If you have a smallish house and a centrally located fan, a whole house fan is amazing. The rooms get cooler and the attic gets cooler too. You can shut doors to make a specific room cool in minutes. Seriously one of the best things you can do to a house imo.
Before air conditioning became accessible, large window fans (like the Homart Cooler - which I own) were very popular in the middle of the country with hot days and cool night (e.g. St Louis).
Not as good as placing one in the attic, but a really effective alternative that can be carried from property to property.
The attic getting cooler is one of the most important aspects of a house fan. The thermometer in my attic regularly reads 20° F above the outside temperature. Blowing that huge pocket of hot air out makes a huge difference.
My last house had a hot attic with a window at each end - I always intended to set up four fans on relays, two in each window, so it could blow cool air in from either end, to take into account which side was cool and shady (and night they could just switch off to to reduce wear).
In case this ever comes up again... they have attic fans that are activated via temperature so that would your overnight issue and I'd imagine the gains by rotating which side is pulling in air is negligible compared to the effort to control it.
If a hot attic is making your house hot, then you need additional sealing between the attic and the house, or additional insulation on the floor of your attic. Attic spaces are normally vented so that they are kept at outside temperatures. In the winter, attics are regularly 30 degrees below the inside temperature. A 20 degree difference in the summer shouldn't be a big deal. That said, plenty of people will sell you attic fans or other gizmos to moderate attic temperatures if you don't want to fix the insulation/sealing problems.
Whole house fans do help a lot in pulling cooler outside air into the inhabited spaces.
My home isn't really set up for a whole house fan, but what I'd love to do is find some way to divert the HVAC blower fan to blow all of its output outside.
It should have the same net effect as far as I can see. I'm curious why systems don't have an option to do this.
Some do, but it's inefficient on a couple of levels. First, the damper to divert air to the attic will never seal perfectly (or at least it won't a short while after it's lived in your attic) so you'll always be losing some cooling to your attic when your AC runs. Secondly, the volume of air an AC system is set up to move does not come close to comparing with the amount of air a properly sized while-house fan will move. The blowers are just designed for 2 different roles...
Yeah, I realize the HVAC blower is smaller than an attic fan. It just seems like having a controlled diverter (blow air to the house /or/ blow air outside) could help draw in outside air when needed.
In my part of the country it cools off at night, but the wind typically stalls. At least drawing in some of that air could let me skip running the A/C compressor overnight.
Yes, but that doesn’t change the inefficiencies I mentioned, which are why it isn’t often done. It is done sometimes - I had a home with such a setup - but you’re much better off dropping a few hundred $$ on a proper whole house fan.
We have one whole house fan that cools 4700 sqft. During the day I turn on our mini-split in the theater and leave the door open. On the vast majority of 95F days the main HVAC doesn't come on at all. On days where it hits 100F, the main HVAC might kick on for an hour or so.
"If you have a smallish house and a centrally located fan, a whole house fan is amazing. The rooms get cooler and the attic gets cooler too. You can shut doors to make a specific room cool in minutes. Seriously one of the best things you can do to a house imo."
I just added a whole house fan to my home in the bay area and it works very well - the temperature drops by as much as 30+ degrees from daytime to night time here.
I really appreciate the simplicity of not having AC infrastructure anywhere in my house.
However, I have lived in other climates, like Minnesota, where the nighttime temperature does not drop much at all and I am not sure it would be worth the effort. If it was a box to tick for new construction, then sure - but I wouldn't go out of my way to add it to a house after the fact ...
This idea is older than one might realize. Ancient Persians and other Middle Eastern civilizations knew how to combine a windcatcher, or bâdgir, with a qanat, an underground channel, to create an effective evaporative cooler.
God, this reminds me of Paris 6 University, architect thought it would be awesome to create a fully open ground level, turning the campus into a square mile large windcatcher. Even during summer that's often too much air current.
Many people don't understand how effective Qanats are, but they were/are used to store freakin' ice in the middle of freakin' Iranian scorching desert - seen one near Yazd.
Big respect to the builders/engineers. It's 2400 years old
Just FYI: You seem to have been shadowbanned for quite a while. I vouched for this comment to let you know, because I didn't see anything obviously deserving such treatment.
Yes, impressive but the scale had to be sufficient - it wouldn't work well for a smaller residence. That said, a large enough modernized variant may work well for neighborhoods.
Since warm air can carry quite a bit more moisture than cool, this specific idea is likely to result in condensation as the cool outside air joins the moistened warm house air.
If the roof insulation is less than perfect, simply wetting the roof periodically will go a long way toward drawing heat out of the house.
If the roof insulation is good enough that this wouldn't work, you very likely don't have a problem to begin with.
In the Southwest it is common to use roof-top heat exchangers to warm backyard pools, but the same houses have A\C and may have solar as well (which incidentally shades a section of the roof), so I suspect “watering your roof” would not be terribly effective. Worth a try though.
Watering the roof should be quite effective, but rather wasteful if you are using utility/drinking water. If you have a way to collect rainwater, and recapture what runs off of the roof, it could be effective, but evaporative losses will be large.
A while ago a Low-Tech Magazine article discussing compressed air as energy storage got a lot of traction here[0][1]. One of the more promising approaches it included was combining the compressed air energy storage with heating and cooling solutions. This integrated approach should result in much higher energy efficiencies, since problems with one technology basically become solutions for another. Evaporative cooling could be yet another low-tech tool in the toolbox here.
