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Comment by vanderZwan | Hacker News Reader

I have one "problem" with airconditioning: it's a "cure" for cooling down a building after it heats up too much, but the more cost-effective, sustainable solution is prevention.

If we prioritize battling the urban heat island effect first, the remaining temperature problems can be tackled at a much lower energy cost with with airco.

[0] https://en.wikipedia.org/wiki/Urban_heat_island

[1] http://www.lowtechmagazine.com/2012/03/solar-oriented-cities...

[2] http://www.lowtechmagazine.com/2012/03/solar-oriented-cities...

[3] http://www.lowtechmagazine.com/2012/03/solar-oriented-cities...

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Isn't the "urban heat island" effect a fundamental property of the way we've designed and built our cities?

To fix it, wouldn't we need to redesign buildings to have things like green roofs and use construction materials that reflect heat. And we'd have to tear up much of our paving and roads and replace them with trees, water, and green space. That all sounds nice, and it's a good principle to consider when designing new urban areas.

But it's extremely expensive and disruptive to go rebuilding existing cities, and all the construction itself would have an environmental cost. Surely air conditioning is cheaper?

First thing to do is stop making the problem worse.

Last I checked we are still building our cities. Mine is in the process of knocking down all the one story commercial space and replacing it with six story mixed use buildings.

Increasing density in urban areas by building up is the right thing to do, compared to expanding urban areas which would require more paving, more roads, and more inefficient use of land.

It's the way we design those new buildings that's important.

Why is that bad? people complain about the enormous costs of accommodation, to which the main solution is simply to build more.

You're just trading off energy spent cooling denser cities vs. increased transportation in less dense cities.

Increased density means fewer low density buildings and paved surfaces elsewhere. Urbanization is a massive net positive for the environment.

It's a lot easier to insulate multi story buildings. Volume grows faster than surface area.

Your proposed alternative is to increase urban sprawl?

What? No. My point is that each new building is a chance to do better. Claiming it’s too late because we have built up areas is helplessness.

If you double the size of a town and build the new half well you solve more than half of the problem.

I like the idea of moving towards Caves of Steel, but with parks on top and atrium areas where streets currently are.

It might also be possible to use a heat-stack effect to draw the air out of the city as a whole.

If we could adopt a combination of subways, dreaded e-scooters, bikes and golf cards for elderly and people with disabilities we could make this happen. Some European cities have huge pedestrian zones and it works.

> But it's extremely expensive and disruptive to go rebuilding existing cities, and all the construction itself would have an environmental cost. Surely air conditioning is cheaper?

It's at best a cheaper up-front investment. And while it is one thing to think about the limits of retrofitting old buildings, that is no excuse to not do better with newly constructed ones.

You're right!

With that said, it might be worth considering that it will often be easier to pitch "add air conditioning" to people than "tear down, reorganize, and rebuild the whole metroplex at once". Greatly disrupting the lives of millions of people at once is not something to be taken on lightly, easily, or quickly.

The dream is amazing, beautiful, and without question what's best for the planet and for us. There might be something to be learned from nuance in terms of how to get there is all.

I completely agree with you on this, but changing entire megapolis's is not going to be an easy task. Here in Southern California we have a huge heat island effect, due to the non stop city going from South Orange County to Ventura county (close to 100 miles) and from the ocean to at least 50 miles inland. I've read it can cause rain storms to completely bypass this area.

Wow, there's some fantastic mapping of this effect from a few years ago: https://calepa.ca.gov/2015/09/16/urbanheat/. Links to a study and lots of data produced from it.

Southern California: "urban heat archipelago".

From the linked page:

"largest effect is in southern California, where the urban heat islands blur together to form an “urban heat archipelago” with average temperatures up to 19° F higher in the Riverside-San Bernardino region at the eastern end of the basin."

If it is really 19° F higher in Riverside due to urbanization(hard to believe that really), I can see why correcting historical temps for urban heat island effects is so necessary. How to do that accurately must be fiendishly difficult.

Houston would still be unbearable even without urban heat island effect. But yes, it would be slightly cheaper. But the cost to reengineer the entire city would far outweigh the marginal increase in energy costs to cool certain areas of buildings.

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