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Fenestration Forum: February 2012

Scientists agree the earth’s climate is getting warmer.

Scientists agree the earth’s climate is getting warmer. Engineers Canada believes we are seeing the early signs of climate change on new and existing buildings.

Premature deterioration because of the stress caused by changes in the weather pattern is a serious concern and is quickly becoming the focus of a great deal of attention in many regions of Canada because any significant change in weather patterns will require modifications to the manner in which we design and construct buildings.

To meet the challenge Engineers Canada has established a Vulnerability Committee to examine the impact on our buildings and infrastructure. You can see their reports and other information online at www.pievc.ca .

The committee defines climate change as being any systematic change in climate elements sustained over several decades. The building envelope serves an important function as an environmental separator and is particularly vulnerable to even minor changes in climactic conditions because these systems have become thinner and lighter as construction technology has evolved. Fenestration components are also in direct contact with the elements.

In existing buildings, the age of the structure, materials used in its construction and the type of building envelope system can influence its ability to resist climate change. For example a 50-year-old masonry building constructed using a face-sealed cladding system has very little capacity to resist the impact because the shell of the building is directly exposed to the ever-changing exterior environmental conditions. In buildings that incorporate pressure-equalized rainscreen walls the environmental separation is concealed and is not generally exposed to the elements.

Several environmental factors can impact fenestration components. Shifts in the form, pattern, and intensity of precipitation, including the frequency of instances of freeze/thaw cycling, melting permafrost, freezing rain and rain on snow can alter the expected lifespan of fenestration, or affect its performance during that span. Shifts in the frequency of high humidity levels, changes in seasonal temperature ranges and longevity of heat waves or cold snaps, and increased intensity of wind and flooding events can also play an important role. These changes acting on an enclosure system can lead to dimensional changes in the materials which can lead to cracking and fissuring in polymer-based materials such as window frames, sealants and gaskets.

Any increase in dust, particulate matter, smoke and acid rain can also have significant implications for fenestration components. In addition, UV radiation, wind-driven dust and rain contribute to accelerated deterioration

These sources of degradation can lead to the following impacts on building performance and longevity: increased health and safety risks for occupants, overall premature or accelerated deterioration, reduced service life and functionality of components, increased risk of catastrophic failure, increased repair, maintenance and energy costs, increases in service disruptions and increased liability.

It is a relatively straightforward building science exercise to simulate at least some of the impacts of various climate change scenarios on full-scale mock-up building envelope assemblies in laboratory settings. Computer simulations might also prove useful. These strategies might assist in to determining what changes in design and building codes could mitigate the impact for new and existing buildings.

Given the size and importance of our building stock it is important we continue to monitor the issue and it is apparent we also need to substantially increase the general attention given to the topic. Climate change will present a challenge for the people who deal with these components of modern buildings: architects, engineers, building scientists and manufacturers.

Brian Burton is the author of Building Science Forum and is serving on CSA’s Fenestration Installation Technician Certification Committee. Brian is a research and development specialist for Exp (The new identity of Trow Associates). He can be reached at brian.burton@exp.com or through www.exp.com .