Aside: that LTM article made me think of a complaint of a friend of mine on that the solar panels on his house are almost never at optimal efficiency due to temperature. At which point I asked him if active cooling of solar panels using heat transport + a heat buffer underneath the house + re-using said heat in winter might be a win-win solution for that - he thought it was a good idea but also too ambitious a project for him to undertake.
Shared all HN links with the author, hope he joins in on the discussion here.
These ideas are very cool, but I don't believe they will see succeed in the mainstream marketplace without price signals.
I also don't trust government bureaucrats to figure this all out, either.
A carbon tax basically would just reward good ideas in the market, and punish the bad ones.
However, almost no one supports it. You get some big figures like Musk and the economist, Mankiw; but both the left and the right of mainstream politics don't want it. The right doesn't want new taxes nor to particularly combat global warming; the left is ideologically opposed to market-based solutions and instead supports big government/power-grab solutions--specifically cap and trade.
TL;DR consider supporting a carbon tax if you like these ideas and want to combat global warming
The left is by no means a monolithic block in these respects. A lot of the left - perhaps not so visible in the US - are ideologically opposed to big government. Libertarianism started with an anarchist, after all (Joseph Dejacques; who criticised Proudhon - the "founder" of anarchism - for being a "mere moderate anarchist, liberal but not libertarian").
Lots of left-wing ideologies favour using market mechanisms this way, and I wish more would - you can want to use market-mechanisms this way whether or not you're for free-market competition in terms of valuation and trade of company shares.
Among the USA war media's most important tasks is the maintenance of the false binary. They've done yeoman's work recently: how else could one explain that mainstream progressive thought is now to constantly foment nuclear war with Russia? (I'll quote Chancellor Merkel here: "I think it must once again become normal for Russian and American presidents to meet.") Alternatively, how is it that the party of Lincoln is now prominently associated with Nazis? (Go ahead, tell me one of these observations is wrong...)
In reality, the two "choices" imposed upon us are Coke and Pepsi, two noxious compounds that require extended chemical analysis to differentiate. They both want more war, all the time, in every case, for whatever reason. The real reason, of course, is so that they may skim some of those sweet armaments manufacturing profits. No it's not a conspiracy. Important influencers know which side of their toast is buttered, but they are a small minority and they don't need to coordinate in secret. Everyone who doesn't revolve from bureaucratic post to public office to lobbyist to executive board to think-tank sinecure, is a mere useful idiot. If 10-20% of American voters ever learn about horseshoe theory, they'll be screwed. Therefore the media mentions that about as often as they mention e.g. Libya or Yemen.
So, it's little surprise that we Americans have no clue about leftist thought.
I was mostly with you until the "horseshoe theory" stuff, which seems out of place. If anything, "horseshoe theory" is a recent fabrication to reinforce the notion that the space outside of our false-binary choices are all invalid, and equally so. Social Democrats, Anarchists, and Nazis all get sort of lumped into the don't-even-think-about-it box together.
I'm sure it has been used that way! I'm thinking more about the areas of agreement that exist among people with different politics. Maybe we don't agree on the exact right destination for e.g. some $2T chunk of money, but we agree that it shouldn't be used to kill random people overseas. That ain't centrist! I occasionally lurk over at Caitlin Johnstone's site and I get a kick out of the "cross-ideological collaboration" she's doing.
The only place I used "liberal" was in a quote of Dejacques from the 19th century. Of course it's the "old" (rather: the one still used everywhere but in the US) meaning, as someone adhering to classical liberal thought.
> the left is ideologically opposed to market-based solutions and instead supports big government/power-grab solutions--specifically cap and trade.
Carbon taxes have a substantial base of support on the left (possibly more than cap and trade, whose base of support is more centrist.)
Now, carbon-tax supporters are likely to support cap-and-trade as better than nothing, but that's different than preferring it and opposing carbon taxes.
> Aside: that LTM article made me think of a complaint of a friend of mine on that the solar panels on his house are almost never at optimal efficiency due to temperature. At which point I asked him if active cooling of solar panels using heat transport + a heat buffer underneath the house + re-using said heat in winter might be a win-win solution for that - he thought it was a good idea but also too ambitious a project for him to undertake.
Yes, this idea has occured to other people. They are called PVT Solar Panels (PVT=Photovoltaic + Thermal).
High pressure compressed air storage isn't really practical for widespread home use. High pressure compressors require a lot of maintenance, much more than batteries. The moving parts and seals wear out and have to be replaced. Some lubrication is needed. And if you do it wrong there's a significant risk of fire.
You're replying (indirectly) to a linked article which cites 30 sources to make its case. Not saying that you're wrong, but it would be nice if you have some data to back up your claims.
The article is not peer reviewed, nor are most of the citations. And none of them go into the details of the cost and skills required for maintenance.
If you want data, go to your local gas supplier and talk to the technicians who maintain the high-pressure compressors. It's not rocket surgery but still way beyond the abilities of most homeowners.
> The article is not peer reviewed, nor are most of the citations.
Sure, the article is not peer reviewed. Neither is your comment. Dismissing the citations as mostly not peer reviewed is just disingenuous; the majority of them are from journals on energy, conferences on applied energy, and other relevant fields of research.
