DaveinOlyWA
Posts: 13144
Joined: Sat Apr 24, 2010 7:43 pm
Delivery Date: 16 Feb 2018
Leaf Number: 314199
Location: Olympia, WA
Contact: Website

Re: "The Cost of Cool". Air conditioning has changed the wor

Wed Oct 24, 2012 1:23 pm

like any energy usage, A/C's #1 way of reducing its power usage is not increases in efficiency, its building design and conservation.

cant tell you how many times I have experienced A/C that was way too cold. now, i prefer it to be cooler and frequently am comfortable when SO is wearing a sweater and still complaining so for me to be cold is something not easily accomplished
2011 SL; 44,598 miles. 2013 S; 44,840 miles.2016 S30 deceased. 29,413 miles. 2018 S40; 8743 miles, 485 GIDs, 37.6 kwh 111.39 Ahr , SOH 96.49, Hx 114.98
My Blog; http://daveinolywa.blogspot.com" onclick="window.open(this.href);return false;

AndyH
Posts: 6384
Joined: Fri Apr 23, 2010 3:43 pm
Location: San Antonio

Re: "The Cost of Cool". Air conditioning has changed the wor

Wed Oct 24, 2012 1:55 pm

Smidge204 wrote:
AndyH wrote:We have solutions that go back many years yet are still in use on the planet. No electricity necessary, but one does need falling water.

I really have to question the overall efficiency of such a system. Granted, the energy is "free" in that you are presumably using existing flowing water, but I can't help but think you'd be better off converting the water's flow to mechanical energy to drive a more conventional refrigeration cycle machine - no need for the electrical conversion.

It's a quaint idea and certainly simple in concept and implementation, which has its advantages. Again, though, my gut feeling is you can get more bang for your buck(et) using more modern technologies.
=Smidge=

Efficiency? It's like talking about solar panel efficiency, or 'complaining' that trees are only about 1% efficient. Why do we care if it's free and there's many thousands of times more capacity available than need?

I understand that we love our tech. But it's not always the best solution, or the most appropriate solution.

Another case in point - look at passive solar design. It's amazingly simple to keep sun out of buildings in the summer when we want it cool, yet let more sun inside in the winter - and we don't need computerized blinds with battery backup. This tech is many thousands of years old and still in use today.

It's very easy to pull air from underground where it's cool and dehumidified and pull it through buildings using a solar chimney. Again - no computers, no electricity - and it automatically works during the day when we need the cooling. It worked in ancient Rome and is working in homes around the world today.

Add compressed air to the cooling tube and now we've got free air conditioning - a free stream of dehumidified cold air that is moved thru the building with no fans. Sure, we could put a temperature controlled valve on the air supply and interface it to a TCP/IP stream so we can monitor it on an iPhone if we want. :lol:

The oil age allowed us to get very sloppy with energy similar to the way larger microprocessors allowed programmers to freely develop bloatware. But just because we CAN create an application that uses 72.6 quintillion lines of code doesn't mean we HAVE to - and certainly doesn't mean it's the best way to solve the problem.
"The stupid become extinct."-Bill Mollison
2018 Outlander PHEV
2015 smart Electric Drive (lease ended Feb, 2018)
OpenEVSE Plus DIY

Smidge204
Posts: 940
Joined: Wed Nov 24, 2010 1:42 pm

Re: "The Cost of Cool". Air conditioning has changed the wor

Wed Oct 24, 2012 2:23 pm

AndyH wrote:Efficiency? It's like talking about solar panel efficiency, or 'complaining' that trees are only about 1% efficient. Why do we care if it's free and there's many thousands of times more capacity available than need?
I'm not completely convinced we have enough tappable cooling capacity in free-running water but whatever. Even if we do, efficiency matters because unlike solar panels not everyone has a decent sized stream in their back yard. Those fortunate enough to have such resources may not have enough to meet their cooling needs.

(And efficiency of solar does matter, since the total surface area you need to meet a given power demand is inversely proportional efficiency. More efficient panels means you need less real-estate and consequently lower costs.)


AndyH wrote:It's very easy to pull air from underground where it's cool and dehumidified and pull it through buildings using a solar chimney. Again - no computers, no electricity - and it automatically works during the day when we need the cooling. It worked in ancient Rome and is working in homes around the world today.
It would be very difficult to pull air from underground around here, considering in some locations the water table is so high the earth practically squirts you in the eye like an overripe grapefruit if you dig your toe in. :lol:

I'd also contend that air that has been cooled with direct contact with water is anything but "dehumidified." It will be at the saturation point. You will have damp, cool air. Gotta warm it up a bit first in the absence of water. Mixing in some fresh outdoor air is a good way to do this providing it's not humid out.

