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Conservation of Fuel and Power

Part L / Window Energy Ratings

In England and Wales, Building Regulations for the conservation of fuel and power are covered by Part L and its accompanying "Approved Documents". The current Part L regulations came into effect on April 6th 2006 and are based on carbon emission calculations with maximum limits for the window U values which we summarised in Bulletin 7. 

One of the most significant changes at that time was the introduction of  Window Energy Ratings (WER) as an alternative to U values as a criterion for compliance.  Window Energy Ratings are a much more accurate indicator of the energy performance of a window because they take a range of factors into account, including the useful solar heat gain. We have explained Ratings in more detail in our Window Energy Ratings Bulletin 3

In response to requests from the Industry for a clear long term framework, the Government Department for Communities and Local Government (CLG) has subsequently publicised a roadmap for future changes in Part L. Changes will be introduced in 2010, 2013 and 2016 gradually improving the energy efficiency of buildings. By 2016 new homes are intended to be zero carbon. We have summarised the expected changes in 2010 in our latest update Part L Bulletin 8.

Window Energy Ratings are  administered by the British Fenestration Rating Council (BFRC).  Detailed information on obtaining BFRC Ratings for windows can be found on www.bfrc.org

To view details of the Pilkington range of Thermal Insulation glass please click here.