Thermal Efficiency

The Window Energy Rating (WER) is the Government-backed method of assessing and ranking the energy efficiency of a complete window. Taking into account its U-value, solar gain and air infiltration, the scheme allows easy comparison of the energy efficiency of competing windows with A being the best.

The energy performance of an IGU or the glazing itself can be improved in a series of steps to gradually improve the WER band achieved; firstly argon filling improves U-value, then low iron glass such as Pilkington Optiwhite™ E as the outer pane improves solar gain, and the addition of a warm edge spacer bar improves
the U-value of the whole window.

Currently Building Regulations demand a minimum of Band C but we expect this will tighten with changes to Part L in 2013 and then again in 2016.