Edit: For what it's worth, geothermal heat pumps are becoming quite popular around here and would likely be more so if our electricity wasn't so expensive. Geothermal + Solar anyone?


AndyH wrote:The oil age allowed us to get very sloppy with energy similar to the way larger microprocessors allowed programmers to freely develop bloatware. But just because we CAN create an application that uses 72.6 quintillion lines of code doesn't mean we HAVE to - and certainly doesn't mean it's the best way to solve the problem.

I agree! But the oil age has also allowed human civilization to spread and flourish in places we previously could not. Bringing an end to the oil age means either finding suitable ways to replace oil, or abandoning much of our civilization. No points for guessing which option I'm in favor of ;)
=Smidge=

DaveinOlyWA
Posts: 13144
Joined: Sat Apr 24, 2010 7:43 pm
Delivery Date: 16 Feb 2018
Leaf Number: 314199
Location: Olympia, WA
Contact: Website

Re: "The Cost of Cool". Air conditioning has changed the wor

Wed Oct 24, 2012 2:57 pm

Very valid points and oil is the reason why places like Phoenix exists
2011 SL; 44,598 miles. 2013 S; 44,840 miles.2016 S30 deceased. 29,413 miles. 2018 S40; 8743 miles, 485 GIDs, 37.6 kwh 111.39 Ahr , SOH 96.49, Hx 114.98
My Blog; http://daveinolywa.blogspot.com" onclick="window.open(this.href);return false;

AndyH
Posts: 6384
Joined: Fri Apr 23, 2010 3:43 pm
Location: San Antonio

Re: "The Cost of Cool". Air conditioning has changed the wor

Wed Oct 24, 2012 4:52 pm

Smidge204 wrote:
AndyH wrote:Efficiency? It's like talking about solar panel efficiency, or 'complaining' that trees are only about 1% efficient. Why do we care if it's free and there's many thousands of times more capacity available than need?
I'm not completely convinced we have enough tappable cooling capacity in free-running water but whatever. Even if we do, efficiency matters because unlike solar panels not everyone has a decent sized stream in their back yard. Those fortunate enough to have such resources may not have enough to meet their cooling needs.
But they may. Considering that it's been done in the past very successfully with enough air generated to make ice, cool refrigerators and run air tools...

Smidge204 wrote:(And efficiency of solar does matter, since the total surface area you need to meet a given power demand is inversely proportional efficiency. More efficient panels means you need less real-estate and consequently lower costs.)
Yes, it can matter if one is short of space. Considering all the warehouses about and parking lots that could be shaded, I'm not really worried about this part of the puzzle at the moment.


Smidge204 wrote:
AndyH wrote:It's very easy to pull air from underground where it's cool and dehumidified and pull it through buildings using a solar chimney. Again - no computers, no electricity - and it automatically works during the day when we need the cooling. It worked in ancient Rome and is working in homes around the world today.
It would be very difficult to pull air from underground around here, considering in some locations the water table is so high the earth practically squirts you in the eye like an overripe grapefruit if you dig your toe in. :lol:
Run it through a water wheel on the way to your eye, then!

Smidge204 wrote:I'd also contend that air that has been cooled with direct contact with water is anything but "dehumidified." It will be at the saturation point. You will have damp, cool air. Gotta warm it up a bit first in the absence of water. Mixing in some fresh outdoor air is a good way to do this providing it's not humid out.
That's fine. Run the air through a heat exchanger on the way into the building - instant dehumidifier.

Consider this cooling tube:

coolngtube.jpg

[Source: Permaculture: A Designers' Manual, Mollison, page 367]

Add a heat exchanger in the tube with a French drain for the condensate. Inject the compressed air downstream of the exchanger. Air is drawn into the house using solar 'convection engine' - no fans, etc.

If there's no compressed air, maybe the 'cold' side if a small window air conditioner in the tube with the 'hot side' and solar panel above ground.

Combining building placement, shading, earth berms, plants, insulation, thermal mass, etc. can significantly reduce the amount of heating/cooling needed. Once the gap narrows, we may be able to use a small solar-powered window air conditioner to do the same job rather than a 5 ton AC system. Check out the benefits of just one item - an adobe building: http://www.toolbase.org/PDF/Techinv/AdobeLatentHeat.pdf
Note that when outside temperatures were 102° F, inside temperatures were 80, F - a 22° difference! (note: With no heating, cooling, overhangs, or insulation in the building)

edit...updated link: http://www.udcinc.org/Adobe;%20Latent%20Heat%20a%20critical%20connection.PDF
/edit

Smidge204 wrote:Edit: For what it's worth, geothermal heat pumps are becoming quite popular around here and would likely be more so if our electricity wasn't so expensive. Geothermal + Solar anyone?
They still use plenty of energy - that's why off-gridders generally stay away from heat pumps. Passive solar is free, the cool of the ground is free, and there are other options that require less energy input to do the same job.


