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Word for Word
Architects Talk about Glazing Trends, Benefits and Why they Opt for Glass
by Ellen Rogers

When it comes to glass, building designs and trends have changed a lot in the past three decades. In the 1980s it was all about the shiny, highly reflective glass box that rendered a low visible light transmittance and low solar heat gain coefficient. By the 1990s, low-E coatings began making their way into the market and energy code changes called for better performance.
Today, with the accelerating drive toward going green and meeting Leadership in Energy and Environmental Design (LEED) requirements, more and more designs call for daylighting, higher visible light and more transparency.

Without a doubt, the role that glass can play in terms of energy efficiency is one of the biggest reasons for its use. But performance aside, there are a lot of other architectural reasons for using glass. These can range from decorative appeal, colorful options, safety and security.

So just what, specifically, are architects thinking when it comes to glass? This month the Architects’ Guide to Glass & Metal magazine caught up with several architects around the country and asked them to weigh in on glazing trends and why they use glass in their designs. While their reasons varied, common themes included performance and aesthetics.

Paul Sternberg,
CSI, CCS, CCCA, LEED-AP
CSO Architects Inc., Indianapolis

AGG: What glazing features do you find most attractive?
PS: Glass offers the unique ability among architectural products to perform multiple functions through a transparent surface. We use glass to form enclosures, provide views and light, exclude radiant energy, resist structural forces and create an artistic backdrop or screen. Glass is probably the most versatile building material that we use.

AGG: How extensively do you work with glass?
PS: Our designs include a broad range of projects with just as broad of a range of design criteria. Glass use runs from being strictly utilitarian to being a major design feature. Our most significant buildings use glass in some way as a major design element, acting both functionally and aesthetically within the overall design.

AGG: What are some unique projects with which you’ve been involved?
PS: CSO Architects has been involved with a range of such projects. The Palladium at the Center for the Performing Arts in Carmel, Ind., is a 1,600-seat music performance hall, completed in 2010, that includes a movable canopy of glass reflectors over the performance platform. It is the largest such installation in the world. Its four movable sections are used to help tune the hall for various types of music performances. Glass was chosen so the intricate plaster dome work and ornamentation of the hall ceiling would not be obscured. Each section of glass is laminated and varies in size, shape and thickness to maximize sound dispersion. Where similar halls use reflecting clouds of solid materials for the same purpose, glass is used to achieve the required acoustical performance without obscuring the classical architectural features of the hall.

The Indianapolis Airport Terminal, completed in 2008, was the first all new airport terminal designed after 9/11. As such, it incorporates new paradigms for the security operations of the terminal. Despite security concerns, design architects HOK made glass the centerpiece of the design. With its expansive curtainwall front and 100-foot diameter cable-supported central skylight, security appears to be the least important criteria of the design. The glass envelope is designed to withstand specific blast threats and the building is also seeking LEED certification, proving that lightness, security and energy performance can all be obtained with a glass envelope. 

The New Commons in Columbus, Ind., is a replacement of the signature design by Cesar Pelli that acted as the gateway to Columbus architecture for thousands of visitors. The original, planar dark glass design was replaced with a faceted, high-performance clear glass design utilizing the original building frame as homage to Pelli’s work. The change in transparency and articulation of the glass wall makes it a more inviting, human-scaled building that expresses the celebratory nature of the revived facility.

AGG: What are some reasons for using glass architecturally?
PS: People thrive in natural light. We like views. We like controlled sunlight. We tend to respond favorably to the decorative affects we can achieve with glass. Glass emphasizes our humanity, since our views through it make us relate in scale to whatever we see. Through it we can extend ourselves into the landscape (or urbanscape). Reflection can also expand or expose the world around us.

AGG: What are some current glazing trends?
PS: First, increased thermal performance options to maximize building energy performance while increasing visible light transmittance. As thermal performance increases, so will the extent of vision glazing in buildings. Energy conservation codes force us to optimize envelope designs and we are becoming more sophisticated as designers, tuning building envelopes to balance competing criteria. Our glazing choices are improving, from coatings that allow us to get better performance out of standard insulating units to sophisticated multiple-layer insulating units with R-values approaching those of the average wall values of just a few years ago.

Second, we are continuing to see growth in decorative and artistic glass. The number of producers of cast, molded, formed, coated and colored glasses is increasing. We are finding more ways to use these unique and artistic products and to add interest and highlights to our interior spaces. Glass adds sparkle, transparency, color, form and texture in a way unlike any other product.

Third, designers are becoming more confident in using colored glazing and being creative with color. Colored glazing has tended to be monolithic. The wide range of glass colors combined with laminating colors has broadened our ability to make glass a color element in our designs. We will begin to realize the opportunities of using patterns of colored glazing to make more vibrant designs or to mimic the color patterns we achieve with other materials.

Christopher V. Ward,
AIA
CWArchitects, Los Angeles

AGG: What glazing features do you find most attractive?
CW: We use glass in many different applications and for more than just fenestration (i.e. interior walls, partitions, etc.). We can we add color and imagery to the glass to make it more interesting. The great thing about working with glass is you can color it, mold it, support it horizontally and vertically and it is very malleable.

AGG: How extensively do you work with glass?
CW: All of our projects have a distinctive glass element, which has become one of CWA’s signature architectural features. I would say that all of our projects start with the question, what can we do that is different and exciting? And almost always the answer includes using glass as a feature in the design.

