"The Cube" – a glass box defies the sun
"Space frame system": structural glazing for the highest transparency and maximum solar control
The glass “Cube” in the new Spanish financial centre near Madrid is 21.6 metres high and 30 metres wide – a cube shaped bank lobby, designed by the architect Alfonso Millanes Mato. Inside, trees up to twelve metres high throw dynamic shadows and provide a pleasant room climate. The facade has been constructed without any framework structures for the glazing itself. Instead, a so-called "space frame system" is used, which connects the structural glazing facade to a filigree support structure made of steel. The protection of the lobby from the intense Spanish sun is ensured by around 3,500 square metres of ipasol solar control glass.
Since the beginning of 2009, the headquarters of Banco Santander Central Hispano have been located in the financial centre “Ciudad Financiera”, twelve kilometres from Madrid, in Boadilla del Monte. On an area of more than 160 hectares, the € 270 million project in a rural environment offers not only 100,000 square metres of office space, but also recreational facilities: green space and sports grounds, shopping zones, a golf course and a kindergarten are available to the bank’s members of staff.
Visitors enter the company’s headquarters via “El Cubo”. The 900 square metre lobby impresses with a lot of daylight and views to all sides. A “forest” inside provides cool shade and fresh air. Flooded with light and still protected from the Spanish sun, minimal use of steel and nevertheless a stable structure – these were the high requirements on the design. The entire construction has therefore been realized as structural glazing in the form of a cube, using the space frame system “Octatube”. So-called “Quattro Nodes” create spatial structures of steel and glass. They connect the glazing to the stabilizing main structure via four screw points per inner glass pane.
The solar control glass ipasol neutral 48/27 was used for the cube’s sides – it ensures neutral transparency, lots of daylight and a high degree of solar control, all at the same time. Due to the low total solar energy transmittance (g value = 27 percent according to EN 410), the interior heats up only to a minor degree even during strong solar irradiation – this reduces the requirement for air-conditioning. Nevertheless, the solar control glass has a relatively high daylight transmittance (tL = 48 percent). In winter, the Ug value of 1.1 W/m²K (according to EN 673) provides effective insulation.
While the planners deliberately aimed at a neutral appearance by using ipasol neutral 48/27, the glass ipasol sky 30/17, which has been used for the roof area, offers an even higher level of solar control. At 17 percent (according to EN 410), its g value is extremely low. The entire glazing is made from thermally toughened glass on the outside and from heat-strengthened glass on the inside.