Whole House Fan and Evaporative Cooler
jefftk.com
jefftk.com
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.
http://www.lessoireesdeparis.com/wp-content/uploads/2016/02/...
Big respect to the builders/engineers. It's 2400 years old
- https://en.wikipedia.org/wiki/Ground-coupled_heat_exchanger
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...
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.
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.
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)
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..
Not 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 ...
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 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
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.
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.york.com/for-your-workplace/chilled-water-systems
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.
48 degrees dry heat is pretty unbearable.[1] Bagdad can get hot too, hot and dry, 51.1 record high.[2]
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.
Tldr, this is why we need same day voter registration.