There was a good study on this a few years ago that ran the numbers on this and landed on white paint for residential homes as the best option, for a few reasons, if I remember correctly:

- Installation, maintenance and transmission costs are lower when solar is aggregated on farms - Solar offsets air conditioning, but that moves the heat outside. White roofs reduce the need for AC, which helps significantly with urban heat scenarios

A quick search yields a UCL study, which supports the lower claim: https://phys.org/news/2024-07-roofs-white-city.html

A good percentage of Pakistan did this recently and removed 35% of demand off of their grid https://www.ted.com/talks/jenny_chase_solar_energy_is_even_c...

I'm now wondering if painting a roof white is better than covering the same roof with solar panels and using that to drive air conditioning (in the house). My intuition is that painting it white must be vastly more environmentally friendly, although it probably doesn't reduce the temperature very much compared to aircon.

Back-of-the-envelope - Road area. World road length ≈ 60–70 million km. Using an average paved width of ~8–10 m ⇒ area ≈ (0.9–1.3)×10¹² m². Earth’s surface is 5.1×10¹⁴ m², so roads cover ~0.09–0.13% of the planet.

- Albedo change. Dark asphalt is ~0.05–0.10. “White” coatings can push toward ~0.4–0.6 (fresh), but weathering quickly dulls them. So a plausible Δalbedo for roads is +0.2 to +0.5.

- Global albedo change. Δα_global ≈ (road fraction) × (Δalbedo_road) ≈ (0.001)×(0.2–0.5) ≈ +0.0002 to +0.0005.

- Radiative forcing. Globally averaged incoming sunlight ≈ S₀/4 ≈ 340 W m⁻². Forcing from an albedo change is ΔF ≈ −Δα_global × 340 ≈ −0.07 to −0.17 W m⁻².

- Temperature response. Using a standard sensitivity ~0.8 °C per W m⁻² (≈3 °C per CO₂ doubling): ΔT ≈ −0.05 to −0.14 °C at equilibrium.

White roads could potentially be blinding, but yeah something lighter than what we do currently could be very worthwhile. It'd have much higher nighttime visibility too.

Teslas will start crashing like there’s no tomorrow.

Paris and other climate accords have much ado about fractions of a degree, leading me to believe that that's highly consequential.

Fascinating. So no such satellite data exists. Thanks for the insight, makes the linked write up much more satisfying.

Thanks for the video!

Yes, from chatgpt:

These are so-called “radiative cooling paints.”

Here’s how they work:

They reflect almost all sunlight, so the surface doesn’t heat up.

At the same time, they emit thermal radiation in a specific infrared range (around 8–13 micrometers) that can pass through the Earth’s atmosphere and escape into space.

Such paint can make surfaces cooler than the surrounding air, even in sunlight.

So it doesn’t convert solar energy into another form — it selectively reflects and emits infrared radiation that sends heat directly into space.

Same. Part of the background info on this is PSUs are usually most efficient at (or just under) 50% load. They are also more efficient at 240 V than 120 V, if you have the circuit. So the real efficiency can end up varying significantly, depending how you use it. The efficiency is not usually much to write home about in terms of your electric bill, but it does help drive the ability for the PSU to cool itself passively.

These type of calculations don't really work for things like skyscrapers, high-rise apartment complexes, or the slum-towns of Asia and South America, and conversely for very sparsely populated regions like the fringes of the Sahara. Antarctica has people too but it doesn't make any sense to count it as "populated".

I think we can just draw an outline around cities, towns, and villages and count that area as populated, no matter how many people are actually in there.

For long stretches of land where there's just a single highway going through and a few gas stations, motels and shacks, totaling maybe <100 people for many miles around, we can count that land as unpopulated.

Isolated islands with indigenous/uncontacted tribes, not sure.. We may have to consider their population growth and see if they're in "equilibrium" with "nature" and so on.

A simple glance at Google Earth shows large parts of Russia as clearly unpopulated/undelevoped, then there's the deserts of China and Africa, and some natural land in the Americas, and finally of course there's Antarctica, until the Elder Things awaken.

> There is plenty of land for everyone, especially if we start to construct efficiently.

I was afraid someone will get it the wrong way: I hope it STAYS that way; that the majority of the planet remains unpopulated, but humans learn to make better use of the space we're already occupying.

In my country (Australia), the cheapest I can get is like $250k USD equivalent... But that's a shack in the middle of the desert in some tiny ghost town. Even in a normal small town, houses are like $350k USD minimum. In capital cities, it's like $500k USD minimum for a tiny apartment... Top salaries for top senior software devs are like $130k USD before tax, taxed at about 40%... So take home pay is like $78k USD net income. Rent is like $22k per year minimum. Impossible to get fixed-rate mortgages; banks only only do variable rate... 20% minimum deposit. This is in a country with a LOT of spare land which is scarcely populated.

Rural Russia as well. But you will probably have to get your water from a well and poop into a latrine.

IMO the real problem is that the monetary system creates asymmetries which create monopolies, which force everyone to participate in 'the economy' through rigid, inefficient, bureaucratic structures. People are literally not allowed to service each other, even through they have the time and capacity to so; simply because they do not have access to a specific currency which they are forced to use... That same currency is not universally scarce though; it's basically handed out to their biggest corporate competitors in large quantities via government contracts and from banks in the form of low interest loans. It creates a kind of fictitious planned economy which becomes increasingly inefficient and bureaucratic by the day; the money is the only quantity which is increasing (and only for some people), almost every other economic metric is decreasing. The real economy is hollowing out.