Disclaimer; I live in a very moderate climate. So I don't know how this would scale to hotter cities.

My home is equiped with what would translate to a "heatpump". Its a system that uses the warmth deep in the earth to help heating up the home in the winter, but also cools it down in the summer storing excess heat in the well drilled underneath the home or garden.

What it does in summer is basically run cold water through the underfloor heating system.

We've had some very hot days for our climate recently (35 to 38 degrees centigrade, which is around 95 to 100 Fahrenheit) and the temperature inside remained steady at a comfortable 23 degrees centigrade (around 74 Fahrenheit).

The system uses a lot less energy than air conditioning.

This is a geothermal heat pump.

There are traditional outside air conditioner units that run in reverse which use heat in the air, as well.

How cold is the water used to cool the house? If the water temp fell below the dew point, you would have a condensation problem.

> It would be so easy to make every building comfortable.

Every time there's a thread on air conditioning, we get smug comments like this, usually from places where the climate is so comfortable to begin with that air conditioners are the least necessary. Okay, Los Angeles needs them two or three months a year. Anyone from San Francisco, on the other hand, forfeits the right to talk about air conditioners in my opinion.

I'm sitting in a major metropolitan area in Asia. The temperature right now is 39'C (102'F), and can easily go over 45'C (113'F) in the sun. The humidity fluctuates between 50% at midday and 90% at night, and the temperature remains above 30'C (86'C) through most of the night, too. I would love it if you could make every building comfortable under these constraints. Hint: increased ventilation only brings in more heat. Any cooling solution that relies on evaporating H2O does not work, either, so don't bother bringing those Kickstarter gadgets here. Most of the old world is in the same boat. Coastal California is the exception, not the norm.

I think the GP was referring to _every building in Los Angeles_, not every building in the world. You do make good points about how weather elsewhere would make it very difficult to handle without AC.

Yes, absolutely only referring to buildings in LA. Shade and airflow don't help if the air is hot and humid.

The only thing worse is experiencing the same conditions, but being a half-day/day drive away from these places.

Hell, we run our air conditioner sometimes just to get the humidity down below 50% indoors.

In Andalusia, Spain, the weather can get really hot and you rarely see AC in houses (it's still common in buildings such as malls and hospitals, for example). I am sure there are many features of Andalusian architecture that would be applicable in LA and other places in the US.

You are right, and it is ironic that the historic building style in those regions probably was in the Spanish tradition of the early settlers.

This summer has been far more humid than I can remember. I'm glad I had my AC repaired in April after having it not working for the last three years. The electric bill has been ugly though.

Los Angeles has very pleasant summers by East Coast standards. Many even fairly well off homes do not have air conditioners.

It's not great, but it's a lot better than lots of more northern cities like Boston. I literally cannot sleep in Boston during the summer without air conditioning.

In my only experience with the East Coast (CT), I also noticed the general lack of air conditioning, even in homes which to my Midwestern mindset surely had to have state of the art HVAC systems (they didn't). Oh how I long for 70-degree summers.

That is the general appeal of these places, for sure.