Using "the local gas supplier and the technicians maintaining high-pressure compressors" as an counter-argument is just as flawed, unless you're seriously claiming that they are more likely to be a source of peer reviewed knowledge about the latest developments in compressible energy storage than the work of the cited researchers.
Look, I'm not saying that this is ready for usage; the article itself ends with:
> In conclusion, small-scale compressed air energy storage could be a promising alternative to batteries, but the research is still in its early stages – the first study on small-scale CAES was published in 2010 – and new ideas will continue to shed light on how best to develop the technology. At the moment, there are no commercial products available, and setting up your own system can be quite intimidating if you are new to pneumatics. Simply getting hold of the right components and fittings is a headache, as these come in a bewildering variety and are only sold to industries.
But you're being dismissive of a technology in quick development without even engaging with the article.
House fans are pretty cool, but as someone who has had one before: be cautious of the airflow blowing out the flame on your gas stove / pilot light of various appliances.
It has only happened to me once or twice, and is a non issue if you choose which window(s) to open carefully.
That being said, we love our total home fan, and it's also great for clearing out various odors
Edit: if people are having campfires near your house you'll want to shut it off asap
This is true for gas heaters (actually it's usually a physical valve that opens on thermal expansion, not a sensor). This prevents a blown pilot from being a safety concern, but it's a pain to manually relight them.
I know of no gas stove that has such a feature, though.
Gas water heaters have this, as do older gas furnaces (any newer furnaces will have electronic ignition not a standing pilot).
For kitchen stoves, most have electronic ignition as well. For an older stove, the amount of gas released from an unlit pilot is not significant enough to pose a danger.
The issue isn't pilot lights for the oven itself; it's the stovetop. Most of the ones I've seen have individual electric lighters for each burner, which must be semi-manually activated (by turning the knob past "maximum" to a "light" setting until it catches). If you turn it to on without lighting it, or turn it off enough to put out the fire but not enough to completely cut off gas flow, you'll get a constant gas leak.
The gas safety valves I've read about aren't physical, but are actually electric. They use a thermocouple to power an electromagnet in the (sprung) safety valve.
Presumably this allows the safety valve to be located further away from the heat source reducing the risk of thermally-induced failure modes.
While it could be problematic for a stove blowing out, it's slightly worse. If in your home, the most readily available airflow is through the exhaust vent of your gas water heater or HVAC unit and either are running it's possible for the whole house fan to pull the exhaust (carbon monoxide) into the house. This is why it's very important to consider where a whole house fan is placed as well as ensuring there's enough incoming air through an open window or vent. Ours will do this if we don't open a window. For an abundance of caution, I have a CO detector in the HVAC closet as well as one's elsewhere in the house.
Our brand new, 2017 kitchen stove will happily dump unlit natural gas into the air without automatic shut-off, as far as I can tell. I've never had a burner go completely out during use, however. The highest area, lowest flow setting burner will flicker a bit when the oven heating element kicks on, but that's it.
Friend of mine bought a home and was eager to try his whole-house fan, not realizing that you need to crack open a few windows to replace the air being sucked out.
The fan worked but pulled its replacement air through the fireplace flues, covering the whole living room in soot. Not fun.
The dampers were closed, so the air pulling inside was accelerated through the cracks. That agitated the soot and made it even worse than if the dampers were open.
My parents have a whole house fan in their Atlanta, Georgia, home and its not been intentionally used in 30 years. Growing up I remember accidentally turning it on a few times and it was incredibly loud. Given the high summer heat and high humidity I don't understand why the builders included it.
I grew up in North Georgia, near Athens. My grandparents had a whole home fan like what you’re describing. Extremely loud, terrifying as a child. The house is well shaded by trees and has a full basement. The basement provides a reservoir of cool air and the fan pulls that air up from the basement into the main area of the house.
This solution wasn’t very effective in July and August. My grandmother had A/C installed not long after my grandfather died. Apparently he just refused to accept it as a necessity.
It’s interesting though. The principles have been around for a long time. I’ve been told that it’s the reason for very high ceilings in Victorian homes. The idea is that the hot air in the room rises and draws cooler air from beneath the house. In my experience, even with A/C it can be hard to stay comfortable in a house like that during the summer.
The whole-house fan was useful in swampy Waycross, GA, but we never had a house with such a fan in Athens.
Our house in Clearwater Florida, on the Gulf coast, desperately needed a whole-house exhaust fan; the compressor on the air conditioner would routinely trip a current-limiting circuit breaker, and the house would be 15 degrees F hotter than the outdoor temperatures.
Our whole-house swamp cooler in southern New Mexico worked really really well.
A friend had one in her house in NJ. They can be quiet if they are big and slow-turning.
I imagine the one in your parents house was installed before home air conditioning became commonplace. Even where they are not effective in the height of summer, they can reduce the number of days when it gets unpleasant.
They are more effective when you have a couple of thousand feet or more elevation, as the diurnal variation seems to be greater.
My home in the same area has a whole house fan, and while it doesn't get a lot of use in the summer, it's nice in the spring and the fall. Helps clear the smoke if you burn something in the kitchen as well.
I grew up in in SC in a house without AC which had a whole-house fan. It was extremely effective in the evenings after the external air temperature had fallen.
