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U-Values & Energy Ratings

U-value calculations (sometimes referred to as heat transfer coefficients or thermal transmittances) are used to measure how effective the components of a building’s fabric are as insulators i.e. preventing heat from transmitting between the inside and the outside of a building.


As energy prices continue to soar and the awareness of sustainable buildings continues to grow, performance measures such as u-values are becoming increasingly important. Compliance with building regulations requires lower than ever u-value performance, which means changes in the design of buildings, both in the use of materials (e.g. insulation), the make up of the building elements (e.g. cavity walls and double glazing) and the overall make up of a building’s fabric (e.g. reducing the proportion of glazing).

UKTC undertake u-value calculations for windows and doors to meet the requirements of the building regulations, Part L. Our engineering team can also help to design a cost-effective research and development programme to help you maximise the performance of your windows and door products to your specific requirements.


BS EN 673-2011

▪ BS EN ISO 6946:2017

▪ BS EN ISO 10077-1:2017

▪ BS EN ISO 10077-2:2017

▪ BS EN ISO 10456-2007

▪ BS EN 14351-1:2016 + A2:2016

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