By Ray McGowan
When Canada’s most populous province makes a change affecting residential design and construction, the industry takes notice. Ontario’s Green Energy Act is designed to expand use of renewable energy and promote energy efficiency. It was recently amended to include minimum energy requirements for residential windows as of January. These windows must have U-factors less than 2.0 W/m2K (0.35 Btu/hr/sf/F) or meet an energy rating greater than 17 as cited in Canadian Standards Association (CSA) A440.2, Fenestration Energy Performance.
The Green Energy Act will require most residential windows be rated and labelled through a third-party organization’s certification program. Manufacturers can either get their windows certified CSA A440.2, through an organization approved by the Standards Council of Canada, or by participating in the National Fenestration Rating Council’s (NFRC’s) rating and labelling program.
Fenestration Canada, an association of window and door manufacturers, outlined the act’s requirements for residential windows this spring in a special webinar on the topic. While there are some exemptions to the certification requirements—such as door sidelites, replacements for historic windows, replacement glazing, and certain decorative and custom openings—all other residential windows sold in the province will need energy performance certification. The requirement applies to windows in buildings used partially or entirely for residential purposes 600 m2 (6458 sf) or less in size and three storeys or fewer in height.
Like the provincial energy code, the Green Energy Act also includes requirements for basement windows incorporating a load-bearing structural frame. Those types of windows need dual panes and a low-emissivity (low-e) coating.
NFRC’s trusted rating and labeling program
For nearly 25 years, NFRC has been a source of independent energy performance ratings for residential and non-residential windows, doors, skylights, and other fenestration. While NFRC has its roots in the United States, it has helped Canada—and other countries—implement window energy rating systems.
NFRC-certified residential windows feature a temporary label, listing energy performance values, attached by the manufacturer. Building officials rely on this label to verify windows meet or exceed energy building codes. Manufacturers also include a permanent label, required by NFRC. The small, rectangular label is usually applied to an inconspicuous spot on the window, such as the top sill. A product must include an NFRC label for its ratings to be acknowledged as ‘certified.’ Without one, even a window that went through NFRC’s certification procedures is not recognized as certified.
NFRC’s certified ratings help design/construction professionals—and homeowners for that matter—compare product performance. American Society of Heating, Refrigerating, and Air-conditioning Engineers (ASHRAE) 90.1, Energy Standard for Buildings Except Low-rise Residential Buildings, which British Columbia references, requires NFRC ratings, and EnergyStar demands NFRC certification as a prerequisite for program qualification. (All EnergyStar windows already meet the Green Energy Act’s.)
In Canada, the temporary label lists NFRC-certified ratings for solar heat gain coefficient (SHGC), U-factor (i.e. rate of heat loss), and visible transmittance (VT). Manufacturers must list these three performance numbers. Some manufacturers also include an optional rating for air leakage (AL).
SHGC is rated on a scale of 0 to 1, with a lower figure indicating better performance at blocking the sun’s heat. In some cases, particularly in Canada, where passive solar heat in winter is welcomed, a higher SHGC may be preferable, because it allows more heat from the sun to enter a room through the window during the heating season.
U-factor is especially important when specifying windows for Canada’s climate. The performance figures for NFRC-certified windows sold in Canada list U-factor in imperial and metric units, in both English and French. With the imperial units, U-factor ratings generally fall between 0.09 and 1.20 Btu/hr/sf/F (0.5 to 6.7 W/m2K). A lower U-factor value indicates better performance at preventing heat loss.
For VT, NFRC uses a scale of 0 to 1; the higher the number, the more visible light is transmitted through the glass. Air leakage ratings typically fall between 0.5 to 0.15 L/s/m2 (0.1 and 0.3 cfm/sf). The lower the figure, the better a product keeps air out.
These ratings can help architects and general contractors make informed decisions when choosing windows for their projects. NFRC-certified ratings also can be used to demonstrate a residential product’s performance values meet provincial and/or local code. In the case of Ontario, they also show compliance with the Green Energy Act’s requirements.
Ray McGowan is a senior program manager for the National Fenestration Rating Council (NFRC). He works with many trade organizations on fenestration matters; as a voting member of American Society of Heating, Refrigerating, and Air-conditioning Engineers (ASHRAE) SSPC 90.1/Envelope Subcommittee and ASHRAE Fenestration Technical Committee (TC 4.5) Vice-chair/Research Subcommittee chair. McGowan previously consulted for the EnergyStar program, marketed commercial HVAC equipment, and tested and designed power equipment for the U.S. Navy and electric utilities. He holds a bachelor of science degree in mechanical engineering and an MBA degree in finance. McGowan can be contacted by-email at email@example.com.