Check out the inverter type ones such as this one [1] It isn't light but it is quiet and adjusts the amount of power it uses depending on cooling needs much better than a typical window unit making it more efficient.

[1] https://www.midea.com/us/air-conditioners/window-air-conditi...

The Midea U window AC units are a really good product. I am easily cooling a roughy 1,200 square feet space with only one of the 12k BTU units and a few ceiling fans, and it typically gets into the 90’s F here in the summer with significant humidity.

No affiliation to Midea just a satisfied customer.

I agree. The U shape is a gimmick, but a good one. It helps it be quieter inside, but even outside they are quite quiet. I have whole house AC, but I like the windows open, I like being hot. Just not when I’m sleeping. Basically only downside is a truly terrible app that is the only way to access just a few features.

Terrible doesn't begin to describe that app. Honestly what does the turbo button in the app even do?

I have one in a room on the far end of the house that the main AC can't reach, it helps reduce power usage since I can keep the rest of the house warmer.

Window units really only exist at all because of buildings that can't accommodate better designs for either practical or legal reasons. There's just no amount of innovation that can make it so that having the intake and the outtake right next to each other without a nearly perfectly sealed box on one side (ie. a fridge or a freezer) is gonna be anything but a big ugly noisy energy gobbler.

If you can't have central, you should have mini-split, and that's where all your problems get solved. If you can't get mini-split because your landlord won't let you drill conduit to outside then you're just kinda stuck and the laws of thermodynamics are your enemy, not a lack of innovation.

Idk this "toshiba" AC has a built in heat pump and operates at super quiet levels. Would I call it a "breakthrough", likely not. But it is a meaningful improvement over an AC released decades ago.

https://www.homedepot.com/p/Toshiba-14-000-BTU-12-000-BTU-DO...

Mini splits are widely used and have become dramatically more economical and popular over the last decade or so. They are much quieter and more efficient than window units.

Some areas (cough nyc cough) may need some regulatory breakthroughs but the technology is there.

Can you expand on the regulatory issues or provide a pointer?

"Lisa, in this house we obey the laws of thermodynamics!"

It's physics and thermodynamics. It's basically the same as with any heat engine, internal combustion engines included.

There is a certain maximum theoretical efficiency that is not 100%. When we build real machines (not theoretical ones) there are real world losses like heat loss, fluid flow friction, moving part friction, electrical inefficiencies, etc. Those real world losses van be gradually worked on over time, improved incrementally to yield small gains in efficiency. But never large ones, and never more than the theoretical max efficiency, which is not 100%.

It's like hybrid cars (not plug in hybrids, but just gas powered hybrids), they've doubled or trippled the mileage compared to a comparable regular car, but they will always need gas, they will never be 100% efficient.

Same with this. There will always be some fundamental electrical losses in the copper in the motor, air gap losses in the motor, friction in the bearings and fluid, heat losses to the environment, etc. It's the cost of doing the work. There is no free lunch, so we can only incrementally improve the little losses over time.

My understanding is that heat pumps can be over 100% efficient because they're actually moving heat from A to B where one side is the outside environment. It doesn't violate thermodynamics if you view the Earth as a closed system. The heat pump itself is not a closed system.

Thanks for highlighting this because it's a common misconception.

"The coefficient of performance or COP (sometimes CP or CoP) of a heat pump, refrigerator or air conditioning system is a ratio of useful heating or cooling provided to work (energy) required.[1][2] Higher COPs equate to higher efficiency, lower energy (power) consumption and thus lower operating costs. The COP usually exceeds 1, especially in heat pumps, because, instead of just converting work to heat (which, if 100% efficient, would be a COP of 1), it pumps additional heat from a heat source to where the heat is required. Most air conditioners have a COP of 2.3 to 3.5. Less work is required to move heat than for conversion into heat, and because of this, heat pumps, air conditioners and refrigeration systems can have a coefficient of performance greater than one. However, this does not mean that they are more than 100% efficient, in other words, no heat engine can have a thermal efficiency of 100% or greater. For complete systems, COP calculations should include energy consumption of all power consuming auxiliaries. The COP is highly dependent on operating conditions, especially absolute temperature and relative temperature between sink and system, and is often graphed or averaged against expected conditions."

https://en.m.wikipedia.org/wiki/Coefficient_of_performance#:....

More detail here:

https://physics.stackexchange.com/questions/489467/can-a-hea...

In short, a heat pump is more efficient when compared to using the energy to directly generate heat because it's more efficient to move heat than generate it.

That means you need somewhere to move the heat to, and the thermoynamics of heat capacity are not forgiving if you are trying to make something lightweight. You need atoms and lots of entropic states to store heat :)

They're not talking about that 100.

