Technical Booklet F1 Conservation of Fuel and Power in Dwellings·Page 30·2.42
U-value Calculation Methods
U-values must be calculated using methods and conventions in BRE Report BR 443, based on whole unit performance. For windows, the U-value can be taken as the value for the smaller standard window defined in BS EN 14351-1, the standard configuration in BR 443, or the specific actual unit.
The U-values should be calculated using the methods and conventions given in BRE Report BR 443 Conventions for U-value calculations, and should be based on the whole unit (e.g. in the case of a window, the combined performance of the glazing and the frame). The U-value of windows can be taken as the value for – (a) the smaller of the two standard windows defined in BS EN 14351-1; or (b) the standard configuration given in BR 443; or (c) the specific size and configuration of the actual unit.
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