12 ms·

Whole House Fan and Evaporative Cooler

148 points by luu 8y ago

weaksauce 8y ago
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.
- germinalphrase 8y ago
  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.
- athorax 8y ago
  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.
  - blacksmith_tb 8y ago
    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).
    - JoblessWonder 8y ago
      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.
  - secabeen 8y ago
    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.
- joezydeco 8y ago
  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.
  - djrogers 8y ago
    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...
    - joezydeco 8y ago
      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.
      - djrogers 8y ago
        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.
- patcheudor 8y ago
  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.
- rsync 8y ago
  "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 ...
Sharlin 8y ago
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. https://en.wikipedia.org/wiki/Windcatcher https://en.wikipedia.org/wiki/Windcatcher https://en.wikipedia.org/wiki/Qanat https://en.wikipedia.org/wiki/Qanat
- agumonkey 8y ago
  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. http://www.lessoireesdeparis.com/wp-content/uploads/2016/02/Les-poutres-gondole-de-E.-Albert-le-dallade-de-J.-Lagrange-et-le-mur-miroir-dArchitecture-studio.jpg http://www.lessoireesdeparis.com/wp-content/uploads/2016/02/...
- saiya-jin 8y ago
  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
  - matt4077 8y ago
    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.
    - gabriel34 8y ago
      He was banned and notified of it: https://news.ycombinator.com/item?id=13606809 https://news.ycombinator.com/item?id=13606809
  - miscreanity 8y ago
    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.
samatman 8y ago
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.
- killjoywashere 8y ago
  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.
  - ams6110 8y ago
    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.
- ilikehurdles 8y ago
  With evaporative coolers, it’s common to leave some window(s) open while running it. Those serve as the exhaust for the warm air.
vanderZwan 8y ago
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. [0] "Ditch the Batteries: Off-Grid Compressed Air Energy Storage", http://www.lowtechmagazine.com/2018/05/ditch-the-batteries-off-the-grid-compressed-air-energy-storage.html http://www.lowtechmagazine.com/2018/05/ditch-the-batteries-o... [1] https://news.ycombinator.com/item?id=17143163 https://news.ycombinator.com/item?id=17143163
- wallace_f 8y ago
  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
  - vidarh 8y ago
    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.
skate22 8y ago
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
- MrBuddyCasino 8y ago
  Isn't there a temperature sensor that will shut down gas supply if heat stops?
  - azernik 8y ago
    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.
    - ams6110 8y ago
      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.
      - azernik 8y ago
        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.
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rietta 8y ago
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.
- powvans 8y ago
  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.
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  - watersb 8y ago
    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.
- mannykannot 8y ago
  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.
froindt 8y ago
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.
- dsr_ 8y ago
  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.
  - froindt 8y ago
    Late on the reply, but Iowa.
perlpimp 8y ago
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.
- loourr 8y ago
  you do, this would only work in arid climates.
- TheSpiceIsLife 8y ago
  Six of one, half a dozen of the other. 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 https://en.wikipedia.org/wiki/Port_Augusta#Climate 2. https://en.wikipedia.org/wiki/Baghdad#Climate https://en.wikipedia.org/wiki/Baghdad#Climate
mchannon 8y ago
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.
- athorax 8y ago
  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?
  - mchannon 8y ago
    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.
    - djrogers 8y ago
      > 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.
anotheramala 8y ago
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. https://www.thebetterindia.com/52984/vaayu-hybrid-chillers-cooler-air-conditioner-indore/ https://www.thebetterindia.com/52984/vaayu-hybrid-chillers-c... http://www.vaayuindia.com/ http://www.vaayuindia.com/
- brudgers 8y ago
  Large buildings commonly use chilled water HVAC systems. The scale at which these systems make sense is larger than a single family residence. http://www.york.com/for-your-workplace/chilled-water-systems http://www.york.com/for-your-workplace/chilled-water-systems
  - anotheramala 8y ago
    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.
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fakename 8y ago
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.
naushniki 8y ago
https://www.youtube.com/watch?v=Mo3psiMZjGc https://www.youtube.com/watch?v=Mo3psiMZjGc
bsmith 8y ago
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.
- gm-conspiracy 8y ago
  The domain in your profile is not currently active.
  - bsmith 8y ago
    Yikes! Thanks...I need to fix that.
- pkaye 8y ago
  Will it work in the bay area on a hot day? What kind of humidity levels are acceptable?
- cryptonector 8y ago
  Would it work in central Texas? It's not as dry as AZ, but it's bone-dry by comparison to the swamp known as Houston.
martin1b 8y ago
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.
dlhavema 8y ago
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..
schiffern 8y ago
> 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." ~~ Intrinsic Evaporative Cooling by Hygroscopic Earth Materials, http://www.mdpi.com/2076-3263/6/3/38/htm http://www.mdpi.com/2076-3263/6/3/38/htm
cjenkins 8y ago
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]). [1] http://www.coolerado.com/pdfs/PowerMagMCTCfiguresCooleradoTIC.pdf http://www.coolerado.com/pdfs/PowerMagMCTCfiguresCooleradoTI...
- gm-conspiracy 8y ago
  The Coolerado looks like a self-contained evaporative cooler with a heat-exchanger. What are the costs and specs on such equipment?
  - cjenkins 8y ago
    The specs seem fairly detailed (at least to a non-HVAC person) on their website [IE: 1]. 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-conditioner/ http://www.coolerado.com/m50-energy-efficient-air-conditione... (Downloads tab)
peterwwillis 8y ago
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.