Thermodynamics are harsh mistress... Add that to limitations on what can be used as refrigerants. The reality that these systems need to operate with rather long duty cycles for decade+ at minimum. And the reality is that there isn't much magic in how they operate. Compression and expansion of gas.

Computers are actually a very special case. They don't really do any physical work in sense other stuff does, thus miniaturization gives lot of gains there. I have long said that small drones are answer to flying cars. We have them and they are small, but lifting people is hard work.

AFAIK the physics of heat pumps is considered to have been fully figured out for ages and all that's left is the engineering. Maybe it wasn't considered a "sexy" enough topic to nerd out over and hyper-optimize?

Edit: it might also be an issue of diminishing returns of better efficiency compared to how difficult it is to produce and maintain a better unit. Thermodynamics can be a pain like that.

Patents, intellectual property, etc. It's why every appliance is trash nowadays. Big corps are IP holders, and there's only so many ways to engineer certain actions. Regardless even if you try to startup a company you'll be pushed out by the control big corps have over manufacturing.

We need to start nullifying IP if we ever hope to see innovation.

Probably not this, most IP can be worked around, and especially in the area of AC operations and thermodynamics, that hasn’t changed in almost a century.

We got a U-shaped one for a big open attic space and I'm a fan of it. It cost more and was a little bit more drama to install (came with a big support bracket thing), but it's very effective and quiet. We meant it as a stepping stone to eventually putting a mini-split setup on that side of the house, but it might end up just being the long-term solution.

EDIT: Oh lol, the unit we got was actually one of those Midea ones linked in a sibling comment.

I have pondered this as well and studied it a bit. I feel that there is room for new tech that can help with this increasingly dire problem.

Thermoacoustic refrigeration seems to be one of the more promising technologies but I would love to hear about others.

As I mentioned elsewhere: https://news.ycombinator.com/item?id=31791936 there is a company that claims to use thermoacoustics for general heat-pump duty. I believe they are targeting European style hydronic heating. Aiming to be efficient whilst still producing the 80c water that many older hydronic systems here in Europe still require.

Interestingly, they aren't that loud because any sound lost is energy lost, so they try very hard to 'keep it quiet'.

Thermoacoustic... love to hear about others :) yes pun intended.

Talk about moving the goalposts. You asked, people answered. The revolution is that you can now buy an 8000 BTU unit that weighs little, costs almost nothing, and can be installed anywhere in a few minutes.

Most poetically answered by Flanders and Swann:

The First Law of Thermodymamics.

Heat is work and work is heat

The Second Law of Thermodymamics:

Heat cannot of itself pass from one body to a hotter body

Heat won't pass from a cooler to a hotter

You can try it if you like but you far better not-a

'Cos the cold in the cooler will get hotter as a rule-a

'Cos the hotter body's heat will pass to the cooler

Heat is work and work is heat and work is heat and heat is work

Heat will pass by conduction and

Heat will pass by convection and

Heat will pass by radiation

And that's a physical law

> And pretty much everyone in the world (except those with central air) needs a couple of air conditioners now.

Absolutely not. Where I live we had 34°Ctoday but I would still never buy an A/C unit, which will ruin your health (heat/cold shock, bad air moisture levels, ...), waste immense amounts of energy and makes leaving the house a pain as the rest of the world becomes uncomfortable. Most of my friends here earn very well but I can't think of anyone that would see a reason to buy one. Live with the temperature and adjust - like the famous Iberian or Mexican siesta, where you simply accept that midday are low energy hours.

But even beyond this, the reason for A/C use is just bad architecture and city design. More trees in the streets can lower the temperature in the street itself and nearby residences easily by 1-2 degree. Less absorbing surfaces (asphalt, stone sidewalks, ...) make another difference.

And as regards the houses, there are plenty of ways for passive and energy efficient buildings that keep cool. In the middle east they have built self-cooling houses for centuries.

And in all this, even if you are stuck with bad streets and architecture, you can simply adapt, use efficient ways to keep cool (a fan can work wonders) and drink warm rather than iced drinks and your circulatory system will thank you as you don't switch regularly get shocked with 10-15° differences and you will sweat much less.

I also won't buy AC for myself anytime soon, but I'm still young and healthy. Older people have a lot more serious problems with heat waves.

I'd been using a window unit for the bedroom but got sick of taking it in an out and decided to see how long I could manage without it. Now I prefer no air conditioning because of the reasons you state above - it feels much more comfortable being outside on hot days. I keep the windows and doors closed during the heat of the day then open them up when it's cooler outside than it is inside.

Let me guess, where you leave there are "serious" blinds outside the windows that help keeping sunshine out. I wonder when Central Europe will start installing them.