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Insulating Issues: July/August 2010

Is glass under attack?


July 1, 2010
By Margaret Webb

Topics

Today there are more and more codes that manufacturers have to stay on
top of in order to ensure compliance; the National Building Code of
Canada (NBCC), National Energy Code for Buildings, (NECB), Canadian
Energy Star program requirements and provincial requirements. A task
group will be starting work shortly on revising the National Energy Code
for Houses. Another code to keep track of.

Today there are more and more codes that manufacturers have to stay on top of in order to ensure compliance; the National Building Code of Canada (NBCC), National Energy Code for Buildings, (NECB), Canadian Energy Star program requirements and provincial requirements. A task group will be starting work shortly on revising the National Energy Code for Houses. Another code to keep track of.

For companies that operate in Canada and the U.S., the list just explodes. There are the I-codes (building, residential and energy), ASHRAE, NFRC, Title 24, Energy Star, Building Star, R 5 and the list goes on and on. 
It’s a lot of work to stay informed. Larger companies often employ and rely on a full-time code specialist for current and proposed code revisions. SME’s (small to medium enterprises) often rely on trade associations and colleagues for information. Even so, Canadian based trade associations do not employ a full-time code consultant so manufacturers at a minimum need to stay informed on which code bodies affect them, which sections apply and the timing of the various code cycles (3 or 5 years). The worst case scenario is that manufacturers find out about the changes when their product fails to comply with the codes requirements.
 
Of concern to the industry at the present time are new requirements to reduce the per centage of fenestration in buildings. This is known as the Window Wall Ratio (WWR).

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Published originally in 1997, the National Model Energy Code for Buildings was not adopted by the provinces and as a result has never been enforced in Canada. The Canadian Commission on Building and Fire Codes (CCBFC) established a task group composed of representatives from various stakeholders groups to review the 1997 model code and revise sections to reflect current requirements.  Publications of the National Energy Code for Buildings (NECB) is expected sometime in 2011. At the same time, ASHRAE is revising the 90.1 standard in the U.S.

Both codes have included new prescriptive and performance based requirements for the amount of glass to building ratio. Currently, the WWR is 40 per cent. However, with the new codes, this will be restricted to 30 per cent. The debate about 40 per cent versus 30 per cent glass area impacts both the prescriptive and performance path of compliance with a direct impact on the prescriptive path.

What is of real concern to the industry is that no data has been presented or reviewed that supports this reduction in the WWR.
 
Lawrence Carbary’s paper “Comparisons of Thermal Performance and Energy Consumption of Facades used in Commercial Buildings” presented at the 2009 Glass Performance Days conference included data to support that buildings with no glazing, irrespective of climatic zones were not the most energy efficient and that air infiltration had the most impact in determining energy use of the facade, not glazing performance.

IGMA submitted negative comments to both codes regarding the WWR reduction. It still remains to be seen what will be included in the NECB which will be out for public review the fall and IGMA encourages all manufacturers to comment during the public review period.

ASHRAE 90.1 will be published with the 30 per cent WWR (pending resolution of submitted appeals) however there is a second addendum that will be included with the option to have 40 per cent WWR with daylighting controls. Originally it was believed that this second option would be delayed but with support from other organizations, this will be included.
 
Glass manufacturers are constantly bringing new products to market with better and better U-values. There are also other products which significantly improve performance. These include electrochromics, new films and coatings which have not been taken into consideration.
 
It is the responsibility of our industry to educate the task group and committee members that are making decisions that affect us.

Margaret Webb is the executive director of the Insulating Glass Manufacturers Association (IGMA). She can be reached at  mwebb@igmaonline.org .


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