FYI, new ones aren't as loud/scary and actually move more air. Builders include it mostly in places where the outside temperatures drop significantly at night to comfortable levels before rising again during the day.
We had a house down on the Gulf of Mexico with a loud fan like that. The fan was powerful enough that it didn't just produce a constant breeze through the open windows, it produced quite a volume of wind.
The thing you have to remember was that when whole house fans were popular, the alternative wasn't to install an air conditioner, the alternative was to build a house with a screened sleeping porch so you could sleep somewhere that cooled off as quickly as the outside air did once the sun set.
In the deep south, you can still use a whole house fan reduce the number of weeks you need to run the a/c at night to sleep comfortably. Fast moving, cool, humid air blasting across your bed from an open window will have you burrowing into your blankets more quickly than you would expect.
My parents have had a whole house fan for around 10 years and love it. They can probably get through about 75% of the summer without turning on the air conditioner, leading to significant cost savings. They also have a very well insulated house, so once the cool air is inside, the house is really good at staying cool.
This would be a more valuable comment if we knew where your parents lived, approximately. The solutions for Maine are not necessarily the solutions for Minnesota or New Mexico.
I thought you need pretty dry air to cool air via evaporation. The most unbearable kind of heat is a humid one wonder how well evaporative cooling would work in tropics for that.
As the owner of a whole house fan + evaporative cooler, and someone who lives in a city where hundreds of thousands of people own and operate them, I invite Mr. Kaufman to visit Albuquerque, to watch them in everyday operation, where we've been swamping it up for over 50 years. It's a bit bizarre to read about it as if it's a brand new theory.
Let me clear up a few misconceptions:
You put the fan on the inlet next to the "pad" where the water soaks in (nowadays usually located at a central point on the roof). This works a lot better than a single outlet point for a number of reasons, not least of which the source of air can be made to have reduced dust. (Imagine a leaf blower or old diesel next to a window on a structure with negative pressure).
There are never circumstances where a whole-house fan is made less effective with humidification. It may be no more effective, but for those 100% humid nights where it's cool enough to cool down the house, the swamp still runs. In humid environments, it may warm up the house at night (due to temperatures, not humidity), which is why swamps don't get used in most places.
I'm originally from the 505, and now have an evap cooler + whole house fan in Denver. I agree that swamp coolers are very popular in Albuquerque, but I can't recall ever seeing a whole house fan down there. Are they fairly common?
If you define a whole house fan as a whole-house swamp cooler without any evaporative media or water line, then, no.
If you define a whole house fan as the part of the whole-house swamp cooler that is a huge fan and covers the whole house, whether there's water going to it or not, then, well, yes. We'll occasionally run the thing dry when the water part is on the fritz or half-shut down for the winter.
> If you define a whole house fan as the part of the whole-house swamp cooler
No - that's not what this is. A whole-house fan is a high volume extraction fan, that removes warm air from your house and expels it, usually into your attic (thus displacing hot air which also helps). Cool air is drawn in to the house through open windows, so you can control what rooms get breezes or get cooled first.
While it's interesting to know that people use swamp coolers where you live, you appear to have completely missed the point of the article.
Swamp coolers always work by displacing the indoor air with outdoor air, if they recirculated indoor air they would drive the humidity up until they were ineffective (one pass through my cooler already puts the indoor RH at 50-60%, vs. about 10% outdoors). The difference is that, in addition to replacing indoor air with outdoor air, a swamp cooler can also use evaporation to cool the outdoor air so that this is effective even when it's warmer outdoors than indoors. This does mean that you have to have windows open for a swamp cooler to function... visit a house in Albuquerque and the combination of swamp coolers and crime mean that you'll see window iron or wooden props everywhere so that air can go out without burglars coming in! The blowers in swamp coolers are powerful too, often producing a constant indoor breeze. Mine slams doors if I'm not mindful.
A normal practice for cooling is to run the blower when outdoor temps are lower than indoor, and then both the blower and pump when outdoor temps are higher. Thermostats are available but not very common on swamp coolers, one reason is that independent control of the pump and blower makes them a bit more complicated than an "on/off" behavior, and another is that they take time to displace the indoor air so they work best if you anticipate the daily trends by cooling the house farther than target before temps really climb in the late morning. During weather like we have in Albuquerque right now, lows in the '70s and highs in the '90s, you will run the blower 24/7 but might stop the pump when the house gets cool enough.
I've thought about it a bit and I can't really see how what's described in the article is different from the normal "best practice" for swamp coolers - bringing in outside air, with or without additional evaporative cooling depending on the outside temperature. He refers to the advantages of closing up the house to retain the cool air, but if that's sufficient (and it is for a while in spring and fall) you just turn off the swamp cooler and close the windows during the day, no extra hardware is needed.
Author here: I don't know very much about how swamp coolers are used in practice, so I could easily be missing something. I do know that they're basically never used up here in the Northeast (Boston) because they work by increasing humidity and in the summer we tend to have pretty high humidity already. We also tend to have daytime highs high enough that the air leaving a swamp cooler would be warmer than the temperature of a structure that's been cooled overnight with a whole-house fan, plus more humid, which means during the hotter parts of the day you don't want to bring in outside air. So, how could a swamp cooler be used without increasing the daytime humidity of the house?