Smidge204 wrote:
AndyH wrote:The oil age allowed us to get very sloppy with energy similar to the way larger microprocessors allowed programmers to freely develop bloatware. But just because we CAN create an application that uses 72.6 quintillion lines of code doesn't mean we HAVE to - and certainly doesn't mean it's the best way to solve the problem.

I agree! But the oil age has also allowed human civilization to spread and flourish in places we previously could not. Bringing an end to the oil age means either finding suitable ways to replace oil, or abandoning much of our civilization. No points for guessing which option I'm in favor of ;)
=Smidge=
Ok then - you keep looking for that oil. :P :lol:

I think we're on the same side of the overall exercise (replace oil without Death Panels ;)), but think we might be evaluating solutions from different directions. Nothing wrong with that!
Last edited by AndyH on Mon Apr 11, 2016 12:11 pm, edited 1 time in total.
"The stupid become extinct."-Bill Mollison
2018 Outlander PHEV
2015 smart Electric Drive (lease ended Feb, 2018)
OpenEVSE Plus DIY

Smidge204
Posts: 940
Joined: Wed Nov 24, 2010 1:42 pm

Re: "The Cost of Cool". Air conditioning has changed the wor

Thu Oct 25, 2012 6:31 am

AndyH wrote:Yes, it can matter if one is short of space. Considering all the warehouses about and parking lots that could be shaded, I'm not really worried about this part of the puzzle at the moment.
Just an analogy, let's not get too caught up in it :P The point is, efficiency matters because even though the resource is free, the rate at which it can be utilized is limited. The more efficiently you can utilize the resource the more benefit you get.

If you can achieve 10,000 BTUs of cooling per hour using completely passive methods, but 20,000 BTUs per hour using active methods, then you can cool twice as much with the same resource. It's a no-brainer in my book.


AndyH wrote:Consider this cooling tube:


Looks like a swamp cooler to me! Just takes up more room.

So how much water do you suppose it would take to evaporatively cool the city of Phoenix, AZ? Been staring at my psychrometric chart here for about 30 minutes and it seems it takes about 2.7 milliliters of water to cool 14 cubic feet of air from 104F/15%RH to 78F/60%RH. If we make some assumptions about how much air needs to be cooled we can get a rough estimate for how much water that would take.

Gonna hazard a guess and say "a lot." I propose there are more important things we need that water for.


AndyH wrote:Add a heat exchanger in the tube with a French drain for the condensate. Inject the compressed air downstream of the exchanger. Air is drawn into the house using solar 'convection engine' - no fans, etc.
There wouldn't be any condensate. In evaporative cooling the enthalpy of the air (BTU/lb) remains the same and so does the dew point temperature. It 'feels cool' because you are putting the sensible heat into latent heat. If you want that water back you'll need to spend more energy - there's no free lunch I'm afraid!

So what happens if you use a heat exchanger? You avoid dumping all that moisture into the space but you pay for it in reduced efficiency - meaning you need more water for the same level of cooling.


AndyH wrote:If there's no compressed air, maybe the 'cold' side if a small window air conditioner in the tube with the 'hot side' and solar panel above ground.
The compressed air is cool because of evaporative effects, not because you are letting the compressed air expand adiabatically. At least that's the case with the water-flow-induced compression which would require hundreds of feet of water column to get any useful effect. Again, no free lunch!


AndyH wrote:Combining building placement, shading, earth berms, plants, insulation, thermal mass, etc. can significantly reduce the amount of heating/cooling needed. Once the gap narrows, we may be able to use a small solar-powered window air conditioner to do the same job rather than a 5 ton AC system
100% agreed, no contest. Good, energy-efficient design is of paramount importance!

