ARCHITECTURE-ZIMBABWE: Termites Inspire New Office Complex

By Mercedes Sayagues Reprint | | Print |

Mercedes Sayagues

HARARE, Jun 4 1996 (IPS) - The humble termite nest has inspired the architecture and ventilation system of Zimbabwe’s latest and largest office complex and shopping mall.

What does the 30 million U.S. dollar Eastgate complex have in common with a termite home? Both structures use a unique system of natural air conditioning, based on air flows and the building’s own mass, to maintain a temperate climate inside, all year round.

Zimbabwean architect Mick Pearce has long been fascinated with termitariums. “It’s the perfect building, it responds to natural forces and doesn’t need mechanical energy,” he says. “Termites use every trick available to turn natural phenomenons to their advantage.”

By opening and closing tunnels or ventilation shafts, and taking advantage of heat-keeping earth walls, termites maintain an average temperature in their nest. This principle was also used by humans in cave dwellings in the Middle East, North Africa and Spain, and in some medieval castles.

Pearce applied it to the Eastgate complex in Harare — the world’s first large-scale commercial application of this energy- saving, environmentally-friendly ventilation principle.

The client, Old Mutual Properties, asked Pearce for a building that didn’t use expensive air conditioning, that would cool itself by passive means, using a technology appropriate to Zimbabwe. Using computer simulated heat gains, air flows and cooling, the London-based engineering firm Ove Arup designed Eastgate’s alternative ventilation system.

Basically, fresh air is pulled in by rows of big fans 10 meters above street level, and exhaust air is pulled out by 48 thick brick chimneys, without being recirculated. In the summer, cool night air is pulled in, and in the winter, warm afternoon air heats the building.

The air is changed twice per hour during the day and seven times per hour at night, using larger fans to speed cooling.

This system consumes only five percent of the energy a conventional air conditioning system would, while guaranteeing users a comfortable daily temperature all year round — not the uniform 20 C offered by air conditioning, but hovering between 18 and 25 C, according to the season.

That users should wear lighter or warmer clothes is a small price to pay for the substantial energy savings achieved in drought-prone Zimbabwe, dependent on hydroelectric power.

Compared with high-energy, imported, expensive air conditioning systems, this design has a capital cost eight-times lower and a peak electrical demand, in the hottest period, 20-times lower.

Because Eastgate was cheaper to build and to service, it can charge lower rentals. Shops and offices were rented before completion, and users seem happy.

“The whole building is a fun place to be, it’s like a community within Harare,” says manager George Mills.

Eastgate comprises two narrow office blocks, 140 meters long and 70 meters wide, with a covered atrium with shops in between, totalling 26,000 square meters of office space, 5,600 square meters of shops and parking places for 450 cars.

City regulations would have allowed a 28-story tower on the site but Pearce preferred a squat, massive nine-story building.

“We were trying to get away from the tower – such a masculine, militant, fortress-like object that doesn’t invite people in,” he says. “This is a much friendlier, open building.”

Pearce believes the days of the glass tower are numbered – or in each case they should be, as they are expensive to build, service and maintain, while adding little to the urban environment except an impressive skyline.

“Has any architect measured the effects on the biosphere of yet another mirror-glass clad tower block, or the effects of back radiation, or gas emission of air conditioning systems, or its energy consumption?,” he asks.

In style, Pearce draws inspiration from Victorian industrial architecture and from the Great Zimbabwe ruins, the spectacular 12th century walled remains of the capital of the Monomotapa empire in southern Zimbabwe.

“I have always been fascinated by the use of stone, of heavy, massive construction, and this building certainly reflects that,” he says.

Inside Eastgate, the friendly design, in pale green and cream colors, plays airily with transparent lifts and a glass-covered skywalk hung by cables suspended from lattice steel beams. The visible steel structure is softened by brick and granite-looking brushed concrete.

Outside, the building’s massive squat shape is enlivened by decorative patterns. To Pearce’s surprise, at the Africa ’95 exhibition of African culture in London, he found an identical pattern on an antique Shona headrest. “It’s a uniquely Zimbabwean building, it couldn’t have been built anywhere else,” he says.