I would disagree with new houses not considering ventilation. There are set building standards (ASHRAE 62.1, 62.2, and ISO standards) that have been around for a while that specify how ventilated spaces should be for given use cases. There’s a more recent trend to evolve these standards to take into consideration non-hazardous levels of particulate matter and gases that still show cognitive impairment—-I’m currently exploring this topic area for my PhD work.

What we’re seeing, though, are tighter building envelopes so that the structure is thermally efficient. However, with a tighter envelope, active/natural ventilation systems becomes even more important than in older structures where there is some rate of natural air exchange with the exterior through building cracks and terrible (by todays standards) windows.

There are companies coming up that are looking at “Personal Comfort Systems” and there is a fair amount of active research in this area (ex., https://cbe.berkeley.edu/research/personal-comfort-system/). It’s an interesting space since you have essentially two knobs to play with: (1) a persons actual heat exchange with the environment and (2) a persons perceived heat exchange.

Modern building codes do carefully consider ventilation, but I think a lot of knowledge and tradecraft have been lost.

If you're lucky and live in an older house of the correct design from just before A/C, (most of the oldest two-story single family homes in Berkeley, FWIW) you might notice that some of the internal walls stay well below room temperature during the summer.

The buildings typically have pier and beam foundations, and the cooling walls have passive draft ways that pull cool air over the ground under the house and up against those walls. This is great in the summer, but not so much in the winter. I don't know how they use convection to pull cold air up, or how they prevent moldy foundation dirt air from permeating the house. I've heard there are some pretty clever designs, but (of course) they're hidden behind walls.

Anyway, our modern house is one story, and has an intentionally-uninsulated concrete slab on grade foundation, so we get a similar effect. (Passive solar heat keeps it toasty in the winter.)

We usually have our windows open, but we also over-insulated the walls (for noise and efficiency), and have a tight building envelope, so the heating/cooling bill is tiny.

(Edit: I bet they vented the walls into the attic and under the floor. That'd create a strong updraft in the summer (out the attic vents), but (if the attic is well insulated against the rest of the house) not in the winter.

That's for keeping air safe for humans, not using passive ventilation as a replacement for HVAC equipment.

Glad to know about those new standards. I'm talking specifically about Brazil, though.

I'm not aware of such standards over here. Maybe they exist but aren't being followed, or maybe they are deficient.

I had family members who lived in a home in the deep south that was built before air conditioning was common. It had a large fan in the ceiling of a central hallway that vented the air from the inside the house out through the attic. This was an industrial grade fan that moved a huge volume of air.

At bedtime, they could open the bedroom windows and turn on the fan and a stiff wind would blow in through all the bedroom windows in the house.

That fan, along with window awnings and tall ceilings, really made a difference in how often they needed to use air conditioning, even near the Gulf of Mexico.

We had a whole-house fan like this in Sacramento. It worked especially well there because (1) it was not humid, and (2) the temperature at night was much lower than in the daytime. It might be 100° during the day, but it would be in the 60s at night.

Fans like this aren't nearly as effective if either of these conditions is not met — then you're just pulling in air that is somewhat less uncomfortable each night, instead of getting truly refreshed.

As mentioned, this was right on the Gulf of Mexico where it was both very hot in the day and very humid all the time.

In the early summer, the temperature dropped from the upper 90's in the day to the low 70s at night. In the worst of the summer, the temperatures were only dropping to the 80's, and they did use the air conditioners then.

However, that fan moved so much air that there would be a stiff wind blowing across the beds all night, and that cool humid wind would have you under the blankets in no time.

I.have one in my house, it is going to be removed in the near future. It works good some days, but modern ac is still better. When we use the ac it lets hot air from the attic in, and worse all winter it is letting cold air from the attic in. The thing can really be insulated.

There is a lot about this house that needs to be updated to modern energy standards and getting rid of that fan is on the list. Overall it costs far more than it saves.

>When we use the ac it lets hot air from the attic in, and worse all winter it is letting cold air from the attic in.

