Main Tower To create a low-energy landmark building, designed to provide a spacious and well ventilated work environment. Sustaining low operating costs within the building was a prime concern of the architects involved in the project. The 200m tall Main Tower is home to several prominent enterprises, including the Landesbank of Hesse and a television studio of the Hessischer Rundfunk and is situated in the financial centre of the city. The 2550 windows in the tower building have created the first fully-glazed facade on a high-rise building in Europe. Maintaining the clean sightlines of the facade was made possible by the use of Securistyle's parallel hinges. This entirely glass facade allows plenty of natural light into the building and the use of Securistyle's parallel hinge system supports the low-energy ideal of the architects, whilst allowing for natural ventilation in a safe and secure environment. The air exchange provided by the Parallel system is equivalent to a conventional vent opening of 100mm or more, therefore providing a sustainable alternative to a complete air conditioning system within the building. All the windows in the tower can be controlled by central building management systems. This facilitates variable opening distances as part of a mechanised solution responding to climate changes.