The new legislation means that the thermal regulations for windows and doors will change, to limit heat gain and loss.
Since the changes to the regulations were announced the System Houses who design the windows and doors have been busy optimizing and testing their products to ensure they fully comply with the new regulations.
The look and style of the external aesthetics of the products have stayed the same. While internally the frames have been modified to help achieve the new standards. Then rigorously tested to ensure they meet the new minimum U-values/Energy ratings set out in the legislation.