glare is removed, occupants can see without closing blinds or shades. With static glass, the only way for an occupant to control glare is to pull the shade or blinds. Most shades are controlled manually but even in automated systems, glare often forces occupants to override the system and close them. So blinds or shades are closed when glare is present, but rarely reopened at the optimized time for energy efficiency. This unhappy situation negates the benefits of the window and decreases the effectiveness of any daylighting strategy. The penalty of glare discomfort is that electric lights get turned on that might otherwise have been kept off.

By using dynamic EC glazing, windows can be dimmed down to 2 percent VLT eliminating glare without blocking the view outdoors. By comparison, static windows in commercial buildings typically transmit around 45 percent visible light, thus the need for shading. When glare is removed, occupants can see their computer, tablet, phone, TV screens, or the view out their window without the need for closing blinds or shades.

Material Protection

Many materials are damaged by too much exposure to the sun, primarily through fading or degradation. Ultraviolet (UV) light is the primary culprit that causes fading so most glass manufacturers measure UV transmittance only. But even glass that claims 98 percent UV protection covers only the 300 – 380nm wavelength range. That still admits sizeable amounts of damaging radiation in the visible spectrum. The most advanced dynamic electrochromic glazing blocks nearly 100 percent of UV but it also blocks 97 to 98 percent of the total radiation spectrum that can cause fading damage to furniture, artwork, carpet and other materials. Controlling solar radiation eliminates the embedded costs of fading including the manufacturing, transporting, maintaining, replacing and disposing of large amounts of interior materials that are otherwise damaged.

Durability

One key measurement of true sustainability is durability. Over a long life cycle durable products save energy and resources required to manufacture, transport, maintain and dispose of products that otherwise need frequent replacement. Increasing the durability of windows means that all of these life cycle costs are reduced but the building owner will specifically see the benefits in reduced maintenance and replacements costs. When it comes to using EC glazing in the windows, the inorganic, all-ceramic structure of the electrochromic coatings provides a superior level of durability. In particular, they perform quite well against highly stressful environmental conditions, such as sunlight, UV exposure, and temperature, experienced by an exterior window product.

Based on the nature of the glass and the coatings, it would be expected that in the static condition, EC glazing would perform well in terms of durability. However, in the dynamic condition, it has also been shown to perform exceptionally well. Since the glazing is electronically switched to create the tinting, it is reasonable to ask how durable the product is when cycling through that switching. Toward that end, ASTM Test Standard E-2141-06 has been used by the National Renewable Energy Laboratory (NREL) to address this very question. NREL conducted the test which looked at the combined degraded effects of elevated temperature, solar radiation and extended electrical cycling. The test results showed that EC glass windows “… successfully survived over 100,000 cycles …equivalent to switching a window 9 times per day for 365 days per year across a 30-year lifetime.” This is an impressive testimony to the durability of the technology, particularly when compared to an average service life of approximately 7 to 10 years for interior blinds and shades.

So what happens if a pane of electrochromic glass gets broken? EC IGUs are easily replaceable. If the glass gets broken, it can be deglazed like any ordinary glass unit, and simply unplugged. A new IGU can be installed and reconnected to the low-voltage wiring, which resides in the glazing pocket.

LEED® Contributions

Electrochromic glazing conserves energy, and also provides an additional tool for sustainable daylighting design. The most advanced electrochromic glazing products can contribute to a number of potential LEED points including:

• Energy & Atmosphere Prerequisite 2 and Credit 1 – Optimize energy Performance: As we have seen the use of EC glazing has been shown to reduce energy demand in various ways including heating, cooling, and lighting energy. In preparing energy models to demonstrate these capabilities, the proper SHGC and VLT parameters will need to be input based on the optimal settings for the glazing.

• Indoor Environmental Quality Credit 6 – Controllability: Windows and skylights with EC glazing are programmable and can be set to operate individually or in zones, by single users or for multi-occupant spaces to meet group needs.

Among the LEED contributions that EC glazing can make, controllability of the glazing to effect comfort is readily achievable. Photos courtesy of SAGE Electrochromics, Inc.

 

• Indoor Environmental Quality Credit 7 – Thermal Comfort: EC glazing can be tinted to stop solar heat gain without blocking the view. In winter, the glazing can be kept in its high transmission state when maximum solar light and heat are desired, and the low-emissivity electrochromic coating helps keep the heat inside the building. In summer, it can reject the unwanted heat to help keep the interior cooler.