What I'm imagining is running a swamp cooler overnight to cool the structure of the house as close to the wet bulb temperature as possible, then in the early morning run it a bit in fan-only mode to bring in drier outside air (accepting that this will warm the house up a bit), and then shut the house up and turn the cooler off for the day.
What we currently do is run a whole-house fan overnight, and shut the house up during the day, with no swamp cooler. I'm trying to figure out whether adding some evaporation to the system could make sense.
Evaporative cooling is not worth doing in Boston for the space in a residence. It can be used, however, to improve the efficiency of refrigerated air units. Take a look at air conditioner misters that spray hose water onto the radiators for refrigerated air units. Although I suspect a good percentage of that heat is carried away simply by conduction rather than evaporation, it could conceivably cut your air conditioner bills. Water-cooled whole-house air conditioners are high maintenance, otherwise they'd be commonplace.
The other approaches involve tag-teaming a refrigerated air unit with a swamp cooler. The air intake for a refrigerated air system would work a lot better at 80 degrees, 80% humidity than 90 degrees, 60% humidity. I am told this is commonplace in Phoenix.
One other often-overlooked characteristic of the "swamp cooler zone" is that it tends to be at high altitudes, which aside from keeping things dry and cool enough to have a shot at good-enough cooling, requires doubling the size of refrigerated air units to keep pace with design specs. The air is thinner enough up here that the radiator can't keep up as well. This shifts the balance slightly in the direction of swamp. This has been what feels like an unusually hot and humid summer in Albuquerque, and our household finally sprung for a room air conditioner, run in parallel with the swamp.
You should look into building elements with micro encapsulated phase change materials. They're becoming popular nowadays, and you can find ceiling panels and wall panels from commericals suppliers. The pcm melts during the day cooling down the room, you recharge it at night by using a whole house fan to continuously pass cool air throughout the house.
> There are never circumstances where a whole-house fan is made less effective with humidification. It may be no more effective, but for those 100% humid nights where it's cool enough to cool down the house, the swamp still runs.
This. Put simply, the wet bulb temperature is always colder than the dry bulb temperature.
There is a somewhat new company out of India which has an improved approach. As others mentioned, swamp coolers have been around for a long time, especially in India. They are not popular anymore but AC's are expensive.
Their approach is use the refrigerative compressor to chill water for an cooler instead of chilling the air.
The efficiency is greatly improved and they claim 10% of running costs.
Yes I edited my comment. Looks like the approach of vaayu is to directly do evaporative cooling. So a chilled water swamp cooler. The commercial systems use the chilled water in closed coils.
My condo has a whole house fan, which is rigged up to a wireless remote that the former owner couldn't find. I need to spend twenty minutes setting up a new remote wiring setup, but it's only punishingly hot 2-3 days a year in Oakland, and on those 2-3 days, I know that even if I prime it, the heat will be over by the time the remote arrives, so I never pull the trigger.
Tldr, this is why we need same day voter registration.
As the cofounder of a heavily HVAC-related tech company, I can echo that this is indeed nowhere near a new idea.
Many large commercial buildings already do something similar, but instead of blowing cool, humid air through the structure, they use evaporation to cool the water itself in a condenser loop (with large cooling towers moving outside air across the water as it cascades down within the towers). The condenser water then enters a heat exchanger where it cools another loop of water that flows to the cooling coils in blower units throughout the building (you don't want dirty water that's been in contact with outside air going through cooling coils, so they are isolated loops).
Bear in mind, as others have mentioned, this approach is humidity-limited and is therefore rarely seen outside of arid regions. And also note that humidity levels tend to be highest at night when the air is the coolest, which further limits the effectiveness of evaporative cooling at night. Once relative humidity reaches 100%, you get absolutely no cooling from evaporation.
My concert with swamp coolers is the increase of humidity along with warm temperatures. Creates a breeding ground for mold growth. The idea is great but application depends on your structure.
My family lived in Phoenix, AZ since i was 6, and he had an Evap Cool and a traditional AC. Early in the summer the Evap works great and is way cheaper. Once it gets too hot or too humid, you switch over to the AC. The fun part was, my Dad would hold off switching as long as he could, and kind of compete with a friend nearby to see who could "stand it with the evap" as long as possible.
The hardest part i couldn't ever keep straight, was with the Evap you need doors open and with the AC you close them. i would get it straight by the time he'd switch over to the other system..
> Another option would be to use the wall, ceiling, or floor as an evaporative surface.
This proposal may seem over-complicated at first, but low-tech cob walls naturally exploit this effect by "breathing" humidity.
"these results show that earth buildings in diverse climates have significant potential to cool themselves evaporatively through sorption of moisture from humid night air and evaporation during the following day’s heat."
Evaporative cooler owner here. Thought I would add a few data points in case people were curious. We live in Denver, CO (arid climate, typically mid 90Fs in the summer but can reach over 100F. We tied the all time record of 105 in June FYI).
We inherited a MasterCool evaporative cooler (think big metal box where the evaporative pads are made of aspen fibers) when we bought our house. It wasn't very well sealed so we were only able to drive the temperature down ~10-15 degrees F so it would get pretty uncomfortable once it got above 90.
Replaced recently with a Breezair unit and it's been way better. The air it draws in seems to all be going through the evaporation media so we've been able to maintain 72-75 degrees in our old drafty house throughout the summer so far. I mostly don't mind the added humidity as I get fairly dry skin but we have a few doors which swell and stick due to absorbing the additional moisture.
