The BFRC tested and approved PVC window system we supply and install, as well as being the first window created to gain the new 'A' Rating for energy efficiency was also the first fully reinforced double glazed window system to excel the tests. The Window Energy Ratings are a simple way of telling how energy efficient your new windows and doors can be. In the process of creating your individual windows and doors we will design them to keep the heat in and the elements out.