13 e inschalige Fassade mit Lüftungsklappe und Drehflügel zur Lüftung (siehe Abb. 2). Behörde für Stadtentwicklung und Umwelt, Ham burg-Wilhelmsburg, geplante Fertigstellung 2013, Architekten: Sauerbruch Hutton 14 zweischalige Fassade mit hinterlüfteter Prall scheibe, Lüftungsklappe mit Volumenstrom begrenzer, Drehflügel zur Reinigung (siehe Abb. 5). ADAC-Hauptverwaltung in München 2012, Architekten: Sauerbruch Hutton
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13 S ingle-shell facade with side-hung sash for venti lation and ventilation flap (see ill. 2). State Ministry of Urban Development and the Environment, in Hamburg-Wilhelmsburg, planned completion 2013; architects: Sauerbruch Hutton 14 Double-shell facade with ventilated baffle plate, side-hung sash for cleaning, and ventilation flap with integrated volume-flow control, produced by EMCO (see ill. 5). ADAC Headquarters, Munich 2012; architects: Sauerbruch Hutton
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Each facade module possesses a manually operated sash employing triple glazing, as well as a lateral ventilation flap of insulated aluminium (ills. 1, 13). A conscious decision was made to do without air conditioning. As a precaution, the ventilation flaps are situated behind the outermost metal cladding. Consequently, the intake air is protected from wind and rain as it passes though the lateral reveals – providing ventilation that is free of drafts and apertures that are safeguarded against burglary. In addition, night air can be used to cool the interiors. A glare-protection screen was installed on the inner face of the hinged sash, and on the exterior, the louvres – concealed by a continuous ceramic ribbon – provide sun protection. At the parapet level a further continuous ceramic band safeguards against falls. Ventilation flaps in the facade can also contribute to creating an acoustic link to the outdoors in buildings with thermally and acoustically insulated envelopes. At the Elbe Philharmonic Hall in Hamburg, flush oval operable sashes – not discernible as such in the facade – are integrated in the curved centre posts between the flat, concave and convex facade components. Their purpose is to allow persons in the building to perceive the scents and sounds of the harbour (ill. 3). In the apartments and hotel rooms, the sashes can be operated manually; in the foyer they are motor-operated and are also part of the smoke purge concept. A textile blind on the inner face provides glare protection, while sun protection is achieved through a combination of the use of different coatings and screen-printing on the panes of the double-glazing. Double-shell facades with volume-flow control and operable sashes The 92-metre-high ADAC Tower, designed by Sauerbruch Hutton, has a double-shell facade of aluminium and glass, with a colour scheme containing 22 different colours (see p. 126ff.). Every facade module’s inner face is equipped with two operable sashes for cleaning and a ventilation flap (ills. 5, 14). The storey-high facade modules are protected against wind by a baffle plate with ventilated cavity. The
ccordion shades in between provide pro a tection from sun and glare. On office levels without partition walls, natural ventilation employing facade flaps would be problematic, because during windy periods, differences in pressure and suction forces on the opposite facades would cause uncontrolled drafts inside. This is where constant volume-flow control enters in: it ensures that the air-exchange rate is constant, reduces the air conditioning’s energy consumption, and provides fresh air to the rooms. Air – exhaust air when pressure at the facade is negative and intake air when pressure is positive – passes through the unit’s four valves for intake air, exhaust air, fresh air and outgoing air. The lower valve closes at 120 m3/h (±10 %), without auxiliary energy, to limit the air-volume flow. Even when winds are strong, the control unit operates quietly and independently, and requires no auxiliary energy. When the pressure difference is minimal, the air automatically bypasses the control unit. Second-skin facade for natural air supply and exhaust through air cavities In comparison to a baffle-plate sheathing, the ventilation apertures of a second-skin facade are completely protected from wind and rain. This facade type, which was developed in the 1980s, is also a double-shell facade with operable apertures. Accordingly, despite high wind loads, even skyscrapers such as the Commerzbank in Frankfurt – at 257 m, it was for many years Euorpe’s tallest – can be ventilated naturally. Second-skin facades can be executed with a controlled ventilated cavity, or with a continual flow of air through the cavity. Systems with a controlled ventilated cavity have a closed outer facade with intake and outtake apertures with which the air temperature in the intermediate space can be regulated. The 70-metre-high City Gate in Düsseldorf (ill. 7) is one of the most complex examples: the corridor within the facade is up to 140 cm wide, has safety rails, and is accessible to building occupants. To ventilate their rooms, the users open the hinged wooden sashes of the inner skin. The corridor is subdivided vertically by glass fins. For ventilation purposes,
two adjacent facade bays are merged into one segment. This diagonal ventilation prevents short-circuit currents of exhaust air between the individual storeys. In this way, exhaust air cannot mix with fresh intake air. Ventilation units separate the facade’s intermediate space between floors. The ventilation apertures are equipped with ventilation flaps. If the outdoor temperature is lower than the indoor temperature, the cooler exterior air is allowed to enter the building through the ventilation units and the inner facade. If the outdoor temperature is higher than the interior temperature, ventilation flaps can be closed to reduce thermal transmission from the outside to inside and thereby lessen the cooling requirement. The natural air stream through the facade’s intermediate space makes it possible to do without air conditioning in the office spaces. Closed-cavity facades (CCF) with decentral ised ventilation units and operable apertures The closed-cavity facade is a closed doubleshell facade. This new facade type offers two options for decentralised natural ventilation: installation of facade ventilation units, or construction of fully operable CCF modules. Clean, dry air is supplied continuously to the sealed interstitial space accompanying each box-type window via tubes with a diameter of just a few millimetres. The air is supplied via a compressed-air system located in the building services room. Further supply occurs via a low-pressure pipe system as well as a tube system. All control units are maintenance-free. Dry air is continuously supplied to the facade’s intermediate space, which allows pressure relief and forestalls condensation on the outer pane when the temperature fluctuates. The inner surfaces of the glazing do not soil and do not require cleaning – which reduces maintenance costs. By using daylight-optimised glazing and steering clear of dark sun-protection coatings, the project team created a facade with a high degree of transparency. Placing the solar protection in the facade’s protected intermediate space ensures that the control systems are durable because their surfaces do not become soiled.
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