I really wanted to get a Coolerado unit but they only seem to be readily available for commercial applications. The difference with this unit is that it is an indirect evaporative cooler so the air it blows into the cooled space has no added humidity (and it claims to be able to achieve > 100% wet bulb temperature due to its design [1]).
A home built in the 1860s uses the principle of the whole house fan, but without the fan: you just open the windows at night and close 'em during the day, and you can regulate more with an attic trap door. It works well most of the time, but sometimes there's problems.
Namely, if humidity gets trapped in the house, when you shut the house during the day, it can smell like mildew. It can be near-impossible to remove the humidity from the house without an air conditioner of some sort, or a dehumidifier. An evaporative cooler at night would make this worse because you're adding humidity.
Another problem is multiple storeys. The top floor will always be hotter, and it can build during hot days and leech the cool air from below. You need a powerful attic fan to remove excess heat and humidity or the top floor will become a swamp.
If you live in a big city, the average ambient temperature during the summer is probably going to be high enough that a whole house fan will not replace air conditioning, but could supplement it.
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[ 3.2 ms ] story [ 174 ms ] threadNot as good as placing one in the attic, but a really effective alternative that can be carried from property to property.
Whole house fans do help a lot in pulling cooler outside air into the inhabited spaces.
It should have the same net effect as far as I can see. I'm curious why systems don't have an option to do this.
In my part of the country it cools off at night, but the wind typically stalls. At least drawing in some of that air could let me skip running the A/C compressor overnight.
I just added a whole house fan to my home in the bay area and it works very well - the temperature drops by as much as 30+ degrees from daytime to night time here.
I really appreciate the simplicity of not having AC infrastructure anywhere in my house.
However, I have lived in other climates, like Minnesota, where the nighttime temperature does not drop much at all and I am not sure it would be worth the effort. If it was a box to tick for new construction, then sure - but I wouldn't go out of my way to add it to a house after the fact ...
https://en.wikipedia.org/wiki/Windcatcher
https://en.wikipedia.org/wiki/Qanat
http://www.lessoireesdeparis.com/wp-content/uploads/2016/02/...
Big respect to the builders/engineers. It's 2400 years old
https://twitter.com/wrathofgnon/status/1019056740128600065
- https://en.wikipedia.org/wiki/Ground-coupled_heat_exchanger
- https://en.wikipedia.org/wiki/Trombe_wall
If the roof insulation is less than perfect, simply wetting the roof periodically will go a long way toward drawing heat out of the house.
If the roof insulation is good enough that this wouldn't work, you very likely don't have a problem to begin with.
Aside: that LTM article made me think of a complaint of a friend of mine on that the solar panels on his house are almost never at optimal efficiency due to temperature. At which point I asked him if active cooling of solar panels using heat transport + a heat buffer underneath the house + re-using said heat in winter might be a win-win solution for that - he thought it was a good idea but also too ambitious a project for him to undertake.
Shared all HN links with the author, hope he joins in on the discussion here.
[0] "Ditch the Batteries: Off-Grid Compressed Air Energy Storage", http://www.lowtechmagazine.com/2018/05/ditch-the-batteries-o...
[1] https://news.ycombinator.com/item?id=17143163
I also don't trust government bureaucrats to figure this all out, either.
A carbon tax basically would just reward good ideas in the market, and punish the bad ones.
However, almost no one supports it. You get some big figures like Musk and the economist, Mankiw; but both the left and the right of mainstream politics don't want it. The right doesn't want new taxes nor to particularly combat global warming; the left is ideologically opposed to market-based solutions and instead supports big government/power-grab solutions--specifically cap and trade.
TL;DR consider supporting a carbon tax if you like these ideas and want to combat global warming
Lots of left-wing ideologies favour using market mechanisms this way, and I wish more would - you can want to use market-mechanisms this way whether or not you're for free-market competition in terms of valuation and trade of company shares.
In reality, the two "choices" imposed upon us are Coke and Pepsi, two noxious compounds that require extended chemical analysis to differentiate. They both want more war, all the time, in every case, for whatever reason. The real reason, of course, is so that they may skim some of those sweet armaments manufacturing profits. No it's not a conspiracy. Important influencers know which side of their toast is buttered, but they are a small minority and they don't need to coordinate in secret. Everyone who doesn't revolve from bureaucratic post to public office to lobbyist to executive board to think-tank sinecure, is a mere useful idiot. If 10-20% of American voters ever learn about horseshoe theory, they'll be screwed. Therefore the media mentions that about as often as they mention e.g. Libya or Yemen.
So, it's little surprise that we Americans have no clue about leftist thought.
Nothing was conflated.
Carbon taxes have a substantial base of support on the left (possibly more than cap and trade, whose base of support is more centrist.)
Now, carbon-tax supporters are likely to support cap-and-trade as better than nothing, but that's different than preferring it and opposing carbon taxes.
Yes, this idea has occured to other people. They are called PVT Solar Panels (PVT=Photovoltaic + Thermal).
https://green.blogs.nytimes.com//2008/09/29/waste-not-want-n...
If you want data, go to your local gas supplier and talk to the technicians who maintain the high-pressure compressors. It's not rocket surgery but still way beyond the abilities of most homeowners.
