December 15, 2018
by Michael Tryon
The green building market in Canada is flourishing. Indeed, more than 50 per cent of building owners, architects, and contractors are reporting over 60 per cent of their projects will be green in the coming years, compared to 33 per cent of respondents in 2014, according to a recent study by the Canada Green Building Council (CaGBC). At a time when many are concerned about the environment, going green provides major benefits, including waste reduction and increased energy efficiency as well as cost savings.
Building green depends largely on the careful selection of all sustainable materials. However, identifying green products for creating a unique and pleasing architectural esthetic can be challenging. This is one of the reasons why channel glass features prominently in new structures throughout North America. Its linear, translucent appearance creates a signature esthetic, as seen at the new Fort York Visitor Centre in Toronto.
The contemporary Visitor Centre, completed in 2016, features an advanced channel glass façade. The centre became a finalist in the Mies Crown Hall Americas Prize, representing some of the most distinguished architectural works in the Americas (Founded by the Illinois Institute of Technology [IIT] College of Architecture, the Mies Crown Hall Americas Prize awards the best built work in North and South America). Having defined the centre’s façade, the translucent channel glass played a key role in securing the award nomination.
Channelling sustainability to preserve history
The Fort York Visitor Centre’s architectural team faced the challenge of preserving the historic nature of the site, while developing a contemporary venue for visitors to admire for generations to come.
Considered the birthplace of the city, the original Fort York was built in 1793. The 17-ha (43-acre) national historic landmark is nestled near the shoreline of Lake Ontario in the heart of the city’s downtown. It is the site of the notable Battle of York during the War of 1812, and is home to the largest collection of original buildings from the war.
Kearns Mancini of Toronto and Patkau Architects of Vancouver worked to enhance the appeal of the site while respecting its cultural and archaeological significance. The architects were inspired to build an abstract structure rising from the landscape, symbolically “illuminating” the history of the site.
“The approach to the visitor centre is underneath the Gardiner Expressway, which is a very large and powerful singular architectural statement, forming an almost cathedral space underneath,” said Jonathan Kearns, director of Kearns Mancini Architects. “Rather than competing with this grandiose structure, we conceptualized a subdued, yet distinct building, metaphorically connecting the fortifications and historic tapestry of the fort. We also decided to construct a transitional zone within the proposed building, creating an ascending viewing platform.”
Hundreds of feet of channel glass clad the abstract viewing platform of the visitor centre. The glass features approximately 40 per cent post-consumer recycled content. It is manufactured using 100 per cent renewable electricity and an innovative oxygen-fuelled furnace, significantly lowering carbon dioxide (CO2) emissions below the industry standard.
Channel glass is a sustainable solution going beyond its eco-friendly manufacturing. It provides a robust layer of protection to the building for decades. The durable channel glass envelope reaches continuous vertical spans of up to 6 m (20 ft), and features glass-to-glass corners in a variety of angles. Strategically positioned mid-point wind clips reinforce the glass wall and reduce deflection under high wind loads, eliminating the need for horizontal stack joints (Figure 1).
“The selection of the glass was to give a sense of sculptural quality to the part of the building emerging into the main plain of the site,” said Dan McNeil, project architect with Kearns Mancini Architects.
Shining a light
The channel glass at Fort York’s Visitor Centre features a light-diffusing surface texture. At night, when the façade is illuminated by lighting fixtures attached to the back of the glass system, the texture produces a gentle glow, a subtle “ghostly” esthetic.
According to Kearns, the inspiration for the channel glass façade came through the idea of a projection-type surface to showcase images of the battlefield. When this idea became technically difficult to achieve within the budget the project team looked for an alternate solution. Channel glass was finally employed as it could be back-lit to create a spectral, ghostly feeling at night.
The choice of the luminous back-lit channel glass façade led to project savings of more than $1 million. The estimate for the total upgrade was budgeted at $25 million.
Serving as the fort’s new front door, the visitor centre contains artifacts highlighting the history of the city, as well as educational and research facilities. The linear flow of the space, combined with the chronological organization of its exhibits, provides a kind of “time tunnel” experience. At the end of the tunnel, visitors emerge onto the fort grounds through two expansive channel glass walls.
“As this part of the building evolved from being a ghost screen into a more substantial element, the choice of glass still has that transparency and almost ghostly quality, especially when illuminated at night. It is quite beautiful,” said Kearns.
