Grain silo complex; Grain silo complex;

Grain Silo Complex, Cape Town

Reimagining a redundant industrial building into an iconic gallery

The Grain Silo was built in the 1920’s for export storage and at the time was the tallest building in Sub-Saharan Africa. The V&A Waterfront made the previously mothballed building its central feature of the newly rejuvenated Silo District

Working with the concept architect (Heatherwick Studios) Arup assisted with the redevelopment of the complex. Arup realised the structural and façade engineering behind the architect’s bold intention to carve a massive atrium into the existing silo bins. Externally, we realised the architect’s vision of glass facade ‘pillows’ inserted in to the existing geometry of the upper floors. These facade ‘pillows’ define the external character of the building and mirror the sky.

Arup provided full multidisciplinary input to feasibility, and were further appointed to deliver full façade, mechanical and public health engineering services. Our teams targeted wind, daylight and resilience studies at key stages during the design process. Along with climate control design to meet with strict international museum standards. 

Project Summary

70 unique triangular glass panes

3,518tonnes of concrete, glass and steel suspended above the atrium void

4,600m3carved atrium space

Unlocking the structure

Though the concrete building looks like a single structure, it has two parts: a grading tower and a storage annex of 42 cellular silos. Working with the concept architect we developed structural principles that were applied across the project. These principles can be summarised as ‘re-use or strengthen’ where possible, but also unashamedly ‘demolish and rebuild’ with new structures to enable the vision of a gallery and hotel. Resleeving the retained cylindrical silo bins with a layer of reinforced concrete held the old infrastructure in place, whilst at the same time creating a new building in and around the old.

The 4.9m diameter trafficable glazed skylights are fitted with bespoke artwork

Skylights that delight and engage

Arup designed publicly trafficable skylights to be inserted in the top of the 4.9m diameter silo bins. These skylights are laminated glass panels glazed to a steelwork support frame and then anchored to the concrete structure. The steelwork frame also doubles as a support for the surrounding pavers. The anti-slip top layer, executed in an abrasive silk screen print feature a bespoke artwork of symbols. The skylights form part of an external sculpture garden and are designed to support the loading from crowds and sculptures – allowing visitors to experience the grain-shaped atrium volume from a unique perspective.

Enabling the iconic glazed pillows

The most significant change to the buildings external appearance is the insertion of the iconic convex 'lantern' façade panels or ‘pillows’ into the existing structural frame. We realised the architectural vision by creating a model that allowed real-time iterations of the façade geometry, with each solution assessed for viability. This ensured that the complex design was achieved efficiently, providing a sound basis for procurement to reduce costs and programme risks

World class environmental control

Our team designed a two-stage environmental control system. A single system dedicated to filtering and purifying the outside air and multiple smaller systems dedicated to conditioning each gallery space. The atrium is naturally ventilated through a control system, while the galleries utilise a raised floor for air distribution to facilitate a low velocity displacement system. The galleries also make use of the thermal inertia from the exposed concrete soffits to help regulate the temperature and humidity in the spaces, slowing the rate of temperature change in the gallery spaces as visitors pass through.

A glowing lantern at the harbour edge

The architectural intent of the façades was for a transparent faceted glazed pillow, with slender framing elements. Technically however, the frame performs several roles. A steel framed pillow with double glazed solar control triangular panes bonded to aluminium glazing bars on outward facing steel frames. The faceted façade form maximises views and natural light while the increased reflection angles reduce peak energy loads when compared to a flat façade. Our mechanical engineers leveraged this to design for a lower peak condition, reducing the plant size and in turn the running costs.