U-factor can be expressed in metric units (W/m2·K) or imperial inch-pound units (Btu/h·ft2·F).
To convert imperial u-factors to metric u-factors, multiply by 5.678.
Example: My contractor has given me a quote for five new windows that I would like to replace. My contractor says they have a U-factor in imperial units (Btu/h·ft2·F) of 0.21 and I want to know what that is in metric units.
0.21 x 5.678 = 1.19 (W/m2·K)
New windows typically have a U-factor between 1.00 and 1.80 (W/m2·K), which converts to between 0.18 and 0.32 (Btu/h·ft2·F).
In order to receive a window rebate through the CleanBC Better Homes and Home Renovation Rebate Program, your windows must have a metric U-factor (W/m2·K) of 1.23 – 1.40 for Tier 1 rebates or a metric U-factor (W/m2·K) of 1.22 or less for Tier 2 rebates and must be listed with one of the following certification bodies:
- Canadian Standards Association (CSA)
- Intertek Canada (Intertek)
- Labtest Certification (LC)
- QAI Laboratories (QAI)
- National Fenestration Ratings Council (NFRC)
Learn more about this rebate here.