The Calyx

About the Entry

Sustainability, flexibility and inspiration underpins the design of the Calyx. This landmark project, designed by PTW Architects in celebration of the Royal Botanic Garden’s 200th Birthday, was conceived as a ‘jewel in the Garden’: a serene and peaceful arbour pavilion with the capacity for ever changing requirements when displaying plants.

Features & Benefits

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A Jewel in the Garden

Set at the edge of the Royal Botanic Garden between the Domain and the City of Sydney, the architectural concept for the Calyx was to create a ‘jewel in Garden’, an iconic and serene, ‘peaceful’ building with the capacity to adapt to ever changing horticultural displays. As well as performing simultaneous roles which address formal uses the Calyx as a ‘jewel’ inspires a timelessness befitting a public building within an historic landscape of public interest and national importance.

Flexible functional spaces

To fulfil the Garden’s mission for science and education, innovation is achieved through an understated yet flexible sequence of spaces that can be used for horticultural, educational or cultural purposes as well as event and lecture spaces. The deliberate arrangement of spaces within the floor plan recognises this potential and to optimise effective lighting and efficient mechanical services. Retractable walls allow for a changeable building section and flexibility of space. By maximising flexible usage of the minimal physical fabric the quantity of elements requiring water and energy consumption during construction and long term usage is reduced.

Respecting the Arc

The Calyx in its design concept and execution respects its setting on the site of the Tropical Centre, the former 1972 pyramid glasshouse designed by the NSW Government Architect Office. It also sensitively integrates with the existing 1988 Arc Glasshouse designed by Ancher Mortlock and Woolley. Its elegant stainless steel structure was retained and a four metre high space excavated under the structure to create a cathedral like exhibition gallery. An offset in room heights enables low level winter sun to penetrate the ‘Arc’. At the entry level a circular arbor of steel portal frames intersects with the existing geometry of the ‘Arc’, which it turn, is generated from the centre of the former pyramid glasshouse.

The Arbour

A delicate circular arbour of prefinished steel portal frames spatially define a jewel in the Garden. Integrated with the entry plaza the external portion of this frame was designed with the capacity of becoming a flexible outdoor horticultural display and/or venue space. As a central component of the design the arbour is configured to provide a memorable identity for the project in harmony with the Royal Botanic Gardens.

The Iris

The central ‘Iris’ garden of the Calyx is a focal and public point of the radiating arbour. Visitors can freely amble around the garden enjoying the ambience of the arbour. A flexible setting, open to the sky, it provides opportunity for changing outdoor horticultural exhibitions that complement those of the Calyx interior.

Key Sustainability Design Features and Benefits

PTW worked closely with the client, builder and consultants to evolve, co-ordinate and deliver design and construction decisions directed to maximising life cycle sustainability and efficiencies.

The team significantly reduced the environmental impact and usage of embodied energy, materials and water in the project by retaining the existing ‘Arc’ structure which contributed approximately one third of the project’s built volume. Rather than excavating a larger building footprint, the space below the retained structure was used, which preserved the surrounding landscape. A hybrid, glazed system takes advantage of natural ventilation, shading and mechanical intervention for a variety of environmental conditions.

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The Calyx