The window system heroal W 72 was the system of choice. It perfectly meets the demands on this unparalleled urban office building – because it is innovative, sustainable, cost-effective and energy-efficient. The curtain wall was supplemented by ventilation flaps heroal W 72 VF, which offer numerous advantages. All ventilation flaps can be opened and closed independent of users, which makes possible a controlled, natural ventilation around the clock. Just as required by the customer, they harmoniously integrate into the curtain wall, emphasizing the individual character by setting visual accentuations. The system solutions are rounded off by the project door system heroal D 72, which stands out in the highly frequented entrance area of Kotelna Park II.