Sure, the article is not peer reviewed. Neither is your comment. Dismissing the citations as mostly not peer reviewed is just disingenuous; the majority of them are from journals on energy, conferences on applied energy, and other relevant fields of research.
Using "the local gas supplier and the technicians maintaining high-pressure compressors" as an counter-argument is just as flawed, unless you're seriously claiming that they are more likely to be a source of peer reviewed knowledge about the latest developments in compressible energy storage than the work of the cited researchers.
Look, I'm not saying that this is ready for usage; the article itself ends with:
> In conclusion, small-scale compressed air energy storage could be a promising alternative to batteries, but the research is still in its early stages – the first study on small-scale CAES was published in 2010 – and new ideas will continue to shed light on how best to develop the technology. At the moment, there are no commercial products available, and setting up your own system can be quite intimidating if you are new to pneumatics. Simply getting hold of the right components and fittings is a headache, as these come in a bewildering variety and are only sold to industries.
But you're being dismissive of a technology in quick development without even engaging with the article.
It has only happened to me once or twice, and is a non issue if you choose which window(s) to open carefully.
That being said, we love our total home fan, and it's also great for clearing out various odors
Edit: if people are having campfires near your house you'll want to shut it off asap
I know of no gas stove that has such a feature, though.
For kitchen stoves, most have electronic ignition as well. For an older stove, the amount of gas released from an unlit pilot is not significant enough to pose a danger.
The exception being camping stoves which I think may not have had it.
Presumably this allows the safety valve to be located further away from the heat source reducing the risk of thermally-induced failure modes.
The fan worked but pulled its replacement air through the fireplace flues, covering the whole living room in soot. Not fun.
This solution wasn’t very effective in July and August. My grandmother had A/C installed not long after my grandfather died. Apparently he just refused to accept it as a necessity.
It’s interesting though. The principles have been around for a long time. I’ve been told that it’s the reason for very high ceilings in Victorian homes. The idea is that the hot air in the room rises and draws cooler air from beneath the house. In my experience, even with A/C it can be hard to stay comfortable in a house like that during the summer.
Our house in Clearwater Florida, on the Gulf coast, desperately needed a whole-house exhaust fan; the compressor on the air conditioner would routinely trip a current-limiting circuit breaker, and the house would be 15 degrees F hotter than the outdoor temperatures.
Our whole-house swamp cooler in southern New Mexico worked really really well.
I imagine the one in your parents house was installed before home air conditioning became commonplace. Even where they are not effective in the height of summer, they can reduce the number of days when it gets unpleasant.
They are more effective when you have a couple of thousand feet or more elevation, as the diurnal variation seems to be greater.
The thing you have to remember was that when whole house fans were popular, the alternative wasn't to install an air conditioner, the alternative was to build a house with a screened sleeping porch so you could sleep somewhere that cooled off as quickly as the outside air did once the sun set.
https://en.wikipedia.org/wiki/Sleeping_porch
In the deep south, you can still use a whole house fan reduce the number of weeks you need to run the a/c at night to sleep comfortably. Fast moving, cool, humid air blasting across your bed from an open window will have you burrowing into your blankets more quickly than you would expect.
48 degrees dry heat is pretty unbearable.[1] Bagdad can get hot too, hot and dry, 51.1 record high.[2]
1. https://en.wikipedia.org/wiki/Port_Augusta#Climate
2. https://en.wikipedia.org/wiki/Baghdad#Climate
Let me clear up a few misconceptions: You put the fan on the inlet next to the "pad" where the water soaks in (nowadays usually located at a central point on the roof). This works a lot better than a single outlet point for a number of reasons, not least of which the source of air can be made to have reduced dust. (Imagine a leaf blower or old diesel next to a window on a structure with negative pressure).
There are never circumstances where a whole-house fan is made less effective with humidification. It may be no more effective, but for those 100% humid nights where it's cool enough to cool down the house, the swamp still runs. In humid environments, it may warm up the house at night (due to temperatures, not humidity), which is why swamps don't get used in most places.
If you define a whole house fan as the part of the whole-house swamp cooler that is a huge fan and covers the whole house, whether there's water going to it or not, then, well, yes. We'll occasionally run the thing dry when the water part is on the fritz or half-shut down for the winter.
No - that's not what this is. A whole-house fan is a high volume extraction fan, that removes warm air from your house and expels it, usually into your attic (thus displacing hot air which also helps). Cool air is drawn in to the house through open windows, so you can control what rooms get breezes or get cooled first.
While it's interesting to know that people use swamp coolers where you live, you appear to have completely missed the point of the article.
A normal practice for cooling is to run the blower when outdoor temps are lower than indoor, and then both the blower and pump when outdoor temps are higher. Thermostats are available but not very common on swamp coolers, one reason is that independent control of the pump and blower makes them a bit more complicated than an "on/off" behavior, and another is that they take time to displace the indoor air so they work best if you anticipate the daily trends by cooling the house farther than target before temps really climb in the late morning. During weather like we have in Albuquerque right now, lows in the '70s and highs in the '90s, you will run the blower 24/7 but might stop the pump when the house gets cool enough.
