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 it comes to the energy efficiency of its buildings, Canada is something of a paradox. On one hand, the country has received its fair share of accolades for green initiatives. For example, this author was in France in September for an International Organization for Standardization (ISO) TC205/TC163 joint workshop, and received laurels for coming from the world’s only nation with a holistic building commissioning standard—Canadian Standards Association (CSA) Z320-11, Building Commissioning. On the other hand, the country recently ranked 11 out of 12 on the 2012 American Council for an Energy-efficient Economy (ACEEE) International Energy Efficiency Scorecard.
The last decade of increased awareness and availability of low-water consumption plumbing fixtures and touchless actuators has led to wide industry acceptance. Across the country, building codes have begun to drive even lower water consumption standards. However, as this new low-flow culture takes root, it becomes clear we, as a nation, are not quite there yet.
With the ever-increasing demand for efficiency in new buildings, as well as the retrofitting of existing facilities, exterior sheathing plays an integral role in reducing energy consumption and the associated carbon dioxide (CO2) emissions. (This article deals with insulating, not structural, sheathing). Exterior insulation, continuous across all structural members without thermal bridges (other than fasteners and service openings), is the most thermally effective way to insulate a building. The sheathing’s thickness depends on the climate zone.
Air barriers have been a requirement of the National Building Code of Canada (NBC) for many years, but not all design professionals fully understand what is involved in specifying one. An air barrier may be a material of many functions and the choice of one over another should reflect the needs of the particular project. Historically, the requirements for airtightness have been found under NBC Part 5, “Environmental Separation.”
Is a green building defined by what it looks like? Should it have various ‘sexy’ technologies like solar panels, green roofs, and straw bale insulation? Or does it need to have low off-gassing materials, plentiful daylighting, and native species landscaping?
Instead of defining a green facility by a checklist of technologies, one should define a building by its actual reduced environmental footprint. As the most significant direct impact of structures, energy use should be the most important way they are ultimately judged. Without significant, monitored energy savings, no facility should be called ‘green.’
Building new homes and modernizing existing ones can be expensive. Project budgets are sometimes exceeded with unexpected surprises and elaborate aspirations; upgrades with crown mouldings, hardwood floors, cabinetry, and countertops all increase costs to the project.
Canada’s climate is one of the more diverse on the planet. It varies based on geography, ranging from long, cold winters and sunless days in the Far North to four distinct seasons along the U.S. border, and typically mild winters in the B.C. Lower Mainland. Temperatures can climb to more than 40 C (104 F) in the summer and drop below –50 C (–58 F) in the winter.
Of all the components of a building enclosure, windows can have the greatest impact on energy consumption. This can be disproportionate to the area of the enclosure the windows cover. Therefore, it is important architects and specifiers are aware of the significant impact of windows on the overall building enclosure’s thermal performance when designing, evaluating, and selecting enclosure assemblies for new buildings and retrofit projects.