Channel glass in the United States
Lighting was also a main design focus at the new Museum of the Bible in Washington, D.C. Opened in 2017, the museum showcases rare and fascinating artifacts spanning 3500 years of history, offering visitors an experience of the Bible and its impact on the world. The museum’s lobby arcade is clad in low-iron channel glass in a translucent white ceramic frit, spanning more than 7 m (22 ft) in height.
The main design objective was to reflect light throughout the lobby, top to bottom. Light radiating from the 43-m (140-ft) long light-emitting diode (LED) ceiling the length of the lobby bounces off the polished channel glass surfaces. According to the project’s architects, the effect magnifies the colour and light from the images moving and changing on LED displays throughout the museum’s arcade, thereby transforming the character of the space by creating an immersive experience.
The exterior of the building features textured channel glass. This light-diffusing glass creates a contrast with adjacent clear insulating glass units (IGUs). The design team was able to successfully integrate the two glass types with the glass manufacturer’s assistance by implementing minimal tie-ins (Figure 2).
“The translucent channel glass bridges the old building and the new museum,” said David Greenbaum, FAIA,
SmithGroup lead designer. “The combination of clear and translucent glass is symbolic of the search for clarity and countering moral ambiguity, inherent to the study of the Bible. When compared to the clear windows, the channel glass implies the human struggle to find an ethical and moral path in our daily lives.”
Environmental benefits of channel glass
Channel glass is a naturally sustainable and recyclable material. It is made of abundant raw ingredients such as sand, soda ash, and limestone. Some channel glass manufacturers have created environmental product declarations (EPDs). The internationally standardized evaluation provides full disclosure of the glass’ environmental footprint. It provides natural daylight, energizing interiors, and reducing the need for artificial lighting. Channel glass also controls acoustics and improves the energy efficiency of the building, aiding or assisting occupant wellness. Additionally, channel glass reduces glare and provides noise control, occupant privacy, and visible light transmittance (VLT). Channel glass can achieve VLT of up to 77 per cent, providing diffused daylight, which can be more desirable than clear views. The self-supporting glass with insulation also reaches a high thermal performance target with a U-value 0.19. Unlike a plain 114-mm (4.5-in.) batt-insulated stud wall impervious to light, channel glass can reach a sound-reduction rating of sound transmission class (STC) 43 and outdoor-indoor transmission class (OITC) of 36.
Bird strikes are a real and common hazard of today’s visually stunning, glass-enclosed buildings, and a potentially jarring experience for building occupants. It is estimated more than a billion birds are killed each year due to collisions with glass in built structures.
The enormity of the ecological impact is enough that some municipalities, including Toronto, San Francisco, Oakland, and Palo Alto (California), Highland Park, and parts of Cook County (Illinois), as well as the state of Minnesota, have in recent years mandated or promoted bird-friendly architecture for new construction. Additional regulations aiming to reduce avian fatalities are being considered throughout North America.
The American Bird Conservancy (ABC), the authority on avian-friendly architecture, tested and certified channel glass as bird-friendly. The Bird-Smart certification confirms birds can see the channel glass, helping them avoid collisions.
“Everyone has seen or heard a bird hit a window, but few realize how common it is—adding up to hundreds of millions of birds each year in the United States alone,” said Christine Sheppard, bird collisions campaign manager at ABC. “By working with companies to evaluate their glass products, we are able to proactively reduce future collisions and prevent thousands of avoidable bird fatalities.”
Designing and constructing sustainably with “green” materials continues to remain a growing trend. According to a Dodge Data and Analytics World Green Building Trends Report, the global green building sector doubles every three years. There are more than 93,000 Leadership in Energy and Environmental Design (LEED) projects in 167 countries. Among these, channel glass has made its mark on many, including
For green projects of the future, channel glass presents an opportunity to achieve sustainability in parallel with a striking design esthetic.
Michael Tryon is the general manager of the channel glass division at Bendheim. He has more than 20 years of experience in office interiors and architectural products, as well as 15 years of experience in interior and exterior channel glass wall systems. Tryon is an expert on the production, installation, esthetic requirements, and architectural applications for the 3D, U-shaped channel glass. He can be reached at firstname.lastname@example.org.
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