document l glass

 

Glass Systems Ltd does not know into which type of frame our units are being glazed, and is not therefore responsible for the overall U-value of the finished window.  It is up to our trade customer to confirm that the glass they order combined with the frame into which it is glazed, conform to current legislation. 

However, the table below shows U-values of a low E unit compared to a traditional unit with two clear panes of glass.  For other glass types please contact our sales office.

Hard Coat Low E U - Values
	12mm	12mm	16mm	16mm	20mm	20mm
U - Values (w/m2.K)	air	gas	air	gas	air	gas
4mm clear/4mm clear	2.8	2.6	2.65	2.55	2.7	2.55
4mm clear/4mm low E	1.9	1.6	1.7	1.5	1.7	1.5

 

When reading U - the values of the glass emissivity need to be known.

Different Low E glass's have difference emissivity rates.

The figures shown above are for a low E glass with an emissivity of En 0.15.

Trade names for Low E glass with this level of eissivity are Pilkington's "K" and Glaverbel's "Planibel G" both of which are "Hard Coat" Low E glass's.