> The big difference is because of air conditioning and baseboard heating (...)

Which makes you wonder why there is not as much high-profile attention on A/C (and to a lesser extent electrical heating) as being a problem worthy of rethinking by Silicon Valley (perhaps even ahead of solar, in North America).

It might be (it is) anecdotal, but as someone from Europe it struck me odd how much Americans love their A/C. Too much, in fact. Almost everywhere I went it was too cold. Somewhat like in SE Asia. That might be the answer to high energy use.

Another anecdote: I live in Belize and my girlfriend runs a hostel, and we can always tell which rooms have guests from the southern US because the AC will be set to 18C (~64F). For some reason northerners don't tend to do this, I assume because they don't use AC as often at home. The Texans I know are the worst. They make their apartments so cold I need a blanket if I'm going to stay for a movie, and they sleep under massive down comforters. In the tropics! It's so maddeningly wasteful. I rarely use my AC and sleep under a single top sheet with no discomfort.

I live where it tends to get hot and humid (not tropics humid though), but turn on A/C only if it's really unbearable at night. Even then, at most 5C difference. Usually, single top sheet, as you've said, a cool drink and maybe a fan is enough. I understand that humidity is tough though, but one can get dehumidifying alone from A/C or a standalone dehumidifier.

For Americans, mostly read Texans or maybe Southerners more broadly. A lot of us joke that the hotter the climate in a US state, the colder they tend to crank the AC.

That can't be good for health! SE Asia like to do that too. I joked that tropics there were a sham since I had to wear a jacket all the time because of the polar-like A/C.

It's worth noting that temperature control is only half the equation. In places like Houston, A/C plays a big part in controlling indoor humidity as well(for both comfort purposes and to prevent mildew from growing all over everything).

There's other (read: more efficient) ways to control humidity than using an A/C. Including making buildings more "airtight" so the dampness doesn't leak into the house (as long as you don't open doors/windows too much, of couse).

I have the same experience in both US (mostly Raleigh, NC) and China; but China has got better over the last twenty years, possibly because air conditioning is no longer an unusual thing in the big cities so it being cold indoors is not such a status symbol, perhaps.

There is quite a bit of work being done on solar powered airconditioning. I experimented myself with this about 10 years ago using two back-to-back Stirling engines with the first powered by the sun and the second being run in reverse to cool a working fluid.

It's an interesting field, you'll learn more about Carnot cycles and thermodynamics than you ever wanted to :)

A climatization using DC current from capacitors charged with solar panels might be more interesting in mild hot regions.

If I understood well AC is optimized for carrying current on long distance with minimal loss. But most electric devices use DC. They need an AC to DC convertor with some energy loss.

Solar panels produce DC and is usualy converted to AC with some loss. Then, in most electronic devices, this AC is converted back into DC in the device power transformator.

What waste of energy. Shouldn't we do something about this ?

> What waste of energy. Shouldn't we do something about this ?

Most devices which operate on DC (e.g. computers, TV) have a switching power supply, which is around 90% efficient. So for a computer drawing 100W, only about 10W is lost in the conversion of AC to DC.

Larger appliances such as microwaves, ovens, and air conditioners will use AC directly without conversion to DC (except maybe to power the control electronics).

> But most electric devices use DC.

Yes, but no national grids are DC. There is a lot of interest in using high voltage DC (HVDC) for long distance transmission (and wind farms), since you don't have to expend energy to generate and maintain the sine wave (and your collector field electronics are simpler), but the customer connection is always AC.

With the insane amount of money invested in delivery to homes as 110/220VAC, no one is going to start selling DC devices. Even in regions where this is no electricity and people use off-grid systems, the economies of scale mean that DC appliances such as refrigerators are often 200-400% more expensive than their AC counterparts.

A lot of research has been put into DC distribution, but the main issues are:

- Devices still require a DC/DC converter to step up or down the distribution voltage to their operating voltage. This converter is again not 100% efficient

- High voltage DC is deadly (your muscles will contract instead of releasing, so if you touch a cable you're dead)

- Low voltage DC requires thicker wires, meaning higher cost for distribution

Source: work for a utility company

Another factor is that high voltage DC step-down is significantly harder than AC step-down, especially once you get into the 100's of KV. With AC that's relatively easy, transformers are passive components, very well understood and can be made for extremely large power levels without getting into exotic engineering.

Baseboard heating, if it's the same thing as radiators, are the norm in central and north Europe IME.