Words: Sean Woods. Article from the Popular Mechanics July 2015 issue.
One man’s collaboration with UCT aims to improve the lot of shack dwellers.
Next time you bitch about oppressive summer temperatures while scuttling between your climate-controlled vehicle, office and home, spare a thought for those living in tin shacks. To say the occupants swelter is an understatement. In fact, tests have shown that when ambient temperatures reach 36 degrees, temperatures inside, conventional shacks soar to a staggering 47 degrees plus – making life pretty much untenable. Happily, a collaboration between electronic security expert Mark Algra and Dr Kevin Winter from the University of Cape Town’s Environmental and Geographical Science Department aims to change all that.
The project – part of Cape Town’s World Capital Design initiative – kicked off in November 2014 when Algra and Winter constructed two typical 2 x 2,5 metre shacks on UCT’s grounds. One was left stock-standard as a control, while the other was clad with experimental materials and incorporated various adaptations to help bring internal temperatures and humidity levels down. Both were rigged with high-resolution monitoring sensors to capture temperature and humidity data every three minutes, allowing Winter’s department to determine exactly how the materials and designs performed in real time.
Says Winter: “Our aim was to find simple ways of reducing the temperature in the experimental shack by 10 degrees compared with the conventional shack, and at least 2 degrees below ambient temperatures using low-cost materials that were readily accessible.”
Simply glueing fabric derived from recycled PET bottles to the outside and painting it with white PVA helped lower temperatures by 3 degrees. Adding a pitched roof brought another 3 degree reduction. They then cut two small holes at the base of one wall and placed two small containers with wet charcoal near them to suck cooler air into the shack. On the opposite side they cut a few holes in the ceiling and placed an inverted plastic basin fitted with a curved plate on top to create a venturi effect and suck hot air out. Says Algra: “Once we incorporated this cross-flow adaptation we immediately began achieving our desired temperatures – that’s when we realised we were on the right track.”
Other adaptations included smearing a paper cement mix on the inside walls to provide insulation in winter and remove the typical unhygienic cardboard cladding. Giving the pitched roof wide enough eaves to channel water away from the walls and on to a micro garden. Plumbing in a basin, allowing occupants to dispose of grey water into an aerobic soakaway at night. And fitting a “litres of light” bottle (that is, a 2-litre cooldrink bottle filled with water) to distribute light during the day.
Currently, Algra and Winter are busy experimenting with fire-retardant materials. They are also planning to retrofit 10 shacks to see how their improvements perform for families in the real world. Says Algra: “Ideally we would like to turn this initiative into jobs. If people want to climb in and develop what we’ve achieved further it would be great.”
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