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Comment by bserge | Hacker News Reader

It won't eliminate A/Cs. People could use white or silver paint right now. They don't. It "looks bad".

Not to mention that it won't do anything about humidity. Even when it's not that hot, high humidity feels awful. Also not good for the house and the items inside.

Yeah, reflective paint isn't obstacle to be overcome here, it's the almighty HOA.

This is a place where the coercive hand of the state might be helpful, if white paint is really so good that it's going to eliminate what is a major contributor to global warming.

It doesn't only look bad, it reflects the sun and probably into your neighbours/road etc at different times of the day. Silver roofs are banned here for that reason.

I assumed anyone sane would use flat/matte.

It was corrugated iron, and was very common, it's not polished and looks matte, but still when the sun hits at the right angle it reflects. It has to be painted now.

https://en.wikipedia.org/wiki/Corrugated_galvanised_iron

Could still be a big deal in South America, Africa, and Asia. They have fewer issues with buildings that look bad, but are also less able to afford A/C. Those people are also going to be most affected by climate change, and would want cheap ways to reduce the impact of intense heat waves.

It does seem a little grotesque if we're going to stick them with the problem and not even be willing to make aesthetic changes. Particularly when we're disproportionately responsible for the problem in the first place.

Stick them with the problem? I'm not sure what you mean.

And whether we're willing or not to make aesthetic roof changes has little impact on the climate.

Saying "hey guys, tough luck, you're on your own, we refuse to change anything to reduce our wildly high per capita emissions" is sticking them with the problem. The claim of this article is that this white paint can reduce roof temperatures by 4.5 degrees centigrade, which is plausibly enough to substantially reduce demand for air conditioning, which is a major contributor to global warming. If the _only_ problem with this plan is that some people don't like the aesthetics -- I'm not saying that is the case, but granting it in this discussion -- it sounds like a frivolous objection.

Painted my workshop roof white, temperature drop was noticeable.

Needs a repaint though, after 6 years it's washed off. Then again I used the cheapest paint I could find, just to test it.

Air conditioning uses a bit more power than I thought, but it's still not that much.

Installing a couple solar panels would probably be much more effective.

I don't think they're exclusive strategies, and paint has some other things to recommend it like much simpler, lower-cost installation.

They don't have to be exclusive but you'd obviously want to do the more cost-effective one first.

> paint has some other things to recommend it like much simpler, lower-cost installation.

I wouldn't say painting a roof is simpler than mounting 4-6 solar panels. Are you sure it's cheaper?

Just taking the first Google results at their word, a roof painting is around $3000 and a solar panel installation around $15,000. Of course there are many variables to consider but I think it is likely to hold true in most cases.

That's for bigger solar installations. A 2kW system would cost about $4k after tax credit and it would probably save you a lot more energy.

And how many years will the paint last?

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