The one in my relative's house had louvers that would open when you turned the fan on and then close when you turned it off, so it sealed itself off when not in use.

They saved a fortune by not having to run the ac all summer.

Those louvers don't seal very well at best, and even sealed they have no r value so they are not very useful. They can save ac in summer, but IMO not enough

Actually, they did seal well, and the savings were quite significant.

I installed a whole-house fan in our place in San Jose. That plus ceiling fans in each bedroom meant we could go all year without A/C. This was the Bay Area though.

I had remembered whole-house fans when growing up in Kansas — many of my friends had homes with them. They could be noisy but really did make for a nice house breeze in the evening.

My childhood home, in a mid-century California suburb, used the same fan arrangement. Incredibly effective... if also very noisy.

what state and what was the average humidity, or even better dew point?

I personally find fans made very little difference for me in humid climates.

GP and GGP are describing different methods of cooling:

Sitting in a breeze does two things: 1) Allows your sweat to evaporate more quickly, and that evaporation is what causes most of the cooling effect. It's not very effective in high humidity because your sweat won't evaporate very easily. Evaporative coolers / swamp coolers work off this same principle. 2) Sitting in the still indoor air your body heat warms the air around yourself and you end up sitting in that pocket of heat. Just about any airflow stops that, which is why air circulators (fans that are meant to point from one end of a room to another instead of directly on a person) work to make a room feel a bit cooler.

Running the attic fan at night with open windows can have similar effects as above (especially the air circulator), but on top of that it's for pulling in the air from outdoors after it's cooled off at night, and expelling the warmed-up air that accumulates near the ceilings and roof. You'd want to close windows in the morning so the warmed-up air doesn't get pulled in and replace all the cooler air.

Fans don't improve comfort as much if humidity is high, because the airflow doesn't cause as much evaporative cooling on the skin. So you need a temperature gradient to get a good effect. Attic fans are a good example. The attic tends to get hotter than the outside air when the sun is shining, and the fan helps equalize.

There are air conditioning robots that follow a person around blowing cold air on them.

They aren’t very practical, but could be more efficient than cooling an entire building for one person.

And instead of cubicles, perhaps we could have insulated ice baths like athletes use after games. You sit down in there and pull a tray over the bath with your keyboard, mouse and monitor. You can soak your hands to keep the inflammation down from the repetitive stress too.

The energy savings from spot cooling with fans can be incredible compared to AC. A garage AC unit consumes ~1300W while a 20” fan consumes about ~150W.

My startup, Following Fan, has built a person-tracking 20” fan that uses computer vision to automatically stay pointed at the user as they move around. This technology provides the location agnostic benefits of AC with the energy consumption of fans.

But ac also reduce humidity. Fans just blow air, at high humidity and high temps the fan would be useless?

You’re right that fans don’t affect humidity and are less effective in extreme heat.

However, there are many places such as garages, airplane hangers, and large warehouses where AC is impractical due to a lack of insulation and the need to open large doors to move vehicles or goods in and out.

In those environments, fans are about the best cooling solution you can get. One big issue with traditional fans though is that they just point in an single direction or oscillate back and forth regardless of the location of the user.

Yeah, this is a big one for people in humid climates.

Here, it doesn't get that cold in the winter, but the house gets absolutely balmy and gross feeling. I have to turn the AC on just to get some humidity out of the air, despite it being in the 60s or 70s.

I have a dehumidifier also, but it can't do the job alone. It's really weird seeing how much water it sucks out of the air.

I live in an old shotgun double in New Orleans. A lot of the features designed for airflow have been fucked up by “modernization” - most of the windows are permanantly closed due to window AC units, transom windows above the doors between rooms are painted shut with the hinge support stuff gone, etc - but it’s still really amazing how much colder it is than the outside. It is designed to shed heat in a ton of ways and it’s so much better at it than the newer house in the same city I grew up in.

Just curious, what part of the world do you live in?

I've lived in cities where we experience anything between below zero to 120F throughout the year. I couldn't imagine not having AC/Heating in those areas even with more efficient ventilation/insulation.

