Natural Resources Canada
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Personal: Residential
Energy Efficiency Ratings



Window Styles


FAW   Fixed awning
AWS   Awning (single)
AWD   Awning (double)
FCA  Fixed casement
CAS   Casement (single)
CAD   Casement (double)
SHU  Single hung
DHU  Double hung
THU  Triple hung
SSL  Single slider
DSL  Double slider
TSL  Triple slider
HOP  Hopper
PIC  Fixed (picture)
PTC  Pivot (center)
TNT  Dual action (tilt-turn)

ACL  Aluminum clad
ALU  Aluminum
AVY  Aluminum/Vinyl
AWO  Aluminum/Wood
CMP  Composite
FBG  Fibreglass
FOF  Foam filled
MRE  Metal reinforced
STL  Steel
VCL  Vinyl clad
VYL  Vinyl
VWO  Vinyl/Wood
WOD  Wood
WFG  Wood/Fibreglass
WRE  Wood reinforced

Energy Efficiency Values

U = U-value (W/m² – K) – The lower the number, the more energy efficient the product.

SHGC = Solar Heat Gain Coefficient – The higher the number, the higher the solar gain.

ER = Energy Rating (W/m² or dimensionless) – The higher the number, the more energy efficient the product.

The ER (Energy Rating) format was changed to all positive numbers (dimensionless) in October, 2004 by CSA (Canadian Standards Association) to address consumer confusion over negative numbers. The older format had a mixture of negative and positive numbers (W/m²). In our listings, all ER numbers that appear in the older format are shown in bold coloured type. An approximate conversion to the new format can be made by adding 33 to these numbers.