Dynamic Glass Shines In Sun Or Shade

Dynamic Glass Shines In Sun Or Shade Smart glass is clean, green, and energy effi cient while providing design options.

Lou Podbelski, Sage Electrochromics Inc.

Everyone loves glass, and architects go to great lengths to maximize its use. Glass creates sleek facades. It gives building occupants an offi ce, patient bed, or classroom with a view. It delivers abundant natural light that makes occupants happier, healthier, smarter, and more productive. That light also generates free heat in the winter and saves money on artifi cial lighting. After we design in all that wonderful glass, what do we do? We turn around and cover it back up. We choke off the natural light with expensive solar controls to minimize heat gain and glare. We install mechanized shades, blinds, and awnings. We put architectural fi ns or louvers on the exteriors of buildings. While these appurtenances do their job— reducing solar heat gain in a building—they are expensive to install and maintain. They hamper glass cleaning. And, considering all the materials, transportation, and operational energy they consume, they needlessly expand a building’s carbon footprint. That’s a real concern for architects, contractors, and building owners striving for a truly sustainable building. Another method of reducing solar heat gain is to permanently tint the glass, which blocks the sun and, consequently, the view. Either way,

What appears to be a source of potential daylighting overkill—a full wall of windows—actually comprises dynamic, or smart, glass, which can be tinted at the touch of a switch or even automatically.

the building has lost the light it was designed to embrace, defeating the purpose of the windows.

Another way

Fortunately, new technology gives us another way. Dynamic glass or, by its more technical name, electrochromic glazing, is the latest and perhaps most dramatic advance in daylighting in recent years. It fi nally lets us live in harmony with light.

Dynamic glass lets natural light pour in when it’s wanted. When it gets to be too much, the glass dynamically changes its tint. It works with the touch of button, or, when tied to a building’s energy-management or automation system, activates automatically in response to environmental conditions. While it blocks out glare and keeps things comfortable, occupants stay connected to the outdoors because the glass always remains transparent.

A dynamic solar-control solution, such as SageGlass from Sage Electrochromics Inc., Faribault, MN, offers numerous advantages over traditional options, such as standard, static glass with solar control add-ons and windowless monolithic walls. Prior to its invention, there was no practical, energy-effi cient way for architects to provide natural daylight and an outdoor view, while simultaneously controlling glare and solar heat gain.

Let the sun shine in

Daylighting is a fancy word for letting natural light into a building. Many studies show that daylighting and outdoor views improve worker productivity, job satisfaction, and employee retention. Patients in healthcare facilities heal faster, need less medication, and have morepositive outlooks. In schools, natural daylight and views have been shown to signifi cantly improve student performance, health, and overall attitude.

With this in mind, architect Ryan Benson of

A series of photos illustrates the changes in electrochromic glass as required by available light: clear glass to permit maximum natural light into the space; slightly tinted to allow adequate light without accompanying solar heat gain; and fully tinted glass to keep solar heat completely out of the space.

Schmidt Associates Inc., Indianapolis, designed a beautiful glass ridge-roof pavilion for Ball State University in Muncie, IN. “Students perform better with daylighting and views,” Benson said. “[Electrochromic glass] was the best option because it enabled us to maximize natural light and a view to the outdoors while creating a space that’s thermally and visually comfortable for the students inside.”

Gary Canaday, Ball State’s manager of campus construction, facilities planning, and management, agreed. “We looked at installing mechanized shades and blinds, but that option was not attractive and would have created ongoing maintenance issues.”

Dynamic glass lets glass-façade designs remain uncluttered. Architects need not limit their designs with glass, nor do occupants need to crane their necks or take a walk to look outside. Owners can save some money on energy, maintenance, and resale value.

More window, less wall

Buildings are among the country’s greatest energy liabilities, annually consuming nearly 40% of our total energy and emitting 38% of the CO 2 . Traditional façade solutions contribute heavily to poor performance by letting in too much heat on hot days and too much cool air on cold days, increasing the demand on HVAC systems and driving up energy costs—typically 30% of a building’s operating costs.

As a result, building codes are looking for fewer windows and more wall. For example, the 2012 International Energy Conservation Code aims to increase energy savings in buildings by reducing the window-to-wall ratio to just 30% (a 25% reduction over the previous level of 40%.) Although the glass industry has made advances in improving the thermal effi ciency of windows with technologies such as triple-pane low-e glass, they still suffer from the traditional sun-control problems.

Dynamic glass offers a solution. By carefully modulating heat gain but possessing the newest insulating properties, dynamic glass reduces the required size and cost of HVAC systems needed for a building. It also eliminates the need for add-on solar controls. Architects can put windows where they want them and improve energy effi ciency.

Combining dimmable lighting controls with an appropriate amount of dynamic glass in the correct location in a building envelope can save energy across different climate zones. This energy-savings potential far outweighs the incremental benefi t of reducing U-factor or the solar heat-gain coeffi cient of conventional glass, or even reducing the window-to-wall ratio.

Dane Gillaspie, a research scientist at the National Renewable Energy Laboratory, Golden, CO, said that widespread use of smart-window technologies “could save about one-eighth of all the energy used by buildings in the U.S. every year, equivalent to about 5% of the nation’s total energy budget.”

Integration and planning

Daylighting, aesthetics, and energy effi ciency are three big reasons dynamic glass is changing the way buildings are built. A standard panel-mounted control system lets dynamic glass integrate seamlessly into smart building-control systems to manage natural light right along with electric lights, HVAC, security, and other systems.

Dynamic glass is fabricated into industrystandard insulating-glass units (IGUs), then installed into frames supplied by the manufacturer’s window, skylight, and curtain-wall partners, or by a supplier chosen by the architect or builder.

To reap maximum benefi ts, designers and architects should integrate dynamic glass into their buildings at the beginning of the design phase. Good daylighting requires the synthesis of lighting, envelope, and interior planning. To take best advantage of natural light, the right amount of glass must be in the correct locations in the optimum interior layout.

From a specifi cation standpoint, key aspects of the overall building-design process need to be integrated into a holistic specifi cation approach. The lighting design ideally should be specifi ed as part of the envelope or the interior.

Done right, dynamic glass makes good sense from business, aesthetic, human, and environmental standpoints. The light at the end of the tunnel is beautiful, well-lit buildings for all occupants to enjoy.

Lou Podbelski is vice president of architectural solutions at Sage Electrochromics Inc., Faribault, MN.

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