Mainer checking in. Wednesday afternoon it was 70F. The next morning it was 5F Friday a snowstorm. Today -2F in AM.

We all just dress in endless layers.

Worth it for the lobster rolls though, right?

How, that's a huge temperature gradient.

I live in Fortaleza, Brazil. Temperatures here are very stable along the whole year (78F - 90F, it rarely falls out of this interval).

I'm not advocating this no-AC model as a general solution though. I'm aware we're a bit lucky here. I used to live in Sao Paulo and temperatures vary more wildly there, sometimes within a single day.

Any temperate area on the planet will easily have 90-100 degree swings throughout the year. I used to live on the US East Coast and a summer high of 90-95 and winter lows of 0-5 were common my entire childhood. I moved to the midwest in the early summer and it hit 100 more than once, and it's been below 0 multiple times this winter already.

We are near to the equator here. Seasons don't work the same. Here they call the 3 rainy months "winter", and the rest of the year is summer.

And the temperature gradient I've mentioned is correct. No noticeable changes along the whole year, I'm sorry.

> No noticeable changes along the whole year, I'm sorry.

It does sound kind of unpleasant, but I imagine you get used to it.

Yes, we get used to it, not unpleasant for me, at all.

But it changes the way you live. Compared with lives of friends from Europe, I notice that theirs has a bit more of a "structure" and predictability. E.g., hang out more in the summer, doing more reading and writing more in the winter.

I think I would enjoy that. Of course I could plan my life based in months instead of seasons, but it's not the same, especially considering that people around me wouldn't be following that same plan.

Consistent year-round temperatures is something I thought I'd want right up until I experienced it for a while. Turns out I like having the variety of seasons. I love snow, but not all year. I love the leaves falling, but not all year. I love Spring thunderstorms, but not all year. I even love 110F heat waves, but I'm glad when Fall arrives :).

I grew up in the Midwest and lived in SF and LA for a few years each. I definitely missed the seasons changing and appreciated them even more moving back to the Midwest. Lack of seasons really messed with my sense of time, like: "Oh that thing we did last month...oh woah that was six months ago??"

You can come back to the SF area. Thanks to climate change, we have four seasons now:

Not enough rain / sunny and 50 F

Sunny and 70F; green plants

Sunny and 90-105 F; brown plants

Red Skies, ??? F; black plants / red embers

Yup. I live two hours north of Boston; our coldest winter temp most years is -25, and we usually just touch 100 one day in the summer.

> The new houses are designed with zero consideration about ventilation, designers seem to take for granted that you are going to buy an AC system.

These are two separate problems.

In the ideal situation, you generally want the house to be fairly air tight and condition the air for (a) temperature and (b) humidity. Each of (a) and (b) are taken care of by different mechanical units: one is monitored by a thermometer and the other by an hygrometer. The latter triggers a stand alone dehumidifier:

* https://www.aprilaire.com/whole-house-products/dehumidifiers

For fresh air you have an HRV/ERV, which brings outside air (through a filter) into the house (usually to bedrooms), while at the same time blowing out stale inside air (usually taken from bathrooms and the kitchen), with the two moving through the unit so that the outgoing air tempers the incoming air:

* https://www.ecohome.net/guides/2276/choosing-between-an-hrv-...

You still have opening windows, as they're mandated for emergency fire exits.

This is exactly the problem with newer design and construction philosophy. Its premise is that we will use mechanical systems, and then try to make these mechanical systems more efficient such as improving insulation, using multi-stage condensers for the AC, etc. This is epitomized in the passive house concept.

In contrast the older philosophy is that natural ventilation is good enough, so we design houses to improve that, such as strategic placement of windows to allow cross ventilation, use high ceilings to allow heat to rise, etc.

The original article is squarely in the second camp.

> In contrast the older philosophy is that natural ventilation is good enough, so we design houses to improve that, such as strategic placement of windows to allow cross ventilation, use high ceilings to allow heat to rise, etc.

