White is the new green

Winter’s over and, in this case, that’s one big relief. 2024 was the wettest winter in the Western Cape since we started recording rainfall, and it was close to record-breaking cold over much of the rest of the country, too.

It was cold and miserable and bleak, and we all can’t wait for summer.

Rain, rain

Okay, lots of rain is good for the dams, which are full, but it was not great for the people whose roofs blew off in storms, or whose houses were washed away in floods as farm dams burst. South Africa’s oldest weather station, Observatory, recorded the wettest July since 1850, when it started recording, and the single wettest month in more than a century. So, yeah, you’re probably really looking forward to summer. But what’s the bet we’re gonna have a record summer, too? It’s pretty likely considering what the northern hemisphere was like while we were freezing our butts off.

Record highs all over the world

The European Union’s Copernicus Climate Change Service (C3S) declared the northern summer of 2024 the hottest on record, with wildfires in Greece, France, and the USA, airports being closed in the UK because runways buckled and started melting, and people – literally – dying of heat-related issues all over Europe. And guess what: 2023 was also the hottest summer on record. Are we seeing a pattern here?

Something’s gotta be done

Our first instinct is to turn up the air-con and, sure, that helps in the short term. But that is definitely only a short-term solution that – as Mark Radka, Chief of the Energy and Climate Branch of the United Nations Environment Program (UNEP), says – leads to more longer-term problems. ‘Cooling is a big contributor to global warming,’ he says. ‘Much of the existing cooling equipment uses hydrofluorocarbon refrigerants, which are potent greenhouse gases, and they use a lot of energy, making them a double burden for climate change. Even with the phasedown of hydrofluorocarbons required by the Kigali Amendment to the Montreal Protocol, business as usual means emissions from refrigeration and air conditioning are expected to double by 2030 and triple by 2050, rising from 7% of global GHG emissions today. Right now, the more we cool, the more we heat the planet. If we are serious about reversing current trends, we cannot go about cooling our planet with a business-as-usual approach.

So, what do we do?

We need to think creatively, but that does not necessarily mean we have to come up with bold new unicorn ideas. Sometimes the answer has been there all along. Take, for instance, the culture of building with thick walls in hot climates, and painting houses (and even flat roofs) white. It worked for our ancestors and it still works, but – with modern technology, and a bit of out-of-the-box thinking – we can improve on it.

That’s cool, but this is even cooler

Even the simple limewash that traditional communities used to paint their houses reflects the sun’s energy, but only between 80% and 90% of it. So researchers, engineers, and paint manufacturers have been constantly seeking to make the ‘whitest’ and most reflective of white paints. In 2023, Purdue University researchers won the Innovation Award in the sustainability category of South by Southwest Conference & Festivals (SXSW) and the Gizmodo Science Fair for their innovative paint that has been recognised by the Guinness Book of Records as the world’s whitest paint.

The novel paint reflects 98.1% of the solar heat away from its surface, which means that it absorbs less heat from the sun than it emits, so surfaces painted with it are passively cooled to below the surrounding temperature without consuming any power at all. It really is a game changer. Tests showed that a building that was painted with the new paint was 4.4ºC cooler than its surroundings in the middle of a sunny day, and 10.5ºC cooler at night. Purdue professor of mechanical engineering, Xiulin Ruan, said that painting a roof of 93 square metres would give a cooling power of 10 kilowatts. ‘That’s more powerful than the central air conditioners used by most houses,’ he adds.

And it’s not just houses

In 2019, Los Angeles experienced its hottest ever summer (did I mention that a pattern was emerging?). So they came up with an innovative idea that can easily be replicated in estates. They painted all the streets in a small part of the San Fernando Valley with reflective white paint, and found that the surface temperature of the roads were between 5.5ºC and 8.5ºC cooler. Even more importantly, though, says Greg Spotts, Chief Sustainability Officer of LA’s Bureau of Street Services (Streets LA), ‘locations near the cool pavement were, on average, 1.1ºC cooler than the surrounding areas.’ He proudly states that the effects can be seen from space as these cooler neighbourhoods show clearly on thermal images from the International Space Station. And that was using an older generation of heat-reflecting paint.

So, c’mon, paint the town estate red white/green

It almost doesn’t matter where you start. Roads are easy, but you can also paint houses and even roofs with white reflecting paint. While Purdue’s paint is not yet commercially available, there are many reflective paints on the market that fit somewhere between traditional limewash or not-so-traditional titanium dioxide paint and Purdue’s super-white paint. So, what are you waiting for? Let’s paint the roofs and roads white because white is the new green.