Unilever Indonsa Plant- Riverhorse Valley, Durban
‘Industrial art’ is how Unilever’s new dry food production and warehouse building in Riverhorse Valley has been described. The brief was to create ‘a landmark, global flagship and state-of-the-art production facility that is sustainable, energy-efficient and a world-class iconic building’. The development includes a research development facility and offices integrated into the savoury dry food plant. The design concept is a formal metaphor in abstract reference to the conveyor production lines which are integral to the core functions of the factory. One of the key elements of the design was to disengage the offices from the main warehouse which allowed this element to be expressed individually, while still maintaining a consistent design language. A concordant architectural language was the key design principle and is displayed at a variety of scales in the complex – from the production space to the joinery in the offices. The varying heights of the factory roof are in direct response to the volumetric requirements in the factory. The various raised roofs are expressive of the mechanical processes inside the factory. The offices are characterised by the image of two interlocking conveyor belts and the combination of these elements results in an iconic form that exemplifies the design concept. The machine-like formal quality exhibited in the building is then amplified in the detail resolution of the building envelope. A fundamental aspect in the design solution was that the complex embodied sustainable principles in respect of water usage, air treatment, reduction of thermal gain, maximized use of natural light and in the deployment of materials.
Water and carbon dioxide
At the time of the project’s inception, product demand outstripped supply, so Unilever’s priority was to increase supply, while reducing the carbon footprint. As a result, the project is the first plant globally to be completely water neutral and this is achieved by using the 22 000m2 roof to harvest rainwater in storage in a millionlitre subterranean water tank. Water efficiency technology facilitates reuse of 70% of the water used in the production process and grey water is recycled to drinking water quality using biological and reverse osmosis treatment. The harvested rainwater, recovered air-conditioning condensate and grey water are treated separately and fed back to the domestic water storage tank to be reused, ensuring that there is continuous supply of water for production.Through design optimisation, use of alternative non CO2-releasing energy sources and purchasing Carbon Emission Reductions or carbon offsets through certified schemes, the development has managed to get as close to carbon neutral as possible. The new development facilitates doubling the production volume of the original factories, whilst reducing the energy consumption by 60%. This can be translated as a saving of 26 800 MWh per year, equivalent to 1 970 households in South Africa.
Heat and light
A variety of embodied energy reductions was deployed, including the use of aluminium roof sheeting and sunscreens in place of steel. The factory roof structure was designed as a deep vertical truss system which significantly reduced the steel mass and the use of polycarbonate and fixed louvres was employed to promote diffused natural light and ventilation in the warehouse. In the offices, performance glass and fixed sunscreen louvres that specifically respond to each façade orientation, preeliminate the ingress of direct sun, while maximising natural daylight. The performance aspects of the external skin of the factory have been matched directly with the functional requirements of each component of the factory. Storage areas are naturally ventilated through fixed louvres, with the roof insulated to achieve a U-value of 0,43W/m2K. The manufacturing zone and the packaging hall is air conditioned, smoke ventilation is through motorised louvres and the roof and cladding is insulated to achieve a U-value of 0,43W/m2K and 0,37W/m2K respectively. The packaging hall is the most highly populated area and it was an expressed desire to provide natural light and views to this area as no glass is permitted in the plant. A window wall of single and double-wall polycarbonate was incorporated in the north-west façade and includes perforated aluminium louvres and solar shells to afford shading to the entire element. There are no geysers in the building; instead one of the HVAC chillers incorporates a heat-recovery system. Heat extracted from the factory space by the air-conditioning system is transferred to the water in the hot water plant by a heat exchanger. The design of the HVAC system was based on a high-efficiency sustainable design solution with an air-cooled water plant selected over water-cooled chillers to reduce water requirements. A portion of the facility required humidity control, which requires over-cooling and then reheating air to remove moisture. This heating is provided by the heat-recovery chillers with no additional energy requirement. External air introduced into the plant is provided through energy-recovery wheels, which provide free pre-cooling of the generally hot and humid ambient air, resulting in a significant reduction in energy usage. All ducting is manufactured from a recyclable fabric, which is also demountable for regular washing for hygienic purposes.
Waste and landfill
All solid waste from the plant is separated on site and sent off for recycling, and not to landfill sites. Organic product waste is directed to those needy communities in the area that have compost heaps and gardens.
The selection of materials prioritized low-maintenance materials that promote sustainability and a reduced carbon footprint. The warehouse comprises off-shutter, reinforced concrete combined with face brick infill, and recyclable aluminium roof sheeting and cladding. Local face brick was utilised to reduce the transportation impact. Concrete with high-fly ash content was selected and steel with a high-recycled content was specified. The columns to the warehouse act as a composite structure. The steel vertical trusses providing the warehouse with its raking cladding are used as tensile elements to provide the wind bracing to the concrete columns which act purely in compression. No timber or glass elements could be incorporated into areas for food production and packaging and consequently only aluminium and polycarbonate were used in these areas. The south-west wall of the packaging hall features an anchor wall of natural light. This comprises ribbed doublewall polycarbonate glazing, providing high insulation values, combined with clear solid polycarbonate panels to provide views for the most populated production area.The office component deploys offshutter reinforced concrete as a primary material with aluminium framed high performance glass. The low transmission glazing to the offices and the polycarbonate glazing to the factory are protected from direct sun by a combination of aluminium solar shelves and perforated aluminium vertical louvres to reduce solar exposure and thermal gain.
The design process has been one which required a continual questioning of the norms for this building type. The broad concept for the building and its main spatial features were developed out of an intention to represent something of the factory process it housed. It has been adapted by a careful filtering through rigorous determinants of a high level of water neutrality and substantially reduced embodied energy levels and has been honed by the use of low-maintenance, low-carbon footprint materials. The result is what the jury in the SAIA Award of Merit programme described as ‘a fine and very sophisticated building, rationally conceived, impeccably detailed and engaging, which expresses with great clarity the briefed requirements. It demonstrates a thoroughly integrated brace of environmental control to minimise energy usage while maximising user comfort, including the penetration of natural light into all space.’ They also made the point that an excellent relationship had been achieved between architect and client, with the latter naming the building Idonsa (meaning ‘rising star’ in Zulu).
- This building received a 2013 Award of Merit from the KwaZulu-Natal Institute of Architects.