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"Isn’t air conditioning in temperate climates an unnecessary waste of energy? ... wouldn’t it be more efficient to just open a window instead? "

Good luck with that in Florida. Open a window, it gets hotter.

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The article is talking about temperate climates, whereas Florida is humid subtropical in the north and central parts and tropical in the south.

In temperate climates, the temperature outside might be just cold enough, but not too cold, that "opening the windows", or something equivalent, might be a viable strategy.

The woman who is working on it is based out of USC, and in Los Angeles I think this would be extremely feasible - many buildings don't even have heat or air conditioning and generally only get hot based on the position of the sun, since there's no humidity to trap heat.

Definitely not a great idea in Florida for sure, but for Southern California I think its pretty compelling

This is still a good point- Wisconsin or Minnesota are actually in the temperate climate zone. These states might be -10 F in January and 102 F degrees in July. Both heating and cooling are necessary, regardless of their location in the temperate climate zone.

It might be idealistic to expect that technology like this could eliminate the requirement for HVAC entirely, but a more achievable goal might be to increase the number of HVAC-free days by 10-20%. That would NET a significant energy savings.

Good luck with that in most of the country.

Not in a well designed house, actually. I lived in Cuba, and in all the older houses it was quite cool during the day, if the windows were open.

I have no idea how they did it. This was mostly in coastal areas, so there was much wind. But it even worked in inland areas. The windows did not let in much light. There was usually no air conditioning, and inside was generally much cooler than outside.

In any modern buildings, air conditioning was required. I also expect this system might not have held up in the warmest summer months.

Sorry, but this sounds a little like nostalgia colored recollection. There's nothing magical about old architecture. Yes, some designs will stay cooler than others, but you're not getting anywhere close to an air-conditioned home in a Florida summer using old designs (barring absurdities like stone castles).

Florida is similar to Cuba. If you own a home located close to the beach, you're in good shape. You can leave your windows open all winter, and most of the fall and spring. As you move inland you lose the ocean breeze cooling effect very, very quickly though.

I grew up in a turn of the century bungalow home about 3 miles from the beach on the east coast of Florida. The home was built, and lived in, by a contractor who developed much of my home town in the 1900-1915 time period. The homes had many windows with long-ish eaves (for shade) so you could take advantage of the breeze. Back in the early 1900s, that was the only option you had.

Growing up, we only had a window unit air conditioner, and my parents couldn't afford to run it much, so I can personally attest to the difficulties associated with living in South Florida with no air-conditioning. It was never "quite cool" (by air-conditioned standards) in our house during the summer, even though the home was designed specifically for the environment. For most of the day it stayed cooler than it was outside, but on a cloud-free summer day, there was no relief, inside or out.

I'm not saying we shouldn't use innovative techniques to reduce energy usage, but I am contesting the idea that you can build an above-ground zero-energy home in Florida.

In tropical climates such as Cuba's thermal capacitance via masonry is a feature of Colonial architecture (and not one typically available to Florida's stick framed bungalows). Another feature of traditional architecture is high ceilings to take advantage of convection - something not uncommon to Florida's bungalows from the early 20th century.

This was 5 years ago and one year ago, so it's not pre-revolutionary nostalgia. I might be wrong on how well it worked inland, but I remember feeling cool no matter which city I traveled to.

This was October to May, so like I said, the system may break down in summer. It was still warm through those months compared to what I know in Canada, but I know summer is warmer still.

Brudgers makes a good point about the thermal capacitance of masonry below. If you spent much time in old, stone/brick/masonry buildings, they'll feel significantly cooler.

Unfortunately, you correctly observed that October through May is an entirely different animal in this region. All the windows in our home are open currently. We get many opportunities like this through the end of February, tapering off through March and April. By May, things in Florida start to heat up. Most could manage it, but I wouldn't call it comfortable.

In June through September, you can sit on your porch at 10 PM and sweat will stream down your face due to the heat and humidity. It is an insufferable burden to go without air-conditioning in this place during the summer months.

I also suspect that Cuba, being such a narrow strip, and having significant elevations in areas, has a more temperate climate than flat, hot, and wet Florida.

Were the walls solid concrete?

I think so, but I can't be sure.

Solid walls with a high thermal mass could have been moderating the temperature by themselves responding slowly to temperature change.

Florida is not in a temperate climate.

exactly. the skin doesn't just "breathe", there's energy being spent in order to heat or cool the body down, as a reaction to the enviromental temperature.

buildings spend energy to cool down/warm up because the outside temperature is unfavorable. Can't see how opening the windows would help

add to that most buildings are not designed with good air flow in mind. While my house, built in 2006, has a great HVAC system complete with returns in all rooms no real thought was given to how air flows through the home from the outside.

This is evident by some rooms feeling stuff regardless of open windows and others just downright unfriendly to anything loose. Toss in dark shingles (brown or darker) and a lack of large trees and most modern homes are not really habitable in summer without air conditioning. Fortunately I have ceiling fans in all rooms I spend time in but I wish architects for regular housing would spend more time with making a home livable with natural movement of air.

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