Glazing areas are limited as part of new Canadian energy code

The new National Energy Code for Buildings (NECB) that was just published in November has several important differences from its predecessor.  The predecessor was the 2005 Model National Energy Code for Buildings, but the Codes committee decided to drop “Model” from the title of the 2011 version.

Heather Knudsen, technical advisor at the National Research Council’s Canadian Codes Centre in Ottawa explained some of the new energy code’s characteristics at Construct Canada on November 30.

Most importantly, the new code has raised the bar and those that adopt it will operate 25% more energy efficiently compared to buildings that comply with the 2005 version.

At the same time, Knudsen pointed out that the new code is still intended only to prescribe minimum requirements. The objective of the NECB is simply “to avoid excessive use of energy” in buildings, said Knudsen. Incentive programs such as LEED and CBIP will require higher energy-savings.

As with the 2005 energy code, users can follow either a performance path, which involves modeling the whole building and treating it as entirety. Or they can follow a prescriptive path with trade-off options within specific building components.

However, in this new energy code trade-offs are permitted for HVAC systems and service water heating, and for interior lighting. These were not included in the 2005 MNECB.

Another major difference in the 2011 NECB, one which will have an impact on the architecture of buildings, is a FDWR (fenestration-door-wall ratio) requirement. The ratio will limit the amount of glazing, for example. This could mean that condominiums with wall-to-wall glass might not be an option for any developer who wants to conform to the energy code.

The FDWR varies depending on the climate zone.  In Vancouver or Toronto which has 4,000 heating degree days would be allowed 40% fenestration, Knudsen said, whereas in Yellowknife, NWT which has 7,000 heating degree days, a building would only be allowed to have 20% of its envelope as fenestration-door openings.

Another difference in the new code is that the source of the energy is not a factor. The 2011 code is “fuel-source neutral” Knudsen explained. Also, the energy-use benchmarks don’t vary by administrative region, but rather by climate zones, measured by the number of heating-degree days.

The NRC is going to have free on-line presentations about the new energy code at the National Codes website in early 2012, see www.nationalcodes.nrc.gc.ca

Ontario was the only province that has adopted the 1995 Model National Energy Code for Buildings.