> H ARARE, Zimbabwe -- Africa owes its termite mounds a lot.
> Prospectors mine them, looking for specks of gold carried up from
> hundreds of feet below. Africans building mud huts love them,
> because the grainy soil inside is just the right consistency for
> hard-packed floors. And of course, to aardvarks and other
> insectivores they are giant helpings of baked alaska.
>
> Now, Africa is paying an offbeat tribute to these ugly towers of
> bug-holed mud. Harare's newest office complex is said to be the only
> one in the world to use the same cooling and heating principles as
> the termite mound.
>
> That's no mean feat. Termite mounds are marvels of engineering. Deep
> inside, the insects farm a fungus, their only food. It must be kept
> at exactly 87 degrees, while the temperatures on the African veld
> outside range from 35 degrees at night to 104 degrees during the
> day.
>
> They do it by venting breezes in at the base of the mound, down into
> chambers cooled by wet mud carried up from water tables far below,
> and up through a flue to the peak. Toiling with the tireless,
> compulsive work ethic of all ants, they constantly dig new vents and
> plug old ones to regulate the temperature.
>
> Temperature regulation is a struggle familiar to any architect. Mick
> Pearce of the Pearce Partnership was given a challenge by Old
> Mutual, an insurance and real estate conglomerate: build an office
> block that would be livable with no air-conditioning and almost no
> heating.
>
> Eastgate, the result, has been open for only nine months, but so far
> Pearce seems to be succeeding: the complex has been using less than
> 10 percent of the energy of a conventional building its size. Old
> Mutual saved $3.5 million on a $36 million building because an
> air-conditioning plant didn't have to be imported. More important,
> the savings on electricity are passed along to tenants, so rents are
> 20 percent lower than in a new building next door.
>
> The complex is actually two buildings linked by bridges across a
> shady, glass-roofed atrium open to the breezes. 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
> it rises and warms, it is drawn out through ceiling vents. Finally,
> it exits through 48 round brick chimneys that make the roof look to
> some like the chimney pots of Dickensian London and to others like
> the smokestacks of the Queen Mary.
>
> To keep the harsh highveld sun from heating the interior, no more
> than 25 percent of the outside is glass, and all the windows are
> screened by an unusual form of sunshade: racks of cement arches that
> jut out more than a yard.
>
> During summer's cool nights, big fans flush air through the building
> seven times an hour to chill the hollow floors. By day, smaller fans
> blow two changes of air an hour through the building, taking
> advantage of what Pearce calls "the coolth in the slab." For winter
> days, there are small heaters in the vents.
>
> This is all possible only because Harare is 5,400 feet above sea
> level, has cloudless skies, little humidity and wide temperature
> swings -- days as warm as 88 degrees commonly drop to 58 degrees at
> night.
>
> "You couldn't do this in New York, with its fantastically hot
> summers and fantastically cold winters," Pearce said. But then his
> eyes lit up at the challenge. "Perhaps you could store the summer's
> heat in water somehow ..."
>
> The engineering firm of Ove Arup & Partners, which worked with him
> on the design, monitors daily temperatures outside, under the floors
> and at knee, desk and ceiling level. "This isn't all dancing around
> in the moonlight," Pearce said. "It's real science."
>
> Ove Arup's graphs show that the building has generally fluctuated
> between 73 and 77 degrees, with the exception of the annual hot
> spell just before the summer rains in October (the seasons are
> reversed in the Southern Hemisphere) and of three days in November,
> when a janitor switched off the fans at night. The atrium, which
> funnels the winds through, can be much cooler.
>
> "It's only about three weeks of the year we get complaints," Pearce
> said. "The rest of the year is fine." Turning on the fans later at
> night during hot spells seems to help.
>
> Tenants confirmed that.
>
> "It was absolutely too hot in October," said Debbi Hawkins, who
> designed IBM Zimbabwe's offices in the building. "We all ended up
> opening our windows. Now, it's absolutely fine. I do find it a
> little stuffy. I'm not too keen on air-conditioning, but I like
> fresh air from outside."
>
> The air is fresh, Pearce said -- far more so than in air-conditioned
> buildings, which recycle up to 30 percent of theirs. It just enters
> unobtrusively, through vents at ankle height.
>
> As far as beauty goes, Eastgate, more than most buildings, has a lot
> of function for form to follow. True to the idea of a termite mound,
> the first word that comes to mind is "busy" -- inside and out.
> Pearce, disdaining smooth glass skins as "igloos in the Sahara,"
> calls his building "spiky." While other buildings that expose their
> girders and pipes seem to be built of Erector sets, Eastgate looks
> like Lego.
>
> Other elements tumble over the viewer: the signature "tiaras" over
> the entrances are meant to resemble the porcupine-quill headdresses
> of the local Shona tribe, but to non-Shonas they look like the
> innards of supermarket bread-slicing machines. Elevators were
> designed to look like mine-shaft cages; their controls resemble ship
> binnacles. The fan covers, chevrons in granite, are echoes of Great
> Zimbabwe, the ruins that give the country its name.
>
> The deluge of designs "is one of my problems -- I'm a bit Gothic"
> Pearce admitted.
>
> Standing on a roof catwalk, peering down inside at people as small
> as termites below, he said he hoped the plants would grow wild and
> pigeons and bats would move into the atrium, tempering the whole
> "natural machine" metaphor with a bit more nature -- like that
> termite fungus. "But," he confided, with a bounce of his eyebrows,
> "the client hates it when I talk like that."
Hal Levin <hlevin@cruzio.com>
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