What do we mean by U value?
U value is a means of comparing the heat lost through various parts of a building. A part of a building with a U value of 4.0 W/m²K will lose twice as much heat as one with a U value of 2.0 W/m²K.
The lower the U value the less heat you lose through your windows
Living with your windows
Draughty windows affect your comfort
Draughts through your windows can create cold spots around the room, particularly around the legs and feet, as a result heating is normally turned up higher to compensate, even the dog will want to jump up on the settee next to you. The tight tolerances designed into our secondary glazing system keep cold air and dust out whilst retaining the warm air in the building.
Live right up to your windows
Air permeability Test
BS 5368:Part 1
BS 6375:Part 1
This defines the ability of the window to resist air penetration when it is subjected to differential pressure and is a measure of the air which seeps through the test window at given test pressures.
The average amount of air that leaks through a metre of the opening weather seal (as seen from the inside of the window) is measured and the measurements are calibrated in cubic metres (m3), per hour, per metre of opening seal. A two-panel slider 1215 W x 1193 H was fitted to a test rig at BSI in Hemel Hempstead.
The sample met the stringent test result of Pressure Class 300Pa.