Building regulations – Window Energy Ratings or WER’s
Window Energy Ratings or WER’s were introduced in the UK around 2004 and are issued for the thermal efficiency for the whole of the double glazed windows unit (Not just the double glazed panes).
The British Fenestration Rating Council (BRFC) manages all the ratings and it works on a Alphabetic scale of A to G, with G being the lowest rated window.
A small thing to note here is that the WER is not there to tell you about the manufacturing process or how well the window was built; it refers solely to the heat retaining properties of the unit itself. So in theory you could have a “C” rated window that is well made and fitted properly that does a better job than an “A” rated window that was installed badly. Choosing the right installer is therefore just as important as choosing an efficient window.
At the moment, the UK building regulations (10.2010 Part L) asks for replacement windows to be at least rated “C”. The UK Energy Savings trust has a scheme that can recommend certain window products that are in band “B” or higher. This is identified by the EER or “energy efficiency recommended” label
Planning permission may be required in certain areas of the UK, depending on your individual property, but it’s a high probability you will need some form of permission if you live in an Area of Outstanding Natural Beauty, a UK National Park or if your building is “listed”.
You would need to consult with your local planning department to find out more.