Conservatories and Sunrooms - Pilkington K Glass, Low E Glass, Suncool Glass.

What is the U Value of a typical Double Glazed sealed unit?

The following table shows some typical U values for vertical insulating glazing Pilkington Insulating Units and the effect of using K Glass, Argon and varying cavity widths. The lower the U Value - the better the insulator. U-value is the measurement of heat transfer through a given building material, glass, etc. In the UK all U Values are quoted as W/m²K.

U values based upon 4mm Pilkington Optifloat thickness. (NOTE: Optifloat is the name given by Pilkington to "normal" float glass)

Figures determined in accordance with the requirements of BS EN673: 1998 for `normal' exposure conditions. U values are rounded to the nearest 0.1W/m2K as described in clause 9 of the standard. The total overall U value of a window can be calculated taking into account the insulation of the glazing, the unit spacer and framing. 

We often get asked what is the best cavity width to use in a double glazed sealed unit. As can be seen above there is very little difference between a 16 mm and 20 mm cavity.

You will also note that adding Argon Gas alone has very little effect in improving the U Value. Only when the Argon is combined with Pilkington K Glass is any significant improvement made.

SPECIAL NOTES

	Pilkington are only one of many glass suppliers world-wide. We are only giving their products so much prominence here because of their large market share in the UK.
	If you live in Australia we suggest you have a look at the Pilkington - Australia web site at http://www.pilkington.com.au
	Different parts of the world quote U Values in different ways. In the UK all U Values are quoted as W/m²K. The lower the U Value - the better the insulator. U-value is the measurement of heat transfer through a given building material, glass, etc