• Indoor Environmental Quality Credit 8 – Daylight & Views: The beauty of EC glazing is that the sun's energy can be controlled without blocking the view. EC glazing is always transparent, even in its darkest state, so people can always see through the glass. In an evaluation carried out by the Department of Energy, people greatly preferred to be in a room with EC glazed windows over one with static, low-e windows.

• Sustainable Sites Credit 8 – Light Pollution: When in their tinted state which can transmit as little as 3.5 percent visible light during the night, EC glazing dramati-cally reduces light trespass.

• Innovation in Design Credit 1 – Innovation in Design: The innovative nature of EC glazing is ripe for applying it in ways to qualify for this credit.

Clearly, EC glazing can play an important role in LEED certified buildings as an integral part of the larger sustainability design and strategies.

Specifyng and Designing with EC Glazing: Design with Light

There are two key design factors that are unique to electrochromic glazing and can be used in almost unlimited ways to maximize performance and comfort namely, control strategies, and zoning of the glazing. Each of these design factors are discussed in further detail below.

Design Control Strategies

Control strategies determine when the glazing will be in its darkened, clear or intermediate state. They include daylight control, schedule control, and glare control. Each can be addressed individually or they can be combined into an overall strategy.

The specific mechanisms of control can be manually based or automatic by using a daylight sensor, occupancy sensor, or sensors tied into a control system. Depending on the sky conditions (cloudy vs. clear), and sun position, the control system using photo sensor inputs can control tint level to achieve the optimum foot-candle level. With overcast skies, the glass may be cleared to admit enough daylight to achieve optimum illumination within the space. With clear skies, the control system can darken or partially tint the IGUs to limit daylight to obtain the same foot-candle target, while concurrently reducing solar gain. By using multiple sensors in multiple locations, the tint level can be linked directly to the amount of daylight or solar gain desired in any particular space. The control system calculates the angle of the sun based on the time of year (or day) and photo sensor inputs allow for the system to optimize the daylight and amount of solar energy desired in the space. Daylighting controls based on seasonal variation can block solar gain in summer to reduce air conditioning loads, or allow more solar gain in winter to reduce heating needs.

Glare control strategies will play directly into the overall tinting control strategy. Tinting the glass fully (to 2 percent VLT or less) will achieve occupant comfort in direct sunlight or intense reflected light. It is important to note that all individual window panes do not need to be reduced to that level. Rather, the user can also control the glazing through zone control strategies which allow groups or “zones” of windows to be tinted while others can be clear. This is possible because windows and skylights with electrochromic glazing are highly programmable down to each individual pane of glass.

Zones can be established in different bands of window panes to provide the appropriate degree of glare and solar control with EC glazing. Photos courtesy of SAGE Electrochromics, Inc.

 

For example, since the sun's glare is directional, EC glazing can be programmed to “track” the sun as it moves around the building. With more zones come a greater number of opportunities to optimize and balance glare, daylighting and energy issues. Alternatively, individual rooms or spaces can be zoned to allow horizontal rows of glazing to respond together such that an upper or lower row(s) can be tinted to block glare where needed while other rows can be left clear.

Specifying EC Glazing

When specifying electrochromic glazing in building projects, there are several things to take into consideration. The process is very analogous to specifying other types of insulated glazing and will be part of the appropriate glazing specification for a project. When it comes to the specification addressing EC control systems, that portion is analogous to specifying control systems for automated blinds. In essence, the specifications for an EC glazing system and associated controls are all very similar in concept and process to other conventional systems.

Electrochromic glazing is available in a range of colors that can coordinate with glazing elsewhere on the building. Photos courtesy of SAGE Electrochromics, Inc.

• Quality Control: Since EC glazing is typically made into insulated glazing units (IGUs), ASTM E2190 standard for IGU performance is a minimal quality standard. After that, ASTM 2141-06 Standard for electrochromic coatings on IGUs is an obvious requirement as well. In addition, specifying products that come from manufacturers that carry IGMA & IGCC certifications will be worthwhile.

• Submittals: Some submittals can be requested during the design review stage of a project or they can be reviewed during construction. Common submittals might include:

• Modeling of glass performance

• Glazing design, zoning layout and control documentation

• Technical coordination for control system and wiring

• On-site mock-ups

• Coordination – The EC glazing will require low voltage electrical input and control connections, therefore the work of the EC glazing section will need to be coordinated with the work of those sections and vice versa.

