Finding termites building huge mounds in rural areas seems to be acceptable. A seven storey building in the centre of a busy city, inspired by termite architecture, would seem to be impossible. Yet that is exactly what the builders of the Eastgate Mall have accomplished.
The Eastgate Mall, a shopping centre and office block located in one of the busiest central business districts of Harare, is one huge modern termite mound. It was designed to be ventilated and cooled by entirely natural means. The Eastgate Mall is one of the first modern high rise buildings in the world to use natural cooling and ventilation at this level of sophistication. Situated along Robert Mugabe Avenue between Second and Third Streets, the building is seven storeys high and provides 5,600m2 of retail space, 26,000m2 of office space and parking for 450 cars. Construction began in 1992 and it was officially opened in 1996.
The design of the Eastgate Mall was inspired in part by indigenous Zimbabwe masonry, like that found at Great Zimbabwe, and the self cooling mounds of African termites (Odonto termes or Transvaal emsis). It utilizes less than 10% of the energy of a conventional building of its size.
Mick Pearce, the architect of the building, says he has always been fascinated by the Great Zimbabwe Ruins. He has taken design inspiration from the ingenuity of the builders of Great Zimbabwe and combined it with some lessons learned from the humble termite. “Termites create a very well organised community. Their building acumen is outstanding. Compare the way they build and the way we build. The former is absolutely in harmony with Nature,” he explains.
The termites build mounds that have a chimney at the top which opens to the outside. This arrangement creates induced flow which is called the stack effect. The chimney breaks the surface boundary layer and is exposed to higher wind speeds compared to inlets on the ground. The uni-directional flow draws fresh, cool air from near the ground level into the mound, from where it passes on through the chimney and ultimately up to the outside.
The building incorporated this termite technology. It has an extensive tube system within the walls and floors that moves air through the building, along with stored heat within the structure. This creates a ‘thermo siphon’ or heat siphon effect that draws air up and through to the rooftops where large chimney stacks are located. These tall stacks are essential for creating an induced air current.
Comparisons made by Ove Arup, the engineers of the building, show that the energy consumption of Eastgate is minimal compared to other office buildings in Harare.
Mick Pearce was born in 1938 in Zimbabwe. He went to school in Ruzawi in Marondera then to Bishops in Cape Town, South Africa. He received his diploma with distinction at the Architectural Association School of Architecture in London in 1962. He has designed several buildings in Harare, among them Anchor House, Old Mutual Centre, the Batanai Gardens, Hurudza, 101 Nkamwe Nkruma, Chinoyi Hospital and the Nkulumane Shopping Centre in Bulawayo.
Committed to appropriate and responsible architecture, Pearce has
specialised in designing buildings that have low maintenance and running costs, low capital expenditure and utilise renewable energy systems for internal environmental control. He has been closely involved in the development of rammed earth construction for low cost housing in remote parts of Zimbabwe where transport and energy are the biggest costs in producing buildings. His projects try to make the best use of locally available resources.
In 2003, Pearce was awarded the Prince Claus Award for Culture and Development for his work on the Eastgate Mall. He is also a member of Architects for Peace.
Photo: Graham van de Ruit