Lattice wings.

The recent restoration of the horticultural gardens of the Parc Floral in Orleans included the construction of a new aviary to house and display the park's collection of birds. The natural splendour of the site meant that any new structure had to be introduced into the landscape with as little disturbance as possible. The swooping, tensile mesh structure, designed by RFR, provides a new focus on the principal axis of the park. The site is inscribed within a circle of 28m diameter astride a central path, which bisects the aviary structure into two symmetrical volumes. The main axis draws visitors through a central space, defined by earth banks that anchor the aviary to its site, creating the sensation of being surrounded by birds and reversing the traditional more formal relationship of zoo enclosures.

The 18m high masts permit glimpses of the structure from a distance among the surrounding trees. The inclined masts generate a strongly sculptural form, while the delicate, veil-like mesh gives the structure a light, ephemeral presence. Each 'wing' of the aviary is suspended from cable-stayed central masts. The symmetrical arrangement of the enclosures allows the mesh to stabilise the structure transversally by means of a cable linking the two masts.

The tensile enclosure is an interwoven crimp-mesh membrane, fabricated from 2mm diameter stainless steel wire woven on a 30mm x 30mm spacing. Since the mesh is not welded, it can be easily deformed to create three-dimensional forms in the same way as fabric. The membranes are effectively structurally efficient, avoiding the need for secondary structure elements and maximising transparency. The masts are positioned outside the aviary, so as not to inhibit the interior space for the birds.

Initial investigations of the structural form were conducted using small scale physical models. Progressively larger models were made, culminating in a representation at 1:50 scale of one half of the structure. This master model served to define the final geometry and the cutting pattern of the mesh and all subsequent drawings and calculations were based on it. A computer program devised for designing and calculating racing yacht sails was used to check the geometry and structural behaviour of the membranes. This unconventional working method proved useful in explaining the project to both client and contractor, who eventually used the master model on site as a reference during the construction process.

For such an unusual brief the challenge was to realise a large, uninterrupted volume using a minimum of material with maximum structural efficiency. Reducing the project to its essentials generates a legible relationship between form and structure that is both poetic and highly functional.