Today, more and more architects are literally thinking outside the box. Modern buildings are taking on unique shapes and forms, and structures are reaching staggering new heights. This shift means the purpose of the building envelope is also expanding.
One of the strategies employed by architects to increase (or regain lost) glazing area to meet the performance objectives of building energy codes and standards involves using established building envelope elements such as window louvres, fins, and shelves, along with emerging technologies such as vacuum-insulated glazing and panels (VIGs) and electrochromic (EC) glass.
For decades, the words ‘design flexibility’ and ‘fire-rated glass’ would not have appeared in the same sentence. Traditional polished wired glass was the only glazing material permitted in fire-rated areas. Its network of wires holds together broken glass during a fire to slow the spread of flames and smoke longer than was previously possible with other available glazing products.
The building industry consumes 40 per cent of the world’s energy, and is responsible for more than 38 per cent of greenhouse gas (GHG) emissions, according to studies completed by the World Business Council for Sustainable Development (WBCSD 2009). The energy demand and its costs will continue to increase; this explains why Canadian building code requirements are becoming more stringent.
Glazing is an integral part of modern design. From a thermal standpoint, glazing and its structure or frame is the weakest point of a wall assembly.1 A double-glazed vinyl window with argon’s U-factor (i.e. thermal transmittance) is typically around 3 W/(m2 K). This means the window will gain or lose around 3 W per m2 per degree Celsius. An efficient fibreglass window system’s U-factor can be as low as 1 W/(m2 K). An aluminum curtain wall system can range as high as 4 W/(m2 K). On the other hand, the U-factor of a 152-mm (6-in.) steel stud, with batt and exterior continuous insulation, can be around 0.4 W/(m2 K).
When looking at its skyline, it is no wonder why Vancouver is known as the “City of Glass.” Glass high-rise buildings, each one taller than the next, have been the architectural vision developed over many years (Figure 1). In fact, the relationship between West Coast architecture and glazing systems is symbiotic; their evolution would not have been possible without one another.