Yeah, and all those open windows bring in pollen and dust. Yay! Hope you have a good bug screen as well.

Of course if there's high humidity then all than ventilation may not help because the air is already saturated so your sweat doesn't evaporate so you're not cooled.

Natural ventilation could be great if the conditions outside are exactly what you want them inside as well. But if the outside is too hot or too cold or too humid then what are you going to do then?

Build Tight, Ventilate Right:

* https://www.energy.gov/indianenergy/articles/build-tight-ven...

A 5000 sq. ft. / 500 sq. m. house can be conditioned with as little as 2000W (a hair dryer):

* https://www.youtube.com/watch?v=_vul4vMFdkA

Modern (post energy crisis) houses have 10-100x higher indoor air pollution than the outdoor air. CO2 concentration is also an issue.

Older houses didn't have those issues, but energy consumption and humidity regulation were nightmares.

Removing drafts created and solved many difficult engineering problems.

I think having a tightly sealed house with lots of openable windows is a good solution. Most days, you can hopefully leave the windows open during the day and/or night. On smoky/hot/cold days you can run filters and ac/heat.

In some countries, it's common to open all the windows for 15-30 minutes, even on really cold/hot days. There's basically no thermal mass in the air (vs. the contents of the house), so it uses much less energy than you'd expect, and the house returns to temperature quickly. However, it greatly reduces indoor air pollution (by roughly an order of magnitude), including dust and pollen.

You could get a similar effect with an air exchanger, especially in Alaska, like in your link.

However, those don't usually do much to help with humidity entering/exiting the house, which is the main drawback of opening the windows for 15 minutes.

2000W sounds like a small amount of energy until you realize modern heat pumps have coefficients of power between 5 and 10. So, that house could leak 10-20KW of energy on average, and still meet the 2000 watt goal. (Assuming they installed a heat pump, which they should have before paying for ultra high end insulation.)

> Most days, you can hopefully leave the windows open during the day and/or night. On smoky/hot/cold days you can run filters and ac/heat.

I'm in Toronto, Canada: our winters are -10C and our summers are hot-humid 30C.

* https://en.wikipedia.org/wiki/Toronto#Climate

Leaving windows open is not the preferred option for most of the year (though I grew up in a house with A/C, and only first experienced an abode with in in my 20s).

Further, more places are getting bouts of extreme weather:

* https://en.wikipedia.org/wiki/2003_European_heat_wave

Heating and insulation need to be a system. You can't install the heat pump first as it needs to be sized to fit the energy loss of the house.

People lived before 1902 and the invention of compressor-based air conditioning.

People also died a lot back then.

Even today heatwaves in Europe kill a lot of elderly as air conditioning in homes isn't common

People lived before 1945 and the wide availability of penicillin/antibiotics. A lot more folks died from infection as well.

Not in all the places and densities that they do today.

My personal preference is deeply in the natural ventilation camp, and the typically delicious air we have in the Bay Area is a boon to my wellness. I leave the windows mostly open 24/7 three seasons, and in the winter I partially open them during significant portions of the day. It’s wonderful.

But during the worsening wildfires seasons, I must tightly seal and air purify my apartment for weeks straight, and had to buy an air conditioner that I run during the day. The stale air is unpleasant, but unavoidable.

How idiosyncratic are my preferences and environmental circumstances? Are any architects working on house designs for me?

I think a passive house design would be excellent for you.

Highly insulated, air tight (but vapor permeable) building envelope. Constant intake of fresh air to bedrooms living rooms, filtered and passed through a heat exchanger to heat or cool it with air exhausted from kitchen and bathrooms.

They generally cost about ~25% more than a standard code-built house (unless you want a lot of windows), but cost much less to heat and cool. They're also more comfortable and have less pollen, dust, and even insects.

> How idiosyncratic are my preferences and environmental circumstances? Are any architects working on house designs for me?

Very. SFO is is in climate zone 3, and the Bay Area is a micro-climate unto itself:

* https://basc.pnnl.gov/images/iecc-climate-zone-map

Do you think Florida or Texas could do the same thing? Minnesota or the Dakotas? Anywhere in Colorado or the New England region?

