A change in Building Regulations (Document L1B) in October 2010 required all window installations from that date to have a thermal performance of 1.6 which is equivalent to a window energy rating of "C".
Although a small contributor to a WER, over the past few years suppliers of spacer bars have been claiming certain values. Many of these values have been disputed and to resolve the problems an agreement was reached by the Glass & Glazing Federation (GGF) and the British Fenestration Rating Council (BFRC) whereby testing must be undertaken to ensure that thermal values are comparable.
A spacer bar manufacturer now has to submit data in the form of a Bundesverband Flachglas (BF) data sheet. This now means that all values are comparable and have been subjected to exactly the same tests.
Sealant depth is critical to the performance of a double glazed unit. The manufacturers guidelines should be followed and the units produced should be representative of the System Description used for the Part 2 and 3 testing.