Photos: D. Di Bello/ T. Nicolini/ G. Basilico
It was once regarded as the ‘beating heart’ of the original Pirelli factory..
Gregotti Associates International’s project for the Pirelli Groups New Head Office, is developed from the old high rise cooling tower, the only witness left from the old manufacturing practices on this quarter of the city..
The north and south elevations host the offices, combined with open circulation areas, and are fully glazed on the sides which face the internal courtyard and towards the cooling tower, whilst the east elevation contains the stairwells and plantroom areas..
The large fully glazed façade on the west elevation, on one hand presents the tower as a precious exhibit on display, and on the other opens the whole building towards the monumental ‘Villa Della Bicocca Degli Arcimboldi’ and onward towards the centre of Milan..
The exterior has a predominance of ceramic stone cladding; special tiles designed for this project were inserted into a series of horizontal supports consisting of bespoke aluminium profiles completed by an external profile clip similar to a traditional glazed façade. This solution was extremely individual, when compared with a traditional ventilated façade, providing a regularity in the design which alternates with the ribbon windows. The windows are attached to a primary steel structure and are formed from aluminium frames with a thermal break. There are bow windows and a glazed façade which is constructed from a series of extruded aluminium mullions and transoms forming a grid which contains double glazed panels, there is an external aluminium profile which is attached to the mullion and transom grid and retains the glazed panels in place..
Crowning the upper perimeter and the roof of the building there is a zone of glass blocks that depict this area with an evanescence and translucency, blending the building into the horizon. This envelope of glazing results from an extremely original architectural solution combining transparency and light diffusion. Glass blocks with a length and height of 200mm, have been utilised here, and are assembled in specially formed galvanised steel frames, the blocks are mortared together and silicone has been used to ensure the impermeability of the finished panels..
The complexity of this project with its bespoke façade systems and the short time available - one year to design and build - turned out to be a real challenge to which the whole company replied with the maximum effort thus reaching the goals of a completed building and a satisfied client.
A complex and lengthy study was carried to harmonize the façades types which are identical in an aesthetic view point, but very different in their performance characteristics..
The façades consists of a galvanized steel structure with a ceramic stone cladding (bespoke tiles 747 mm x 1.230 mm) and some windows with thermal break aluminium frames..
The tiles have an ornamental horizontal aluminium strip, which allows the incorporation of aluminium sunshading for the windows..
The whole system provides a thermal insulation ratio of Uw = 0,78 W/m2K (UNI 10346) and an acoustic insulation of Rw = 39 dB which has been certified (ISO 140/3 e ISO 717/1).
The stairwell cladding have a fully ventilated cladding, it connects with the windows and doors inserted in the openings of the traditional masonry. There is a transformation on the lower part of the building where the horizontal aluminium profiles supporting the stone tiles are replaced by Focchi’s “Sicof” concealed fixing system, allowing unbroken strips of tiling.
INTERNAL COURTYARD CURTAIN WALLING (QUADRA 4.500 m2) Traditional stick curtain walling with uninterrupted bespoke aluminium spandrel panels at floor slabs. The concealed fixing system of the façade allows a movement ± 2 cms at floor slabs due to excess loads. .
SUSPENDED BOLTED FAÇADE, FITTED WITH UPPER GLASS BLOCKS (WEST ELEVATION 2500 m2)..
The west elevation of Pirelli Headquarter with its suspended bolted façade represents one of the main architectural landmarks in Italy due to its technology and size.
The whole system is suspended from a steel beam with a single span 40 m in length. In addition the steel structure of the façade consists of 11 laser cut tubular beams (diameter 150 mm) set horizontally. Each one is circa 40 m long and 2,5 m deep, these are anchored similarly to upper beam and remain suspended by means of tubes 100 mm diameter at 3 metre centres, alternating with 60 mm diameter tubes also at 3 m centres. .
The steelwork was cut using lasers with a maximum tolerance ± 0.2 mm, and welded using robotic technology. This use of the most up to date industrial methods meant the maximum deviation tolerance would be ± 0.5 mm..
Even though not specifically requested by the Design Team, the welding was subjected to non destructive testing..
All steelwork has been sandblasted and has a received a coating of oven baked paint. fixings and ‘spider’ clamps for the glazing are in stainless steel. The load bearing steel beam has been pre-stressed to ensure that it has a zero deflection when supporting the glazing. To allow glazing installation the glass load had to be simulated by use of a threaded rod attached to every mullion which could be regulated as installation progressed to ensure an even loading.
The average size of the glazed modules is 1500mm x 3840mm. The glazing is laminated with an external sheet 12mm thick, toughened with Heat Soak Test, laminated to an 8mm heat strengthened inner pane, it is fixed to the structure by 6 no. ‘spider’ fittings. This system was thoroughly tested to ensure that if the glass broke, and there was a wind blowing, glass fragments would not fall causing a hazard to persons below (the height of the façade is 40m). The total glass thickness is circa 20mm, to ensure the best possible transparency ‘Low Iron’ glass was used to form the laminated panes.
Gregotti Associati International architects
Vittorio Gregotti was born in Novara in 1927 and he graduated in architecture at the University Politecnico di Milano in 1952. From 1953 to 1968 he carried out his activities in collaboration with Ludovico Meneghetti and Giotto Stoppino. In 1974 he has founded the practice Gregotti Associati, which he is president. He was a professor of Architectural Composition at the Institute of Architecture University in Venice, he taught at the Faculty of Architecture of Milan and Palermo, and was visiting professor at the University of Tokyo, Buenos Aires, Sao Paulo, Lausanne, Harvard, Philadelphia, Princeton, Cambridge (UK) and M.I.T. Cambridge (Massachusetts.). He has participated in several international exhibitions and has been responsible for the introductory section of the XIII Triennale (Milan 1964), for which she won the International Award. From 1974 to 1976 he was director of visual arts and architecture of the Venice Biennale. He is Academic St. Luke from 1976 and the Brera Academy from 1995. He was awarded an honorary degree from the Technical University in Prague in 1996 and the Faculty of Architecture of the Polytechnic of Bucharest in 1999. Since 1997 he is a member of the BDA (Bund der deutschen Architekten) and since 1999 he is an honorary member of the American Institute of Architects. From 1953 to 1955 he was editor of Casabella, from 1955 to 1963 editor of Casabella-Continuity; from 1963 to 1965 Director of Edilizia Moderna and responsible for the architecture section of the magazine Il Verri; from 1979 to 1998 he was Director of Rassegna and from 1982 to 1996 again Director of Casabella. From 1992 to 1997 he collaborated with the BBC since 1997 and works with the main Italian newspapers La Repubblica and Il Corriere della Sera.