Transparency

Our practice centers on creating buildings that celebrate the egalitarian values of democracy and engage the public realm with places that are accessible, active, and inviting.

Whether designing a library, a courthouse, a temple, or a classroom building, we have found that transparency is a powerful catalyst for achieving openness and welcome, and for strengthening connections within a community of fellow citizens.

From the outside, transparency strengthens a building’s public role by showcasing interior activity that can energize the adjacent street or urban park and can convey a sense of accessibility to diverse constituents (an especially important attribute for civic buildings).

From the inside, transparency allows interior spaces to define new connections to the outdoors: opening to the immediate landscape or urban setting; opening to daylight and its natural fluctuations (improving energy performance and personal well being); and creating an immersive experience where one feels alive and self-aware.

Inside and outside, transparency can create memorable, uplifting places that gather members of a community in all of their diversity—fundamentally important at a time when our virtual connectedness allows us to be more physically removed from one another.

Through our years of practice and research, we have developed a deep understanding of the particular design decisions and evolving technologies that allow greater precision in achieving real transparency. To achieve real transparency, we say that glass is not enough. We can all think of buildings with tinted glass that are quite opaque.

We have found that achieving perceivable transparency involves seven factors:

• Glass Type (selecting clear, high performance glass);

• Glass Support (maximizing the thinness of aluminum and steel elements supporting glass);

• Structure (de-coupling structural elements from the glass wall);

• Lighting (balancing interior and exterior light levels; e.g. backlighting, daylighting);

• Shading (increasing thermal comfort and minimizing glare with interior or exterior shading);

• Program (organizing the building to have its active uses along the glass wall);

• Mock-ups (verifying the combined visual effects of building elements at full scale).

The Cambridge Public Library uses an all-glass front facade to redefine the public library as an open, flexible, and welcoming place of opportunity. At 40 feet tall by 180 feet long, the glass facade activates a major civic park by featuring continuous and highly populated reading areas on the first and second floor. With its emphasis on using transparency to connect the city park with active interior uses, this new building offers a powerful contrast to the earlier vision of library as retreat, withdrawn from the city.

To ensure the highest degree of transparency, we used double-skin curtain wall technology. This innovative, sustainable enclosure system includes two walls of glass separated by a three foot air space. Within the air space are twelve-inch deep, adjustable, micro-perforated sun shades. These shades trap solar heat before it enters the building interior, allowing the glass to be clear and low-iron (the most transparent that glass can be) To maximize patrons’ thermal comfort along the interior of the glass wall, solar heat within the air space is managed: during the summer, the air space acts as a multi-story flue naturally exhausting heat through open vents top and bottom; during the winter, these vents are closed, trapping heated air which serves as a thermal blanket for the building. For visual comfort, the adjustable shades reflect light onto the ceiling to enhance daylighting and reduce glare.

The construction of the double skin is designed to reinforce transparency. All the steel and aluminum glass supports are designed with minimal profiles. A slender ladder truss supports the double-skin curtain wall elements from within the air space, adding a shimmer that enhances the sense of transparency from the outside. The building’s columns are held back from the exterior wall by 15 feet to maximize the sense of transparency from the interior looking out.

Because this double skin is the first of its particular type in the United States (3-foot multi-story flue with 12-inch adjustable louvers), we conducted significant research, including visits to twelve overseas examples of the double-skin curtain wall in Germany and the United Kingdom, where this technology is well established. From that research, we developed a low maintenance version, well suited for public maintenance budgets.

In a place of justice, transparency can make visible the democratic values of openness, fairness, and due process, and also meet the need for heightened security. This Federal Courthouse achieves transparency at a city scale, using a 100-foot tall by 300-foot long glass facade. This glass wall reveals double-height public circulation areas leading to the building’s courtrooms (two per floor). The courtroom entries become part of the facade, highlighting the accessibility of the judicial system to its citizens. Highly visible as the terminus of a major street and along the river front, the building serves as an inviting beacon for civic life.

For this north-facing facade, transparency begins with the selection of clear, high performance glass. Very large glass sizes set to industry maximums limit the number of aluminum elements in the glass curtain wall. Blast resistant glass (a special requirement of this program) is integrated into the curtain wall. One-hundred-foot-tall stainless-steel-clad columns stand in front of and independent of the sheer glass wall, adding to the facade’s sense of layered transparency. Interior light levels enhance the sense of transparency: extensive daylighting fills the tall, shallow lobby space, accentuated by backlighting from a major interior ‘portal’ (45 feet wide by 100 feet tall) as well as continuous skylights.

For a place of worship, significant transparency in the sanctuary helps create an immersive experience for both individual refection and community engagement. With two 36-foot tall glass walls, this sanctuary is infused with balanced natural light that changes throughout the day. One glass wall opens out to an entry courtyard the same dimensions as the sanctuary, while the other looks through a wood screen towards a forested landscape. From the building’s approach, the sanctuary’s sheer transparency projects this community’s welcoming, egalitarian, and participatory values.

The enclosure of the sanctuary is carefully calibrated to maximize the experience of transparency. The two large glass walls are positioned to illuminate (sidelight) two solid walls, balancing daylight and reducing glare on the inside, while making the interior more visible and thus transparent from the outside.

The curtain wall structure is held off from the glass wall, allowing dappled light to flow between multiple slender vertical elements. Slender perimeter columns every 5 feet, integrated with the curtain wall, replace the more typical large diameter columns. In this way, building structure seems to disappear.

For a place of learning, transparency can create a powerful setting with formal and informal spaces for teaching collaboration, break out, group study, and individual study. At the Harvard Business School, a two-story transparent base for its new Executive Education building brings a decidedly contemporary experience to this Georgian campus. This major glass enclosure [32 feet high by 300 feet long (facing the river) and 32 feet by 80 feet (facing the campus)] opens active uses of the lower two academic floors directly to a new campus quad and to views towards the Charles River.
Greater transparency is achieved by extensive use of double-skin technology.

Like the Cambridge Public Library, this double-skin is a three-foot-deep multi-story flue, with vents top and bottom and with adjustable shades. Its inner construction is considerably lighter than that of the Library, using thin stainless steel cables and struts to support the curtain wall glazing. The cantilevered structure allows building columns to be hidden in solid walls and where exposed, to be treated as ‘ladder’ columns that are themselves ‘see through.’

A large atrium (70 feet wide by 32 feet tall) provides significant backlighting, which balances interior daylighting and enhances the experience of transparency, literally framing views through the building.

At Northeastern University, transparency reinforces a university’s commitment to engaging its host city. The sixteen-story Building H faces Boston’s Museum of Fine Arts and helps anchor the university and its new West Campus to Huntington Avenue and the cultural life of the city.

A 220-foot tall and 110-foot wide north-facing glass wall reveals the building’s mixed-use program to the city, with the College of Computer and Information Science on its lower four floors and student apartments above. Reflecting the Dean’s goal of generating a culture of collaboration, spaces with the best views overlooking the city are dedicated to group meeting and informal gathering, bringing researchers, faculty, and students together.

Transparency is created by the use of a high-performance, unitized curtain wall. Backlighting of protruding bays along both sides heightens transparency in gathering spaces at all sixteen floors, both academic and residential.

This essay was originally published in the firm monograph William Rawn Associates Architects by William Rawn Associates, Architects, Inc.

©The Images Publishing Group Pty Ltd 2014

A full copy of the monograph can be purchased here:

https://www.amazon.com/William-Rawn-Associates-Architects-Inc/dp/1864704705

Photo Credits: Robert Benson Photography, Bruce T Martin Photography, Alan Karchmer