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Comment by sammalloy | Hacker News Reader

The easiest first step is to start installing white roofs in urban areas. This should be national policy by now. It’s been four years since this policy was recommended and nothing has been done.

https://e360.yale.edu/features/urban-heat-can-white-roofs-he...

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One state in Australia has banned black roofs. I’d think the others will follow along. But in the mean time developers are pumping out as many new black roof urban sprawl developments as they can.

If you mean NSW, the new planning minister has recently caved in to developers and decided to keep killing the environment: https://www.smh.com.au/national/nsw/minister-bows-to-develop...

Why are white roofs hard? It's just paint. You could spray it on with a hose.

Oh but you could save money by not spraying roofs…

It's probably not gaining much traction because it interferes with aesthetics. Architects would need to embrace it.

I'm not sure how much architects can do. White gets dirty quite easily and is prone to yellowing from UV light.

White is not by nature prone to yellowing. Some paint are (the organic component of the paint), but if you are using a lime wash it will never turn yellow and TiO2 as a pigment is very stable.

What gets it dirty on the roof? You also generally can't see the roof except looking down from taller buildings?

Houses aren't cube shaped, generally. The roofs are sloped and the front side can easily be seen from ground level.

In some places, yeah. In my experience buildings higher than about 5 stories do have flat roofs ("cube shaped"). Almost all housing in my hometown don't have sloped roofs because it's mostly apartment buildings rather than detached homes.

Barium sulfate specifically.

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