But we can't reasonably sustain our current economy, industry and population with adobe and earthen-berm houses. As effective as these strategies are for individuals it does not scale. Dense urban populations are essential for reducing per-capita resource demand, which may seem paradoxical at first but that's how it works out.
=Smidge=

DaveinOlyWA
Posts: 13144
Joined: Sat Apr 24, 2010 7:43 pm
Delivery Date: 16 Feb 2018
Leaf Number: 314199
Location: Olympia, WA
Contact: Website

Re: "The Cost of Cool". Air conditioning has changed the wor

Thu Oct 25, 2012 6:39 am

Andy has a valid argument but like most scenarios, it is not a one size fits all solution. there will be extremes like Phoenix that will not work (where have we heard that one before) but that does not mean that we discount the option for the other 75% of the country where this might be viable.

problem with anything like this is the existing incompatible infrastructure. its not like this stuff can be added on. most of this needed to be torn down and redone from scratch.

but we have TONS of new construction going up all the time and most of it DOES not use these ideas simply because it costs a buck more. once again, its the almighty buck in the short term that wins out.
2011 SL; 44,598 miles. 2013 S; 44,840 miles.2016 S30 deceased. 29,413 miles. 2018 S40; 8743 miles, 485 GIDs, 37.6 kwh 111.39 Ahr , SOH 96.49, Hx 114.98
My Blog; http://daveinolywa.blogspot.com" onclick="window.open(this.href);return false;

jkirkebo
Posts: 400
Joined: Fri Jun 18, 2010 1:51 pm
Delivery Date: 30 Oct 2011
Leaf Number: 007344
Location: Fredrikstad, Norway

Re: "The Cost of Cool". Air conditioning has changed the wor

Thu Oct 25, 2012 8:41 am

Smidge204 wrote:It's a quaint idea and certainly simple in concept and implementation, which has its advantages. Again, though, my gut feeling is you can get more bang for your buck(et) using more modern technologies.


Yeah, like energy wells. I have a 656' deep energy well in my yard which most of the year is connected to my heat pump. But in summer I can use to to cool the house nearly for free. It is a closed circuit in which water (actually 33% bio-ethanol) is circulated by a pump. For cooling the loop is run through two fan coils. One cools the first floor and the second cools our bedrom.

We keep the first floor at about 77degF and the bedroom at 68degF. When everything runs the power consumption is about 200 watts. At night, when only the bedroom is cooled, the pump is controlled by a thermostat and only runs intermittently (the pump is the largest consumers, the fans in the fan coils only use 30-40W). So for warm summer days & nights I might use 2-2,5kWh per day for cooling :)

AndyH
Posts: 6384
Joined: Fri Apr 23, 2010 3:43 pm
Location: San Antonio

Re: "The Cost of Cool". Air conditioning has changed the wor

Thu Oct 25, 2012 1:20 pm

Smidge204 wrote:If you can achieve 10,000 BTUs of cooling per hour using completely passive methods, but 20,000 BTUs per hour using active methods, then you can cool twice as much with the same resource. It's a no-brainer in my book.

I thought you appreciated efficiency? :P If you can bring the temperature of the building down 20° with passive measures, that last 10° of 'active' cooling will be smaller, less expensive, and use less energy than a 100% active solution to drop the temp 30°, right?

Smidge204 wrote:
AndyH wrote:Consider this cooling tube:

Looks like a swamp cooler to me! Just takes up more room.

Yes, this example was tailored to a dry climate and does augment the cooling with some evaporation. But cooling tubes don't have to add humidity. They've been used all over the world since ancient Rome. It's cool underground, and ambient air pulled underground dumps heat on the way to the building. Cooling tubes are standard equipment for Earthships. Air from an Earthship cooling tube measured 75° on a 90° afternoon in S Dakota. This is from a galvanized steel culvert about 40' long - no water, no clay pots. They work in east Texas as well - and nobody there needs added humidity. ;)

Reynolds on cooling tubes:



Smidge204 wrote:So how much water do you suppose it would take to evaporatively cool the city of Phoenix, AZ? Been staring at my psychrometric chart here for about 30 minutes and it seems it takes about 2.7 milliliters of water to cool 14 cubic feet of air from 104F/15%RH to 78F/60%RH. If we make some assumptions about how much air needs to be cooled we can get a rough estimate for how much water that would take.

Gonna hazard a guess and say "a lot." I propose there are more important things we need that water for.

That's fine. Nothing I'm suggesting talks about adding water. I did appreciate my swamp cooler when I lived in Tucson, though. - though it was only sized to cool my house not the entire city. ;)

Smidge204 wrote:
AndyH wrote:Add a heat exchanger in the tube with a French drain for the condensate. Inject the compressed air downstream of the exchanger. Air is drawn into the house using solar 'convection engine' - no fans, etc.
There wouldn't be any condensate. In evaporative cooling the enthalpy of the air (BTU/lb) remains the same and so does the dew point temperature. It 'feels cool' because you are putting the sensible heat into latent heat. If you want that water back you'll need to spend more energy - there's no free lunch I'm afraid!

