This measures how easily heat gets through your windows and doors. The higher the U-Value, the more heat escapes, so the lower the U-Value, the better. A lower U-Value means your window keeps more heat in and your home is warmer for longer.

To get a U-Value, heat transference rate is divided by the temperature difference on either side of the window or door. The end value is in watts per square meter per Kelvin W/m2K. (1°C = 1Kelvin). Our A++ rated uPVC triple glazed flush windows have a U-Value of 0.95 W/m2K.

This means that for every degree of difference between the inner and outer panes of glass, 0.95 watts of heat energy is lost per square meter of glass. This is a very low amount of heat energy escaping, meaning these windows are very good at locking in the heat.