The Powerhouse acknowledges the Traditional Custodians of the ancestral homelands upon which our museums are situated. We respect their Elders, past, present and future and recognise their continuous connection to Country.
2003/34/1 Models (4), Sydney Opera House, wood, designed by Jorn Utzon / made by Ove Arup and Partners, England / Australia, 1960-1968. Click to enlarge.

Models relating to the Sydney Opera House

These four models of the Sydney Opera House focuss on the work of, and relationship between, Over Arup and Partners the chief structural engineers for the Sydney Opera House, Jorn Utzon, architect for the Sydney Opera House and his successors Hall, Todd, Littlemore, architects. The collection as a whole also demonstrates the crucial role of modelling in architectural and engineering design.

The 'wind model' of the Opera House was used in studies by Ove Arup, which were concerned with …


Object No.


Object Statement

Models (4), Sydney Opera House, wood, designed by Jorn Utzon / made by Ove Arup and Partners, England / Australia, 1960-1968

Physical Description

Four models related to the Sydney Opera House:

One model, light brown timber, illustrating the 'Origin of the Roof Geometry of the Sydney Opera House'. Presented by Ove Arup and Partners, 1961-1965. Spherical model in sections.

One model, grey painted timber, of roof section profile, depicting the 'building sections' of the roof-line curvature for the 'shell' roof of the Opera House. The individual blocks are skewed to form a whole section.

One model, grey painted timber, of roof shell profile for the Sydney Opera House. Model is curved and triangular shaped. One side is smooth, the obverse has 6 rows of rib structures.

One model, polished timber, is a 'wind tunnel test' model Sydney Opera House (Major Hall), built to indicate wind pressure distribution over the roof sails. 1960.




Arup & Associates is an international engineering firm based in London. Arup has offices in eighty countries and its engineers have been part of several thousand large projects worldwide. Arup was founded by Danish engineer Ove Nyquist Arup (1885-1988) who established his reputation with Highpoint, Berthold Lubetkin's pioneering London apartment tower (1935). Arup's work on the Sydney Opera House project added further lustre and boosted the firm's expansion. Arup's engineers have worked closely with numerous notable architects.

Jorn Oberg Utzon (1918-2008) was born at Alborg, Denmark. His father was a naval architect, however Jorn Utzon's poor showing in class work and formal examinations (particularly in mathematics), excluded him from attending the polytechnic high school where he hoped to study, and follow his father in naval architecture. Instead he studied architecture and urban planning at the Royal Danish Institute of Fine Arts.

Prior to his work on the Sydney Opera House, Jorn Utzon designed several houses and housing estates and was placed highly in many architectural competitions for projects throughout Scandinavia and elsewhere. However he was almost unknown outside of Scandinavia.

The architectural design for the Opera House was settled by international competition. The number of entrants was huge, exceeding all expectations. By March, 1956, 881 competitors had registered. The closing date for reception of schemes was 3 December, 1956, and at this date, 231 entries had been received by the four judges. The competition winner was announced by J.J. Cahill (1891-1959), Premier of New South Wales, at a ceremony in the Art Gallery of New South Wales on 29 January, 1957. The Premier announced that Scheme number 218 had won the competition for the architectural design of the Sydney Opera House. Jorn Utzon of Denmark was entrant number 218.

Utzon left the project, controversially, in February 1966 after several disagreements with the newly-elected NSW government of Robert Askin and its Minister for Public Works, Davis Hughes. In Opposition, Askin had promised to control the costs of the Opera House project. At this time the structure and exterior of the Opera House were substantially complete.

There is no doubt that the early budget estimates for the Sydney Opera House were unrealistically low, but Utzon was widely and unfairly blamed for the project's spiralling cost. As a result he struggled to attract new commissions appropriate to his abilities and new-found fame. Among the few highlights of Utzon's post-Opera House career are the National Assembly of Kuwait and the Bagsvaerd Church, Denmark. However the Sydney Opera House holds a secure place as one of the outstanding buildings of the world, while its architect is similarly esteemed.

Desmond Barrett, Curator, Engineering Design and Charles Pickett, Curator, Design and built environment.



