Window Energy Ratings were designed to help homeowners choose the best windows for their property. They use a mathematical formula that takes into account the energy performance of all the components of a window, such as the frame, glass, spacer bar, to produce a whole window U-Value and Window Energy Rating (WER).
All new and replacement windows must have a WER of C or above, or have a U-Value of 1.6 W/m2k or lower.
Read our blog for more Window Energy Rating details.