The December issue of Red: the Green Magazine is out in the Cape, and it features an article I wrote about alternatives to air conditioning, especially evaporative cooling. Here’s what it has to say:
Craig Bransgrove has been installing air conditioning in Cape Town homes and offices for the last six years. So it may seem surprising that when he recently installed a cooling system for his own home, he did not choose traditional air conditioning at all. Bransgrove’s Blouberg home uses an evaporative cooling system that takes advantage of the same effect that makes a wet swimming costume feel so chilly on a windy day. “I looked at all the options,” says Bransgrove. “It’s a lot healthier and it’s cost effective.”
Evaporative cooling is gaining popularity as environmentally conscious South Africans increasingly look for ways to keep cool without resorting to air conditioning. In the driest parts of the country, the systems are actually more common than refrigeration air conditioning in residential installments. “I don’t think there’s a household in Upington that doesn’t have evap cooling in it,” says Philip Coreejes, owner of Hi Power Electric.
Using only water and air, evaporative cooling is the greener alternative both for indoor air quality and for the atmosphere. Unlike air conditioning, which works best when recirculating stale air in a well-sealed building, evaporative coolers ensure a constant flow of outside air. They use no refrigerants that damage the ozone layer. And by using a fraction of the electricity consumed by air conditioner compressors, they avoid warming the globe while cooling your home. John Bass, owner of Fresh Air Environment and Temperature Control in George says, “when people ask me about air conditioning, I ways tell them, ‘if you can possibly use evaporative cooling, go that way.’”
Most evaporative coolers work by trickling water over a porous filter made of treated paper and blowing air through it. As the air picks up moisture, it gives up its heat and the air temperature falls by a few degrees. The more expensive two-stage coolers first use evaporation to cool the water before it comes in contact with the air. This allows greater cooling with lower humidity.
In South Africa, some of the most common brands of single-stage coolers are Cool Breeze and Breezair, both made in Australia. A well established South African manufacturer of two-stage coolers is Protek.
Corporations have been leading the advance of evaporative cooling in South Africa. From office buildings for Cell C and Altech Autopage in Gauteng to factories for Bokomo in the Western Cape, companies are taking advantage of the electricity savings. “It’s taking off like a rocket with power restrictions now,” says Neels Claassen, co-founder of Protek.
Outside of the Kalahari, however, few homeowners are aware of the option. Humidity levels are too high along the Indian Ocean Coast of KwaZulu-Natal, but in much of the Highveld and Cape, evaporative cooling is vastly underutilized. Bransgrove, the owner of Thermodynamics in Cape Town, says that he was skeptical that the Mother City was suited to evaporative cooling until a friend visited Australia to research their home-cooling market. “Every house in Perth has evaporative cooling, and they have the same climate,” he says. People in the industry disagree as to whether evaporative cooling is suited to Cape Town’s most humid suburbs, such as Newlands. But there is no doubt that it functions well from the northern suburbs and beyond.
Evaporative cooling can save money upfront as well. Compared to just buying a couple of window-unit air conditioners, an evaporative system will always cost more, because it requires ducting air from one central unit into each room. But as an alternative to cooling all of a large house with air conditioners, evaporative cooling may come with a lower installation price. For a commercial building, evaporative cooling can cost half as much as air conditioning.
More dramatic savings come when the device is operating. Evaporative coolers generally use one-half to one-six of the power of equivalent air conditioners. Bransgrove says that a central air conditioner for his home might have used 14 kilowatts, whereas his Breezair unit has a maximum power of less than 1 kilowatt. He frequently runs the unit on a low setting that draws little more than 100 watts.
That is a fact that Eskom should appreciate after last summer’s power shortages. Fred Rodo, who has researched the South African refrigeration air conditioning market, says that sales grew 600 percent over the last 10 years. He draws a direct connection between the resulting electricity consumption and the load-shedding debacle.
Beyond the stress on the electricity infrastructure and the accompanying greenhouse gas emissions, air conditioning still poses a threat to the ozone layer. Though CFCs have been banned in South Africa, their most common replacement, an HCFC known as R-22, also depletes ozone, though to a lesser degree. Its weaker chemical impact on ozone is offset by the huge increase in air conditioner sales.
Of course there are ways to keep cool that use even less electricity than an evaporative cooler—or none at all. Ceiling fans typically use well under 100 watts. A couple of R1500 turbine ventilators such as the Whirlybird use no power and can release trapped heat from the roof space. Ceiling insulation can cool a home considerably in summer. Cellulose insulation has the added benefit that it is made from recycled newspaper. Finally, if you take a cool bath and then stand in front of an open window, wet and naked, you become a human evaporative cooler yourself.