148 points by luu 8y ago

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.

germinalphrase 8y ago
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.
athorax 8y ago
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.
- blacksmith_tb 8y ago
  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).
  - JoblessWonder 8y ago
    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.
- secabeen 8y ago
  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.
joezydeco 8y ago
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.
- djrogers 8y ago
  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...
  - joezydeco 8y ago
    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.
    - djrogers 8y ago
      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.
patcheudor 8y ago
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.
rsync 8y ago
"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 ...

Sharlin 8y ago

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. https://en.wikipedia.org/wiki/Windcatcher https://en.wikipedia.org/wiki/Windcatcher https://en.wikipedia.org/wiki/Qanat https://en.wikipedia.org/wiki/Qanat

agumonkey 8y ago
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. http://www.lessoireesdeparis.com/wp-content/uploads/2016/02/Les-poutres-gondole-de-E.-Albert-le-dallade-de-J.-Lagrange-et-le-mur-miroir-dArchitecture-studio.jpg http://www.lessoireesdeparis.com/wp-content/uploads/2016/02/...
saiya-jin 8y ago
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
- matt4077 8y ago
  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.
  - gabriel34 8y ago
    He was banned and notified of it: https://news.ycombinator.com/item?id=13606809 https://news.ycombinator.com/item?id=13606809
- miscreanity 8y ago
  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.

samatman 8y ago

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.

killjoywashere 8y ago
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.
- ams6110 8y ago
  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.
ilikehurdles 8y ago
With evaporative coolers, it’s common to leave some window(s) open while running it. Those serve as the exhaust for the warm air.

vanderZwan 8y ago

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. [0] "Ditch the Batteries: Off-Grid Compressed Air Energy Storage", http://www.lowtechmagazine.com/2018/05/ditch-the-batteries-off-the-grid-compressed-air-energy-storage.html http://www.lowtechmagazine.com/2018/05/ditch-the-batteries-o... [1] https://news.ycombinator.com/item?id=17143163 https://news.ycombinator.com/item?id=17143163

wallace_f 8y ago
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
- vidarh 8y ago
  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.

skate22 8y ago

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

MrBuddyCasino 8y ago
Isn't there a temperature sensor that will shut down gas supply if heat stops?
- azernik 8y ago
  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.
  - ams6110 8y ago
    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.
    - azernik 8y ago
      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.

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rietta 8y ago

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.

powvans 8y ago
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.
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- watersb 8y ago
  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.
mannykannot 8y ago
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.

froindt 8y ago

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.

dsr_ 8y ago
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.
- froindt 8y ago
  Late on the reply, but Iowa.

perlpimp 8y ago

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.

loourr 8y ago
you do, this would only work in arid climates.
TheSpiceIsLife 8y ago
Six of one, half a dozen of the other. 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 https://en.wikipedia.org/wiki/Port_Augusta#Climate 2. https://en.wikipedia.org/wiki/Baghdad#Climate https://en.wikipedia.org/wiki/Baghdad#Climate

mchannon 8y ago

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.

athorax 8y ago
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?
- mchannon 8y ago
  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.
  - djrogers 8y ago
    > 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.

anotheramala 8y ago

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. https://www.thebetterindia.com/52984/vaayu-hybrid-chillers-cooler-air-conditioner-indore/ https://www.thebetterindia.com/52984/vaayu-hybrid-chillers-c... http://www.vaayuindia.com/ http://www.vaayuindia.com/

brudgers 8y ago
Large buildings commonly use chilled water HVAC systems. The scale at which these systems make sense is larger than a single family residence. http://www.york.com/for-your-workplace/chilled-water-systems http://www.york.com/for-your-workplace/chilled-water-systems
- anotheramala 8y ago
  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.
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fakename 8y ago

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.

naushniki 8y ago

https://www.youtube.com/watch?v=Mo3psiMZjGc https://www.youtube.com/watch?v=Mo3psiMZjGc

bsmith 8y ago

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.

gm-conspiracy 8y ago
The domain in your profile is not currently active.
- bsmith 8y ago
  Yikes! Thanks...I need to fix that.
pkaye 8y ago
Will it work in the bay area on a hot day? What kind of humidity levels are acceptable?
cryptonector 8y ago
Would it work in central Texas? It's not as dry as AZ, but it's bone-dry by comparison to the swamp known as Houston.

martin1b 8y ago

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.

dlhavema 8y ago

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..

schiffern 8y ago

> 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." ~~ Intrinsic Evaporative Cooling by Hygroscopic Earth Materials, http://www.mdpi.com/2076-3263/6/3/38/htm http://www.mdpi.com/2076-3263/6/3/38/htm

cjenkins 8y ago

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]). [1] http://www.coolerado.com/pdfs/PowerMagMCTCfiguresCooleradoTIC.pdf http://www.coolerado.com/pdfs/PowerMagMCTCfiguresCooleradoTI...

gm-conspiracy 8y ago
The Coolerado looks like a self-contained evaporative cooler with a heat-exchanger. What are the costs and specs on such equipment?
- cjenkins 8y ago
  The specs seem fairly detailed (at least to a non-HVAC person) on their website [IE: 1]. 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-conditioner/ http://www.coolerado.com/m50-energy-efficient-air-conditione... (Downloads tab)

peterwwillis 8y ago

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.