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Comment by epolanski | Hacker News Reader

To me it's crazy people run so much AC at home.

It's like making global warming a worse problem with AC, so it gets hotter and we use more AC.

I live in Rome, Italy, we had 40C (104F) degree max temperatures during day, and even at night it doesn't fall below 29C (84) and we survive without AC just fine, not just me but the rest of my family in their houses too, of course it is sometimes uncomfortable, but that's summer.

The worst offenders though are the many shops that blast AC 24/7 and have their doors open! Put some goddamn sensors and sliding doors!?

I just can't look at it. Even worse, electricity comes and goes all time during summer and it's hard to work at times (I'm full remote).

I'm fully convinced nobody gives two damns about global warming and our own impact. It's better to just ignore our actions and focus on evil corporations so we keep avoiding doing anything, maybe buy and change our EVs every 3/4 years as it didn't make it worse.

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In places like Houston, which is effectively built on reclaimed swamplands, it's not the just the temperature, the humidity plays a huge part too. When it's 40C and humidity is at 100% and wet bulb temperatures are approaching 30+C, lack of AC becomes a life threatening problem. It becomes practically impossible to cool off and maintain a safe body temperature, especially for the very young, chronically ill, or elderly people.

> we survive without AC just fine

There were 5,600 deaths across Spain, Italy, and Germany in the 2023 heatwave that could be attributed to a lack of AC [0][1]

Just because you and your family have been fine doesn't mean others can.

AC is a critical need in increasingly hot environments.

[0] - https://www.wsj.com/world/europe/hotter-summers-kill-thousan...

[1] - https://iris.who.int/bitstream/handle/10665/339462/978928905...

Here's a comparison of Houston and Rome climates: https://weatherspark.com/compare/y/9247~71779/Comparison-of-...

Note the temperature and especially the humidity sections.

I'm commenting on Rome though, my city. Not Houston.

The point is that Houston is both hotter and more humid. People have already died due to heat because of this loss of power. The AC is not a luxury but a necessity.

I'm not commenting on the usage of ac in Houston (albeit it's nonsense to raise a city in such a place) but in Rome.

Perhaps your original comment made it to the wrong post? This article was about the problems Houston is having from power and AC being out for days so people are naturally expecting comments and their ensuing discussion to also relate to this.

Homes/buildings in your area are built with not having AC in mind - window locations, shade, insulation, etc is all purpose driven. Homes in Texas and generally the US are built with AC in mind, so we can’t not use it - it would get 104 inside.

I've also noticed that newer homes tend to have this problem more than older ones. They're better sealed thermally, so while they're more efficient to keep cool, when they get hot they stay hot for a lot longer. Great for winter, not so much for summer heatwaves.

I used to live in an apartment built in the 70s which was a pain to cool or heat because it was so badly sealed. But the one benefit it did have is that on hot days with cool nights it'd very quickly cool off, without needing AC. My current place requires AC unless I mind waiting until 4am for it to cool off.

It's pretty easy to temporarily "unseal" a house though - open doors/windows.

A well sealed and insulated house takes less to cool too, though. It doesn't just help in winter.

Sadly, in central Kansas where I live, it regularly forgets to get cool at night. Last summer we did our corn silage chopping at night and slept in the day, as we were getting burned trying to operate equipment. At night it was still very hot and muggy. IIRC the dewpoint was in the mid-to-upper 80s F.

AC isn't a problem if the energy feeding it is carbon neutral. With a strong mix of renewables and nuclear this is achievable, but instead we continue to burn coal and natural gas to provide base load.

Visited NYC several times. Metro was unbearable in summer because trains heated up outside and blasted the warm air into tunnels and stations through AC.

AC doesn't really create heat though, aside from minor amounts from the compressor/fan motors, it merely moves it from inside to outside, or into the metro stations as you mention.

Yes, AC moves heat from inside homes outside into the city.

My point is that it doesn't create heat, thus does not contribute to climate change on its own. Only the energy source that powers it potentially does.

Since ACs are pretty far from 100% efficient, they turn electricity into heat. There's also heat generated along with the electricity because generation isn't perfect either.

The HVAC fan alone in a surban house can draw 1KW. That’s pretty much all heat.

The AC cools the house at the cost of many more KW.

The house gets cooler but this is all heat from the electrical usage.

To put that into perspective:

The AC cools the house using about 3-4kW, total.

The roof on the house (assuming 29N because the article is about Houston, so between 10AM and 2PM, that's a Solar irradiance of 1kW/m^2) is receiving 157.9kW of sunlight, and then absorbing about 85% of that.