The drawings were used in the London and Sydney offices of Ove Arup and Partners, the wind-test model was used at Southampton University and the National Physical Laboratory (England), the sphere, rib, and segment models were used by Arup engineers in Australia.

There was no prior ownership of these items. They were developed by Ove Arup and Partners, Jorn Utzon, and Hall, Todd and Littlemore, at various stages of the project.

The architect's competition scheme for the roof was that of four main pairs of surfaces for the Major Hall. The proposals for the Minor Hall varied slightly. Each surface was a triangle in elevation, with boundaries formed by curves in space geometrically undefined. In cross-section, a pair of surfaces (or shells) formed a gothic arch. The main shells were connected to each other by a further series of surfaces termed 'side shells', also geometrically undefined.

The terminology used to describe the roof structure has grown with its development but is, strictly speaking, misleading. The term 'shell' stemmed from early hopes that membrane action would suffice to support the roof structure.

The structural implications of Utzon's design were first discussed with him at the first interview after he had won the competition. There were difficulties with Utzon's design that had to be resolved, thus forging a close collaboration between architect and engineer. The chief difficulties, as perceived by Ove Arup and G. J (Jack) Zunz, a senior partner in Over Arup and Partners, London, were:
(1) The interplay of surfaces made an assessment of structural feasibility by normal approximations difficult and of dubious value,
(2) The scale of the structure was misleading. The size of the site and the scale of the harbour and the bridge tended to diminish the building's apparent dimensions,
(3) Not only were the roof shapes geometrically undefined, but external and internal finishes had yet to be chosen, the auditoria ceilings and their acoustic requirements had not been formulated nor were the size and details of the stages and machinery available.

Several solutions to these difficulties were examined in the early stages of the collaboration between Utzon and Arup. Some ideas 'floated' then were the use of non-pointed arches, doubly curved shells covering each hall, and a single roof without discontinuities over both halls. These solutions were regarded as simple structural forms, and crucially, the solutions were meant to eliminate some of the large bending moments inherent in Utzon's roof shapes.

As said, the roof was initially determined by architectural, rather than engineering considerations. It was apparent early in the project, that any major engineering deviation from Utzon's proposal would destroy the sculptural quality of his design. Nevertheless, there was a firm commitment from Arup to finding a structural solution that would retain the roof profile and silhouttes initially conceived by Utzon.

A two-phased programme of architectural and engineering designs for the roof occurred between 1957 and 1963. The first phase was from 1957 to 1961, and the second was from 1961 to 1963. In the first phase, an enormous amount of analytical work and 'model tests' were directed towards finding a solution to the 'roof problem'. In structural engineering terms, the problems to be solved were:
(1) A geometric discipline had to be imposed on the surfaces in a way which would provide adequate clearances for the stage towers, balconies and auditoria roofs, all of which were unknown in any detail (refer to spherical model of roof).
(2) The roof structure had to be proved stable under all possible loads and without undue distortion under normal conditions.(3) The wind loads on the curved surface were unknown and had to be established by wind tunnel tests (refer to large timber model of the Major Hall, Opera House).
(4) A construction method had to be evolved having regard to structure, cladding (tiles) and the variable geometry of any staging system.

It was clear in these early days that to achieve a solution, to make it possible to build the structure, extensive use of electronic digital computers were necessary, to cope with the massive number of geometric problems and the complexity of the analytical work. Utzon was not opposed to geometric discipline. Early geometric systems embodied a system of parabolas and this greatly improved the appearance compared with the original free shapes of the roof. Crucially, the introduction of a geometric discipline, gradually rationalized the design and construction of the entire project, and made possible the factory production of geometrically similar elements.

The second phase, from 1961 to 1963, saw the design of the roof and associated analyses shift from an ellipsoid scheme to a final spherical scheme.

Des Barrett, Curator, Engineering Design.


Credit Line

Gift of Ove Arup and Partners, 2003

Acquisition Date

26 February 2003

Cite this Object


Models relating to the Sydney Opera House 2022, Museum of Applied Arts & Sciences, accessed 3 December 2022, <>


{{cite web |url= |title=Models relating to the Sydney Opera House |author=Museum of Applied Arts & Sciences |access-date=3 December 2022 |publisher=Museum of Applied Arts & Sciences, Australia}}