• Products: As with all glazing, there are options and choices among manufactured products. Perhaps the most significant will be the choice of double- or triple-pane insulated EC glazing since that will affect frame sizes and detailing in addition to energy performance. It is also possible to use various shapes and sizes of EC glazing. Essentially any rectilinear or triangular shape is possible; however, circles and arcs are not currently available. Finally, just like other glazing, there are choices in glass and tint colors including grays, blues, and greens. This allows ready coordination with other glass tint colors in the building that may not be electrochromic.

• Installation: Using an experienced installer is important for proper installation of the EC glazing and control system. It is also possible to request that the EC glazing be part of a building envelope commissioning process.

• Maintenance: On-site support for training building management staff is important so that it is programmed and used as intended. Otherwise, maintenance and cleaning will be the same as other insulated glass units.

Case Study: Kimmel Center for the Performing Arts

Photo courtesy of SAGE Electrochromics, Inc. PROJECT: Hamilton Garden Terrace at the Kimmel Center, Philadelphia, Pennsylvania ARCHITECT: BLT Architects, Philadelphia, Pennsylvania GLAZING CONTRACTOR: APG International, Glassboro, New Jersey The Challenge The Kimmel Center in Philadelphia, Pennsylvania, is a city-block-wide collection of performance halls and open spaces enclosed inside a soaring, 150-foot-high barrel-vaulted glass roof. At the Center’s highest elevation sits the Dorrance H. Hamilton Garden Terrace, which offers stunning views of the city and overlooks the entire Kimmel Center complex. Unfortunately, the barrel-vault roof also created two problems that limited the terrace’s appeal. It made the space too hot to occupy during the day, and it reflected noise from events, interrupting other guests below. The Solution To solve these challenges and make the garden terrace altogether more hospitable, the building’s owner turned to a local architectural firm, BLT Architects. The firm explored several options for controlling the heat in the garden terrace, but none provided the right mix of capabilities. “We initially designed in motorized shades that would be pulled during the hot times of the day because we knew the solar load would be so intense,” said Donna Lisle, an architect on the garden terrace team. “But motorized shades are expensive, often break or won’t close evenly, and you can’t see out through them. The glazing contractor, APG International, Inc., suggested we look at electrochromic glazing as an alternative, which has worked out perfectly for the project.” At the Kimmel Center, the EC glazing helped transform the Hamilton Garden Terrace into an elegant glass and steel structure that does not have the original space’s noise and temperature problems. A new glass enclosure limits event sound propagation, and a 2,100-square-foot rooftop made from EC glazing lets the building’s owners maintain a comfortable temperature for occupants without obstructing the space’s breathtaking views of the city. Benefits Edward Zaucha is CEO of APG International, the glazing contractor who installed all of the glass in the garden terrace roof. “With its barrel roof and extraordinary amount of daylight, the Hamilton Garden Terrace presented us with some interesting glazing challenges,” Zaucha said. “For solar control, electrochromic glazing delivered a solution that no other glazing could provide.” Architect Lisle added that the EC Glazing helped her firm deliver a “wow factor” that the building owner very much wanted in the new design. “When the EC skylights fully tint, they create this big defined square of clear cobalt blue that is stunning to view from the plaza below or outside from the street,” Lisle said. “The building owner also wanted the design to enhance the rental appeal of the terrace as a ‘sky room’ which was characterized by its connection to the day and night sky and the unique perspective of seeing the cityscape from above. Being able to maintain those views with EC glass helped us achieve those objectives.”

 

Conclusion

Dynamically controllable electrochromic glazing has emerged as a real and viable option for buildings of all types particularly those seeking to be sustainable. Properly used and designed into buildings, it has been shown to significantly improve building energy performance and reduce peak electrical demand, while also reducing emissions. It also enhances the human experience in buildings by maintaining views and enhancing daylight while controlling solar heat gain and glare. Overall, it allows windows and the buildings that they are located in to interact directly by responding to both the exterior conditions and the needs of the occupants. This 21st Century technology will likely benefit designers, building owners, and building occupants for years to come.

Peter J. Arsenault, FAIA, NCARB, LEED AP, is a nationally known architect, sustainability consultant, technical writer, and continuing education presenter. www.linkedin.com/in/pjaarch

SageGlass®, a product of Saint-Gobain, is advanced dynamic glass that can be electronically tinted or cleared to optimize daylight and improve the human experience in buildings. With SageGlass you can control sunlight and glare without shades or blinds while maintaining the view and connection to the outdoors. SageGlass is manufactured in Faribault, MN, in the heart of the “Silicon Valley of the window industry,” and is a wholly owned subsidiary of Saint-Gobain of Paris, the world's largest building materials company. www.sageglass.com