An architect will design anything you want, as long as it meets code.

I think your preferences make total sense. Though I have little experience with wildfires. Would an air filter help?

For my own eccentricities, I have the bedroom window open slightly while sleeping, closed when awake.

During the winter, when inside I wrap up in warm clothes, thermals, scarf. When exercising outside I wear only one or two layers. I call it the 'Winter Paradox'.

> How idiosyncratic are my preferences and environmental circumstances? Are any architects working on house designs for me?

You must have quiet neighbors if you can stand leaving the windows open all the time.

I live in a mid density city with a nice ambient hum. Indeed the neighbors in my building are respectful, as are the neighbors on either side. But I think the ambient hum is key to the peaceful atmosphere, when living in a city. The biggest threat we’ve experienced in terms of noise is blue jays that I finally staved off after months, by occasionally assaulting them with a super soaker. Other birdsong is pleasant, I hear some right now and open the window wider.

I say this as somebody fairly particular about my comfort. I can’t stand interior transformer hums for example.

Respectful neighbors in the Bay Area?

Which city?

The best neighborhood in Oakland (which I will not name).

Indeed. Speaking about hot and sunny cities like mine, besides strategic placement of windows I would also mention barriers to direct sunlight over the walls. Simple barriers can improve inner temperatures sensibily and costs no energy, but most projects don't take that in consideration.

Jesus, here there are even buildings importing those "glass wall" concepts, which makes total sense in climates like European's and north American's, but makes absolutely no sense in sunny cities -- you just end up aggravating the greenhouse effect and having to rely more heavily on AC. Everything because of façade aesthetics.

It doesn’t even make sense in North America - the glass walls make it very unpleasant in summer, even in heavily air conditioned buildings, even in moderate climates (California). It’s like working out next to a space heater, with an AC unit blowing on your neck.

> These are two separate problems

I've learned a lot about US climates and their notion of ventilation, here at the comments I got.

I hope you guys also have found interesting that, in some other parts of the globe, ventilation and air cooling are two very interconnected concepts. And also that, in climates like ours, relying solely on AC while not taking advantage of the cooling properties of moving air masses means waste of energy.

'Traditional' ways may break down in more extreme situations:

* https://en.wikipedia.org/wiki/2003_European_heat_wave

* https://www.bbc.com/news/world-europe-49628275

Most of western Europe (the part most in Europe reading this are from ) have mild climates compared to the US. Of course the US is a large country, and so there are more climates in discussion. What works well in Europe often doesn't in the US.

Of course one size fits all codes don't help. What works well in Europe will work someplace in the US, just not everywhere

Ventilation doesn't help much with humidity, which frequently overlaps with the heat.

I get by without AC in the northern Midwest, but I'd be inclined to get a window unit if there was more than a few uncomfortable nights a year.

Uhm.. for me it helps, and A LOT. Surely there are more factors involved, which I'm not aware of. I'm talking from Fortaleza, Brazil. Maybe the sea is bringing cooler air. I really don't know, I only have these pieces of empirical knowledge and my experience is very narrow, basically limited to this city.

A large body of water near by certainly has a moderating effect on temperature.

I looked up the climate data for Fortaleza, and compared it to my town (random US city, about 35 degrees northern latitude, so not super far south or anything.)

Our average daily highs in summer are only about 1 degree (C) lower than your RECORD highs... your averages are about 9C lower than ours.

Without AC here it would be...supremely unpleasant, and well other the threshold of danger for anyone with any sort of medical issues.

This is something that I don't think Europeans appreciate. Most of the USA is way hotter and way colder than most of Europe

Our air masses are probably cooler than yours because of the sea, I'm not sure. There seems to be more factors in operation.

It can, though has limits to how hot/wet it can help with - see figure [0] for Celcius and [1] for Farenheit which show the accepted climate-science approach mapping appropriate techniques for achieving comfort at various temperatures/humidity.

