Zeitz MOCAA

Zeitz MOCAA makes use of a disused grain silo complex and through the inventive use of concrete-cutting techniques as well as traditional craftsmanship has been adapted into a significant new home for a not-for-profit museum institution with a mission to provide economically viable access to contemporary art to the public. The upper portion of the silo complex also accommodates a new boutique hotel.

As a listed building complex that was originally built in 1921, we wanted to ensure that the transformation of the grain silo would still retain the spirit of its original industrial heritage and remain an iconic part of Cape Town’s harbour front.

From the outside, we chose to remove the thick layers of render and paint that had been applied to the silo’s façade to reveal the original concrete. The greatest visible change is the creation of new pillow-glazed windows, inserted into the existing geometry of the tower’s upper portion. By night, this transforms the building into a glowing lantern or beacon in the harbour.

The main challenge was to convert the original tightly packed concrete tubes into spaces for displaying art. Unlike many conversions of historic buildings which have spaces ready to be repurposed, this building had none. The project became about imagining an interior. We developed a concept to carve out an atrium, like a vaulted cathedral, to form the museum’s heart. Scooped from the building’s centre, it provides access to the gallery floors that are organised around the central atrium.

Decisions related to the adaptive re-use of the building were guided by a decision tree made up of a series of successive options; the first was to re-use. If this wasn’t possible, strengthen and re-use; then, duplicate but retain the original, and finally, selectively dismantle or demolish and build new. The intention was to retain as much of the original fabric as possible in order to preserve the authenticity.

Realising the concept of carved tubes was technically challenging. Modelled on a single grain of corn, the rounded shape was scaled up to fill the 27-metre high volume and translated into thousands of coordinates, each defining a point within the silo’s tubes. Mapped out physically with nails, the brittle concrete tubes 170mm thick were then lined with inner sleeves of reinforced concrete following the atrium shape.

The sleeved tubes together formed a gigantic arch spanning the future atrium space and provided a cutting guide for removing portions of the old silos with handheld double disk saws. The existing tubes were pared back to reveal the curved geometries of the 4,600 cubic metre atrium.

The atrium also revealed the tunnels that existed beneath the complex. These were made accessible to visitors along with new education spaces. Main circulation routes are housed within the atrium via cylindrical lifts that exist inside two bisected concrete tubes. The remaining internal tubes were removed to make space for 80 barrier-free gallery spaces.

We had to think carefully about sustainability and how it responds to the local context of South Africa. We installed a displacement ventilation air-conditioning system, maintaining the temperature and humidity of the galleries at much lower velocities and with narrower temperature bands than if the air needed to be forced from high-level down to cool (or heat) the spaces. Two levels of the museum have Class A climate control systems with the remainder, all Class B.

In addition to the large amounts of exposed concrete in the re-sleeved bins of the atrium, the space is naturally ventilated with warmer air rising and exhausted via openings at high level. The high thermal mass helps to regulate the indoor climate, keeping it within acceptable bounds. Most of the internal walls of the galleries are constructed out of drywall systems – a sustainable choice as gypsum is recyclable, with quick installation and no wet works required. These are also flexible for layouts to change in the future.

The district in which the building sits uses collective district-wide utilities. These include a sea water-cooling and heating plant that uses the ocean for renewable heat rejection, reducing the consumption of electricity and potable water required to heat and cool the buildings. Shared district generators provide back-up electricity, eliminating the need to install multiple smaller generators, improving spatial and operational efficiency.

Construction began on the R500 million (£30 million) project in 2014 with the museum opening in September 2017.

Ground floor plan

Section

Level 4

Level 6 - sculpture garden

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