I've thought about it a bit and I can't really see how what's described in the article is different from the normal "best practice" for swamp coolers - bringing in outside air, with or without additional evaporative cooling depending on the outside temperature. He refers to the advantages of closing up the house to retain the cool air, but if that's sufficient (and it is for a while in spring and fall) you just turn off the swamp cooler and close the windows during the day, no extra hardware is needed.
What I'm imagining is running a swamp cooler overnight to cool the structure of the house as close to the wet bulb temperature as possible, then in the early morning run it a bit in fan-only mode to bring in drier outside air (accepting that this will warm the house up a bit), and then shut the house up and turn the cooler off for the day.
What we currently do is run a whole-house fan overnight, and shut the house up during the day, with no swamp cooler. I'm trying to figure out whether adding some evaporation to the system could make sense.
Evaporative cooling is not worth doing in Boston for the space in a residence. It can be used, however, to improve the efficiency of refrigerated air units. Take a look at air conditioner misters that spray hose water onto the radiators for refrigerated air units. Although I suspect a good percentage of that heat is carried away simply by conduction rather than evaporation, it could conceivably cut your air conditioner bills. Water-cooled whole-house air conditioners are high maintenance, otherwise they'd be commonplace.
The other approaches involve tag-teaming a refrigerated air unit with a swamp cooler. The air intake for a refrigerated air system would work a lot better at 80 degrees, 80% humidity than 90 degrees, 60% humidity. I am told this is commonplace in Phoenix.
One other often-overlooked characteristic of the "swamp cooler zone" is that it tends to be at high altitudes, which aside from keeping things dry and cool enough to have a shot at good-enough cooling, requires doubling the size of refrigerated air units to keep pace with design specs. The air is thinner enough up here that the radiator can't keep up as well. This shifts the balance slightly in the direction of swamp. This has been what feels like an unusually hot and humid summer in Albuquerque, and our household finally sprung for a room air conditioner, run in parallel with the swamp.
This. Put simply, the wet bulb temperature is always colder than the dry bulb temperature.
https://en.wikipedia.org/wiki/Wet-bulb_temperature
Their approach is use the refrigerative compressor to chill water for an cooler instead of chilling the air.
The efficiency is greatly improved and they claim 10% of running costs.
https://www.thebetterindia.com/52984/vaayu-hybrid-chillers-c...
http://www.vaayuindia.com/
http://www.york.com/for-your-workplace/chilled-water-systems
Tldr, this is why we need same day voter registration.
Many large commercial buildings already do something similar, but instead of blowing cool, humid air through the structure, they use evaporation to cool the water itself in a condenser loop (with large cooling towers moving outside air across the water as it cascades down within the towers). The condenser water then enters a heat exchanger where it cools another loop of water that flows to the cooling coils in blower units throughout the building (you don't want dirty water that's been in contact with outside air going through cooling coils, so they are isolated loops).
Bear in mind, as others have mentioned, this approach is humidity-limited and is therefore rarely seen outside of arid regions. And also note that humidity levels tend to be highest at night when the air is the coolest, which further limits the effectiveness of evaporative cooling at night. Once relative humidity reaches 100%, you get absolutely no cooling from evaporation.
The hardest part i couldn't ever keep straight, was with the Evap you need doors open and with the AC you close them. i would get it straight by the time he'd switch over to the other system..
This proposal may seem over-complicated at first, but low-tech cob walls naturally exploit this effect by "breathing" humidity.
"these results show that earth buildings in diverse climates have significant potential to cool themselves evaporatively through sorption of moisture from humid night air and evaporation during the following day’s heat."
~~ Intrinsic Evaporative Cooling by Hygroscopic Earth Materials, http://www.mdpi.com/2076-3263/6/3/38/htm
We inherited a MasterCool evaporative cooler (think big metal box where the evaporative pads are made of aspen fibers) when we bought our house. It wasn't very well sealed so we were only able to drive the temperature down ~10-15 degrees F so it would get pretty uncomfortable once it got above 90.
Replaced recently with a Breezair unit and it's been way better. The air it draws in seems to all be going through the evaporation media so we've been able to maintain 72-75 degrees in our old drafty house throughout the summer so far. I mostly don't mind the added humidity as I get fairly dry skin but we have a few doors which swell and stick due to absorbing the additional moisture.
I really wanted to get a Coolerado unit but they only seem to be readily available for commercial applications. The difference with this unit is that it is an indirect evaporative cooler so the air it blows into the cooled space has no added humidity (and it claims to be able to achieve > 100% wet bulb temperature due to its design [1]).
[1] http://www.coolerado.com/pdfs/PowerMagMCTCfiguresCooleradoTI...
What are the costs and specs on such equipment?
Cost on the other hand doesn't seem to be readily available (my guess is expensive since they seem to be targeting businesses vs consumers).
[1] http://www.coolerado.com/m50-energy-efficient-air-conditione... (Downloads tab)
Namely, if humidity gets trapped in the house, when you shut the house during the day, it can smell like mildew. It can be near-impossible to remove the humidity from the house without an air conditioner of some sort, or a dehumidifier. An evaporative cooler at night would make this worse because you're adding humidity.
Another problem is multiple storeys. The top floor will always be hotter, and it can build during hot days and leech the cool air from below. You need a powerful attic fan to remove excess heat and humidity or the top floor will become a swamp.
If you live in a big city, the average ambient temperature during the summer is probably going to be high enough that a whole house fan will not replace air conditioning, but could supplement it.