Glass technologies promise to change the way we look at the world
Since glass was first manufactured about 5,000 years ago, glass-manufacturing techniques have evolved considerably. No longer do we look out single-pane, wavy glass windows. Now we look out quadruple-pane, argon gas filled, glazed windows. Today's window glass and glazing technologies would definitely impress our ancestors.
It wasn't until the 13th century, when a technique for making clear glass was developed, and by the Renaissance, that glass usage was common. Plate glass for windows only started to become popular in the 18th century after it was discovered that the grinding and polishing of cast glass produced a superior flat surface. And by 1958, the float glass procedure was developed, where molten glass is floated over molten tin to create high-quality, continuous and uniform sheets of glass.
Although float glass manufacturing is no longer prolific in Canada, this process was the most common method for large-scale glass manufacturing from the 1960s to the 1980s and led to the widespread use of window glass in the modern era.
Since the float glass procedure was developed, industry has seen window glass evolve from single- to double-, triple-, and now quadruple-pane glass. Inert gases, such as argon, have been used to fill the space between two sheets of glass. And myriad glazing applications have been developed to do everything from keeping the heat in or out, and most definitely, keeping the burglars out.
Richard Verdon, president of the Canadian Glass Association, says the glass and window markets in Alberta have progressed in the last few years, specifically with the Leadership in Energy and Environmental Design and green building programs. "A quick look at the European glass and window markets tells us there is much room for improvement in our markets," he says. "We still have a lot to learn with regard to constructing energy efficient and sustainable buildings."
The different compositions of glass and varying types of glazing applications allow manufacturers to create many characteristics of window glass such as colour, reflectivity, transparency, strength, thermal conductivity and heat resistance.
Verdon says the industry has seen tremendous improvements in energy models in the last few years that recommend new building technologies with new advanced glazing systems. "The products are out there to construct very good building envelopes," he says. "However, it's usually a question of budgets, and the owners of the buildings control the products that will fit these designs." Some of those new products include glass-clad polycarbonate, building-integrated photovoltaics and electrochromic glass.
Marketed as security glass and known for its strength, glass-clad polycarbonate is made from a layer of tempered glass, a vinyl interlayer, a sheet of polycarbonate, another vinyl interlayer and another sheet of tempered glass. Examples of glass-clad polycarbonate used as security glass include inmate detention areas, interview rooms, psychiatric wards and banks.
The process used to make security glass is also used to make bulletproof glass by adding more polycarbonate layers. Paul Heyens, chief executive officer of Alberta Glass Company Inc., says: "Bulletproof glass only makes up a small part of the window glass in use today. However, it's gaining popularity, especially in buildings that require bulletproof glass due to threats of terrorism. Most new embassies and public buildings in the U.S. use bulletproof glass."
Building integrated photovoltaics, or solar cell technology, already popular in Europe, is slowing entering the North American market. The technology can be incorporated into building envelopes that are used to capture the sun's rays, giving building owners the opportunity to generate their own electricity and even feed electricity back to the grid.
Clear technology is still in its infancy, and until the technology achieves the architectural look and its cost is not prohibitive, it might be a while before we see this technology go mainstream," say Richard Neal, president of the Provincial Glaziers Association of Alberta.
David Langton, a partner at Competition Glass, says, "As energy costs continue to rise, alternate sources need to be looked at, especially solar, and [building integrated photovoltaics] definitely fits the bill."
Glassonweb.com describes electrochromic glass, or "smart" glass, as an energy-saving component for buildings that can change color on command. It works by passing low-voltage electrical charges across a microscopically thin coating on the glass surface, activating an electrochromic layer that changes colour from clear to dark. The electric current can be activated manually or by sensors that react to light intensity. Glass darkening reduces solar transmission into the building. When there is little sunlight, the glass brightens, so that the need for the artificial light is minimized.
Bill Coady, architectural sales manager-Northwest Region of Guardian Industries Corp., says the challenge today is to push the technology envelope for the future while creating a built environment that uses currently available products that are commercially viable, practical and cost effective.
"It's great to incorporate many of the new window glass and glazing technologies into new buildings," he says, "but the reality is that some of these technologies are still relatively new and are just starting to enter the market now. It will take time for these new technologies to become more widely available and more affordable for building owners to incorporate into their building envelope."
For now, Coady says what is most important is that industry incorporate the wisest use of all technologies-not just glass, but architectural, HVAC (heating, ventilation and air conditioning) and environmental technologies as well-into the planning and design of buildings. "Much can be achieved by installing the most appropriate type of glass in different places in a building to achieve better management of heat gain and heat loss. As well, fixed blinds and automatic shades should be considered as variable options to enhance the function of the building."
Downtown Calgary has given industry an opportunity to install new window glass and glazing technologies.
Alberta Glass, western Canada's leading glass and glazing service contractor, was the primary glass contractor for The Bow and Eighth Avenue Place. The Bow, which uses 900,000 square feet of glass-enough to cover 10 football fields-is one example where glass is more than an aesthetic feature.
"For The Bow, we installed Type 2 and Type 3 windows manufactured by Sota Glazing Inc. from Brampton, Ont.," Heyens says. "These windows were installed in the inside curve, faceted walls that are three to 11 metres apart. They were designed and positioned to harvest and control the most intense solar gain (southwest facing). Through the use of blinds on the windows, the operable vents and air movement between the two faces of glazing, the building will control heat and cooling, and minimize the use of HVAC systems while allowing fresh air into the workspaces."