A superior technology designed to minimise energy loss through your windows

Window performance

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Building Regulations and Window Energy Ratings

UK Building Regulations

UK Building Regulations dictate that all new and replacement windows must meet minimum requirements for thermal efficiency. The current requirement is that windows attain a whole window U-value of 1.6 Wm²K or better, or a Window Energy Rating (WER) of 'C', 'B' or 'A'. Proposed changes suggest that these requirements may shortly change to a U-value of 1.4 Wm²K or a minimum WER of a 'B'.

The energy rating of a window is influenced by the window frame, glass type and the structure and components of the glazing units. It is the recipe of all of these factors which contributes towards achieving improved thermal efficiency. Please click here to view a comparison chart of window thermal performance with various combinations of frame type, glazing type, and spacer type.


Thermobar is a Passive House certified component - click here.

Building Regulations and WERs Page 1

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