Ventilation is actually best for hot-wet climates where hot-dry climates (common through much of the US) are usually better dealt with through thermal-mass/thermal-lag as typically the nights are cold (in hot-wet usually the nights are hot).

[0] https://www.researchgate.net/profile/Kiyan-Vadoudi/publicati...

[1] https://leetammy.files.wordpress.com/2012/11/blue-psycho.jpg

Homes should include a central dehumidifier. I believe they’re more efficient than running the AC since there’s no net temperature change?

This depends on the climate zone you’re in. In drier climates, some HVAC systems are actually humidifiers which blow the outside dry/hot air through a wet membrane (ex., desiccant) and blow out wetter/cold air.

Yeah, I have a humidifier attached to my furnace and my house is still often dry enough to make every piece of furniture extremely staticky

Running a dehumidifier here in the summer would be cruel and unusual.

I am in New Mexico and am thinking about a central humidifier. It’s super dry and especially during the winter I have massive problems with dry skin.

IMO the real solution is building materials with high heat mass (e.g. stone), and architectural designs which allow for passive cooling. This exists already, but can be expensive to build.

Lived in a stone house when I was younger. It was amazing at keeping us cool or warm for long periods when the temperature shifted.

In current apartment heating doesn't work properly until days after its gotten cold, and it's instantly too warm when it gets warm.

AC is very uncommon in Scandinavia, and we have 85-95% humidity in my area year around.

An alternative is heating panels that emit long IR. These allow you to maintain a lower air temperature and still be comfortable when they're shining on you.

How even is that warming you get from them? I find it very uncomfortable to sit outside at a restaurant where they have heaters. One side gets roasted and the other is cold.

There's such variety in comfort. Being too warm on one side and too cold on another is one of my favorite ways to be.

I too love campfires.

The same way the sun warms you when you walk out of the shade. Air temperature is the same but you feel warmer. Long IR is completely different than conventional heating elements that can only heat air.

Lathe and plaster works as well.

Ventilation is so underrated. There is not only the obvious benefit in reducing electricity usage, but it helps with noise (AC doesn’t run as often), dust (free flowing air keeps it from collecting in air-flow deadzones), mildew (as with dust, air flow keeps moisture and humidity from concentrating in one spot), and the longevity of your appliances (cumulative effect of all of the above).

In Europe still today AC usage is at less than 5% of all households. Sure the US likely has more cities in really hot places, but ACs are still generally an American thing

They say air conditioning settled the west.

Desertification in that area is starting to roll that back though. Never-irrigated ranches are drying up. Without argiculture, the towns die. The ecosystems don't recover, even in places where the people are gone and the buildings have rotted to dust and blown away (too hot / no rain).

This must have been how people felt when the Sahara turned into a desert. I can't believe it's happening so fast. (Towns that were populated 20 years ago are completely invisible now.)

Not to mention the onset of a new Dust Bowl[0]

[0] https://www.youtube.com/watch?v=THSm-I790H0 (PBS Eons vid about it)

There is an article on the notechmagazine site about ancient air conditioning here: https://www.notechmagazine.com/category/air-conditioning

Really interesting architectural technologies came out back in the day.

Ventilation and air conditioning are two very different things. Unless it’s a central unit, the AC will be reusing the same air. In order to not die of lack of oxygen you need ventilation as well.

Interestingly, the articles I find about ventilation are indeed concerned about air quality. However, in my country, at least in the cities I've lived on, the idea of ventilation is mostly associated to cooling indoors (with air quality being a desirable byproduct). Maybe the differences between our climates led to differences between the concepts behind the same word. Or maybe there's a better word in English to express what I'm intending to (sorry, English is not my mother language).

I think you can only separate them in radiative systems. But otherwise, a modern commercial HVAC system has a degree of mixing the air from the outside world to reduce gas and particulate concentrations. So in some systems, the HVAC is the ventilation system but when only ventilating, the flow rate is stepped down and the conditioning system is inactive.

In traditional Iranian design, they would paint a chimney black to generate a constant updraft. It works in dry areas.