AGG: What are some unique projects with which you’ve been involved?
CW: Two elementary schools we did have unique glass elements. One has a glass tree curtainwall and a multi-colored skylight and the other, now being built, will feature a wall with multiple images related to the school’s values and mission statement. Another project now under construction uses glass as a reflective landscape inside a retirement home. And at the Tournament of Roses headquarters in Pasadena, Calif., we created exterior walls completely of glass, so people in their offices will feel as though they are working in the gardens.

AGG: What are some reasons for using glass architecturally?
CW: Glass gives you a lot of bang for the buck and is a material that people understand easily. By using glass and manipulating the color, shape and form people can still comprehend it, even though the technological advances [used to create it] may be very difficult to understand. Another great reason to use glass is that philosophically it almost always denotes fenestration, or an opening to the outside. Even though you have a completely interior space, by using glass as a medium for supporting an image in a large expanse, you can create the sense of outdoor space where none existed before.

AGG: What are some current glazing trends?
CW: We are imposing imagery on glass and using multi-colored glass in curtainwalls to create interest. Also, we are starting to use it structurally for interior dividers, incorporating it with varying opacities more and more.

Craig McIlhenny,
AIA
Ennead Architects, New York City

AGG: What glazing features do you find most attractive?
CM: Architectural glazing options, particularly for façades, are increasingly complex. Current glazing technologies provide a wide range of design and performance characteristics that allow architects to balance aesthetic intent, building orientation, solar and thermal loads and occupant comfort. Features such as low-E coatings, which have been around for some time, are nearly ubiquitous for any building that incorporates significant areas of glass. Coating technology has advanced dramatically over the last ten years to provide improved solar performance while simultaneously becoming more neutral in transmitted color. Ceramic frit technology, while also not new, is now more prevalent than ever, with many buildings utilizing 30- to 60-percent coverage patterns to shade the building and reduce load on the building’s AC systems. Frit patterns are nearly limitless in design, and some glass fabricators offer a dual-color application, with one color facing outward and another into the building, allowing glare issues to be addressed. Insulating glass units are an obvious choice for all façades. However, triple-glazed units can be substantiated if project budgets allow and payback can also be
substantiated. 

AGG: How extensively do you work with glass?
CM: Many of our projects include extensive areas of glazing, depending on the program and siting—anywhere from 20- to 50-percent glazing is not uncommon. This statistic is somewhat meaningless, though, given that a large building can include a tremendous amount of glass even though the overall area of glass as a percentage of the entire building enclosure may be small. Percentage of glazing is increasingly driven by energy-code requirements. Codes require minimum performance values of glazing, including shading coefficients (solar gain) and U-values (thermal loss).

AGG:What are some unique projects with which you’ve been involved?
CM: The Weill Cornell Medical College’s Weill Greenberg Center incorporates white ceramic fritted glass and low-iron glass to create a monolithic white glass building that softens the natural light to the interiors. In addition, the college’s Medical Research Building features a double skin, all-glass façade, which includes an inner wall of low-E coated insulating glass, and an outer wall of laminated, double-fritted (black and white) glass that functions as a parallel sunshade. 
The Westchester Community College Gateway Center project in Valhalla, N.Y., utilizes low-iron, double-glazed units to create maximum transparency in the building’s entrance atrium. Fritted and low-E coated units are also used to boost performance and shade the atrium space.

AGG:What are some reasons for using glass architecturally?
CM: Among the important elements of our design process is the exploration of new materials and systems. We have been investigating the aesthetic and functional opportunities afforded by glass for well over 20 years. As glass technology has advanced, so too, have our experiments.

In addition, clients are recognizing the powerful impact that glass can provide. Glass façades have an aesthetic appeal to many clients who appreciate an expression of the technology behind it (i.e. large areas of glass and systems to support that glass). And when done well, glass façades can contribute to the establishment of a strong institutional identity as clients seek to recognize and elevate the stature of their intellectual community.

It is interesting to note that clients specifically request that we incorporate glass—and often significant amounts—into our designs. For example, the desire to increase the amount of daylight that penetrates into a building center typically requires that we use increased areas of glass or façade design features that reflect more light inward. Today, I think everyone sees that both architect and client are concerned with building projects that are sustainable. Glass is not a good insulator of buildings, and significant heat loss and heat gain occur through vision glazing. This has a big impact on energy use, and many times daylighting decisions are driven by sustainable or LEED goals. That being said, glazing and curtainwall fabrication technologies are constantly improving—with better performing low-E coatings to reduce heat gain and better curtainwall framing systems that reduce heat loss. With a well-designed curtainwall unit frame utilizing triple-glazed and low-E coated glass, U-values can be significantly better than those of a standard dual-glazed unit that simply meets code.

AGG: What are some current glazing trends?
CM: The glazing industry is currently pre-occupied with thermal performance. Many solutions are currently available that address thermal loads such as photovoltaic glazing units, spandrel units that capture solar heat and redistribute it to the building mechanical systems, double façades, and low-E coatings that reject more and more solar load away from the building interior. There are also many developments in other areas such as laminated films, which offer a wide variety of color choices; glass coating technologies that address radio frequency issues such as cell phone signal strength; and structural innovations allowing nearly all-glass construction for applications such as stairs and other load-bearing elements.

Ellen Rogers is the editor of the Architects’ Guide to Glass & Metal magazine.

Architects' Guide to Glass & Metal
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