Coatings have been the great saviour of glass in an increasingly energy-conscious architectural world. Alongside Pilkington's self-cleaning Activ glass, the main line of development has been glass systems and coatings that address the issue of energy conservation.
E-glass was probably the big breakthrough, although urban myths circulated about the inevitably diminished light transmission requiring so much electric lighting in the rooms behind that the cost/embedded energy/expended energy equations did not make a lot of sense. If there was a whiff of truth in that - and it seems there was not - new coatings have been devised which ensure that light transmittance is at optimal levels. German company Interpane Glas Industrie recently released its Low-E2 coating technology, especially for use in 'large glazed expanses in sunny residential areas'. The figures for this iplus SE (Super Energy) double-coating glazing are a high light-transmittance factor (T) of 71 per cent and a Ug value of 1.1W/m 2K. The same company produced the glass for architectural legend Peter Smithson's last commission, a new furniture museum - the Kragstuhlmuseum, Lauenf÷rde, Germany - that was opened last year. The all-glass elevations, with their hexagonal pattern of glazing bars, are made from Interpane's ipasol neutral 73/39, whose light transmission is 73 per cent with a Ug value of 1.1W/m 2K. The figure of 39 refers to the solar factor. The clarity of the coating allows true-colour examination of the exhibits. The north-facing skylight in ipasol 50/25 brings light into the middle of the building, and has a light-transmittance factor of 50 per cent (which is as good as you get with the very low solar factor of 25 per cent). One of the nice conceits of the building is the red-painted chairs, which form 'pinnacles' to 10 towers as part of the external facade.