The extraordinary Eastgate Building in Harare, Zimbabwe's capital city, is said to be the only one in the world to use the same cooling and heating principles as the termite mound . Architect Mick Pearce used precisely the same strategy when designing the Eastgate Building, which has no air-conditioning and almost no heating. The building--the country's largest commercial and shopping complex--uses less than 10% of the energy of a conventional building of its size. The Eastgate's owners saved $3.5 million on a $36 million building because an air-conditioning equipment didn't have to be imported. The complex is actually two buildings linked by bridges across a shady, glass-roofed atrium  open to the air. Fans suck fresh air in from the atrium, blow it upstairs through hollow spaces under the floors and from there into each office through baseboard vents . As _ rises and warms, it is drawn out via ceiling vents and finally exists through forty-eight brick chimneys. During summer's cool nights, big fans blow air through the building seven times an hour to cool the empty floors. By day, smaller fans blow two changes of air an hour through the building, to circulate the air which has been in contact with the cool floors. For winter days, there are small heaters in the vents. This is all possible only because Harare is 1600 feet above sea level, has cloudless skies, little dampness and rapid temperature changes--days as warm as 31degC commonly drop to 14degC at night. "You couldn't do this in New York, with its hot summers and cold winters," Pearce said. The engineering firm of Ove Arup&Partners monitors daily temperatures. It is found that the temperature of the building has generally stayed between 23degC and 25degC, with the exception of the annual hot period just before the summer rains in October and three days in November, when a doorkeeper accidentally switched off the fans at night. And the air is fresh--far more so than in air-conditioned buildings, where up to 30% of the air is recycled. Why was Eastgate cheaper to be built than a conventional building?
It was designed in a smaller size. No air conditioners were fixed in. Its heating system was less advanced. It used rather different building materials.