Lowering energy usage doesn't solve the climate problem it just slows the devastation. We need to use clean energy regardless if it's for AC or for work to have a worthwhile impact on that half of things. From another view: it's better to live well sustainably than be proud of unsustainably living miserably. To do that we need to convince people to pay more for electricity generation instead of pointing out they likely wouldn't die if they used less dirty energy.

Whenever I visit Italy in the summer I check to make sure the hotel I’ve booked has AC. I got burned by that one hot summer in Milan.

Heh, just got burned by this in the Czech Republic. Far on the east side, hotel advertising A/C but it’s only in a common area - not in the room itself.

Just about drove me insane.

Many homes in the US are not build with stone but thin wood. Houses in Europe with stone take some time to heat up. We lived in a 100 year old house in Berlin and it took 2 months until the walls were warm. Also took some months in winter until walls are cold again.

[Edit] This is not about insulation but heat capacity.

such houses are great in mild climates, but the us is generally not mild.

thin wood as an engineer has many advantages over stone. Stone seens stronger but often it isn't where strength matters while being stronger where it doesn't-

Modern "stick built" homes in the US are well insulated and actually quite efficient. Stone walls would be a poor choice in most areas in the US due to extreme conditions.

As you mention, once a stone house heats up in the summer, that is an incredible amount of thermal mass to cool. Your AC would run non-stop. Similar issue in the winter, super high heating costs in cold regions.

This is not about insulation but heat capacity.

Heat capacity doesn't mean much unless the walls are several feet thick.

The frost line where I live is around 5 feet deep into the ground- meaning that footings for any building have to be that deep to avoid shifting as the ground freezes and thaws.

Summer months thick stone walls can be nice if you are able to keep humidity out, but if you don't and your walls actually stay cool you're dealing with a lot of mold and mildew since water will be condensating 24/7.

"several feet thick."

I don't know how thick a feet is, where we live we don't measure distances by the length of the feet of the king.

But I have lived for 10 years in a house with 30 cm thick walls and it has a tremendously positive effect, when outsite it is 30C and inside the walls are still 20C into July.

"mold and mildew"

Didn't have that problem in 10 years. This more happens with modern insulation than thick stone walls from my experience YMMV.

There's a fantastic service called the internet, which helps with things you don't know about. According to Google, 5 feet is roughly 1.5 meters. That means that the ground is frozen solid on average 1.5 meters below surface level in winter. However much thermal capacity your walls have, it won't be long before your attempt at heating or cooling your living space is competing directly with the outside environment. It is less of a concern in summer, since the difference between inside and outside is much smaller, but critical for energy usage in winter.

As for mold and mildew, you only get that with modern insulation if you have a poor envelope- i.e. drafts in the walls due to improper sealing. It's not the sort of thing drier climates have to worry about at all, but in very humid environments such as where I live, preventing condensation inside is important. That means not having walls that are cooler than the dew point of the air getting inside.

Basements here are very prone to getting mold or mildew, because (a) they have solid walls, (b) are kept cool via the earth acting as a heat bank, and (c) will readily absorb moisture through the stone or cement.

Most around here have some sort of sealant paint or active dehumidification running in summer to avoid mildew. If the basement walls didn't have to be load bearing, solid wall construction would absolutely be the last choice for basements because they're definitely the worst for thermal and moisture resistance properties.

Those walls would be nearly 30C in the inside already, if my house was built with them. The average temps for the past few weeks (low + high / 2) have been 30-32C. Its still somewhat early in the hot season here, so that will still go up.

There are months of the year where it doesn't get less than like 32C. save for rare cold snaps were it'll dip down to 26C or so for an evening or two.

My pool, which also has some decent thermal inertia, is already at 30C. The average temperature is still going up outside.

All of Europe is further north than most of the US. This does some big things for the climate.

Yeah, and heat capacity is the last thing you want for an object in a hot environment where the sun shines on it.

I've seen shaded portions of my concrete slab at 36C at 1AM

Heat capacity just means the AC is removing the heat coming from the stone walls, as opposed to the heat from the sun shining on it.

The world uses vastly more energy for heating homes than cooling them. It would be more energy efficient to live in the desert using AC than burning natural gas for heat in northern countries.

>To me it's crazy people run so much AC at home.

Tell me you've never been to Texas in July without telling me.

How humid is it in Rome during the summer compared to Houston?

No even in the same ballpark. Houston is literally built on top of a swamp. The humidity is oppressive.

Average dew point July

62F Rome 74F Houston

https://www.timeanddate.com/weather/italy/rome/climate

https://www.timeanddate.com/weather/usa/houston/climate

Noticable vs humid and uncomfortable bordering on oppressive

https://www.weather.gov/images/tbw/dewpoint/DewPointScale.pn...

*edit to fix Houston dew point

Imagine priding yourself on the amount of discomfort you can endure

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