Her Royal Highness The Princess Royal today opened the seven storey offices of Marsh and McLennan Companies designed by Foster and Partners. The development provides 42, 000 square metres of highly energy-efficient office space in two blocks, broadly triangular in plan, which are linked by one of the largest glazed atriums in Europe. This semi-public space allows pedestrians to use it as a sheltered thoroughfare. The building replaces a sixteen-storey 1960s office development which obstructed important view corridors between Greenwich and St Pauls Cathedral and between the Monument and the Tower of London. The new buildings restore these views and open up this historically important site, creating a new public plaza with trees and water features. The engineering of the atriums glass walls in excess of twenty metres in height is technically highly advanced: they are hung like curtains from tension cables stretched between the two buildings. They terminate one storey above ground level, creating an open space through which the public can move freely. In order to prevent the faades from swaying under wind loads, they are tied back to the columns that support the glass roof with glass needles bora-silicate glass pipes, more commonly used to transport corrosive chemicals. Each needle consists of two layers of glass an inner structural tube and an outer protective layer. A PVB interlayer holds the two together. The tubes have been pre-compressed in order to overcome the inherent weakness of glass when under tension. Each tube takes the wind load of almost 50m2 of facade. The tubes have been tested to three times their design load. They have never been used in an architectural application before. The building is highly energy efficient, incorporating blade-like aluminium louvres for solar shading, displacement ventilation and high insulation levels. The lobbies incorporate two large wall paintings by the renowned American conceptual artist Sol LeWitt.
