A glass facade that`s like lace

The new “John Lewis” department store in the British town of Leicester is covered with a dazzling, lace-like curtain that at night is backlit in 256 colours. It is actually a double facade of structural glazing with a very elaborate patterning. With the radical yet inspiring proposal to use a transparent, elegantly patterned full glass facade as an outer skin, Foreign Office Architects (FOA), London, won the competition for the design of the 25,000 square metre department store. The facade glazing “ipachrome design” by Interpane allows for creative yet functional optics: The design, which was applied in a sputter process, also serves as solar and visual protection and allows for variations in the transparency of the facade.

The English town of Leicester is known for its multiculturalism. Every fourth inhabitant has Indian roots. More than half of the youngsters there come from India, Somalia, Jamaica, Bangladesh, Uganda, or Pakistan. In some schools, more than 70 different languages are spoken. And Leicester’s economy is booming – restaurants, textile factories, fashion stores. Now, the new “John Lewis Department Store” can be found right in the middle of this illustrious society, and with its patterned, net-like facade it not only gets many admiring looks, it also fits beautifully into this colourful city. At night, the noble facade is illuminated from the inside in 256 different colours.

Structural glazing with design coating

Structural glazing provides for a particularly harmonic facade appearance, because the mountings for the individual glass panes are invisible from the outside. The glass panes for the facade of the “John Lewis Department Store” were lowered from up above and were then horizontally glued. Apart from a very harmonic and homogenous optical appearance, this also brings about practical advantages: Rain will rinse any possible dirt off the glass facade. In order to protect the inside from outside views, but also to maintain maximum transparency, a sort of 3D architecture was created. The facade was equipped with double glazing, or two layers of the “net curtain”. In addition, the inner and outer patterns were offset against each other. From the outside it looks as if the patterns lie on top of each other in order to keep viewers from looking inside.

The pattern itself is a new, partial coating, which also allows for delicate, artistic types of object design: “Ipachrom design” was developed and designed by Interpane in Plattling, Germany. More than 5,000 square metres of glazing and 625 panes of 2.4 by 5.4 metres each comprise this integral area. The pattern was designed in such a way to establish flowing transitions in order to produce the appearance of a single unit.

The ipachrome design multiple layer system lets the pattern appear like a highly reflective conventional silver mirror from the outside. Unlike other reflective coatings, this one is highly resistant to high humidity. At the same time, the eye-catching ornaments also serve as solar protection, with a transmittance of only 4 per cent. The glass panes themselves are made of laminated sheet glass (LSG), which is comprised of two layers of 10mm heat-strengthened glass.