So what happens if you use a heat exchanger? You avoid dumping all that moisture into the space but you pay for it in reduced efficiency - meaning you need more water for the same level of cooling.

I'm not sure how we got here. I'm not talking about adding any water. I just wondered about running cooler air thru a heat exchanger before releasing it into the cooling tube. The formerly compressed air will cool as it expands - this is the source of the compressed-air chilling - not moisture.


AndyH wrote:If there's no compressed air, maybe the 'cold' side if a small window air conditioner in the tube with the 'hot side' and solar panel above ground.
The compressed air is cool because of evaporative effects, not because you are letting the compressed air expand adiabatically. At least that's the case with the water-flow-induced compression which would require hundreds of feet of water column to get any useful effect. Again, no free lunch![/quote]
We're talking about a use of compressed air developed from a trompe - which is air compressed by injecting it into a stream of water that's heading straight down 300'. The water dumps the air underground and then returns to the surface on its own and continues downhill where it can encounter another trompe. The air heats as it compresses, but the heat is taken away by the water. The air is compressed and cool when stored, not compressed and hot as with a mechanical air compressor. When the compressed air is released in a room, it cools as it expands. Adiabatic not evaporation. The lunch is free until we can meter gravity. :lol:
Smidge204 wrote:
AndyH wrote:Combining building placement, shading, earth berms, plants, insulation, thermal mass, etc. can significantly reduce the amount of heating/cooling needed. Once the gap narrows, we may be able to use a small solar-powered window air conditioner to do the same job rather than a 5 ton AC system
100% agreed, no contest. Good, energy-efficient design is of paramount importance!

But we can't reasonably sustain our current economy, industry and population with adobe and earthen-berm houses. As effective as these strategies are for individuals it does not scale. Dense urban populations are essential for reducing per-capita resource demand, which may seem paradoxical at first but that's how it works out.
=Smidge=

There is nothing remotely sustainable about our current economy or the way we do business. There are designs for entire cities that use bermed passive solar buildings, however. Native people have been living in high-density passive structures for thousands of years, and the guy that developed Earthships has designed and built high-density housing that can be used up mountains or to form cities. It scales nicely, though it won't look like Los Angeles. ;)

An air conditioner designed during the days of cheap energy can be very inefficient - it's built to do an 'acceptable' amount of work for an 'acceptable' amount of time while using an 'acceptable' amount of inexpensive power at the lowest price. Let's put this air conditioning model at one end of a line - say negative 100. Add a few generations of Energy Star and we can evolve the air conditioner thru -90 to -75. Yes, it's progress, but it's painfully slow and we're expending a lot of design energy to stretch a robber band that's anchored at that original -100 point. Cooling tubes, appropriate materials, passive solar, etc. can reduce energy demand more than 80% from the beginning.

Put another way, conventional design and economics says that efficiency costs more, so we can afford to add only so many LED lights and ground source heat pumps before we're out of money. Yet Reynolds (Earthship), Lovins (RMI) and others show that efficient design from the start turns those two dimes ;) over - in this new world, more efficiency costs less.

edit... Here's an example of a building in a cold temperate climate that uses a number of different techniques. Note the refrigerator:
(Fast forward to 20:30 or hit this link: http://www.youtube.com/watch?v=jGkHH4iFA0I&t=20m30s

"The stupid become extinct."-Bill Mollison
2018 Outlander PHEV
2015 smart Electric Drive (lease ended Feb, 2018)
OpenEVSE Plus DIY

AndyH
Posts: 6384
Joined: Fri Apr 23, 2010 3:43 pm
Location: San Antonio

Re: "The Cost of Cool". Air conditioning has changed the wor

Thu Oct 25, 2012 10:22 pm

Smidge204 wrote:I'd also contend that air that has been cooled with direct contact with water is anything but "dehumidified." It will be at the saturation point. You will have damp, cool air. Gotta warm it up a bit first in the absence of water. Mixing in some fresh outdoor air is a good way to do this providing it's not humid out.

Ok - this has been bothering me. Got it now, I think!

Air compressed in a trompe is in contact with water, but it's compressed and cool. Yes, maybe it's at or near the saturation point, but it's not going to be used in this condition.

Releasing the air lowers the pressure - it gets cold enough to make ice. Now the expanding air is no longer saturated - if it's not mixed with outside air is RH continues to drop. This is all adiabatic.

(Switching gears to add the cooling tube...)

That's why I suggested running the compressed air through a coil in the cooling tube - a cold coil exposed to ambient air is the definition of a dehumidifier - moisture from the warmer air flowing through the cooling tube will condense on the cold coil. Releasing the partially compressed air into the cooling tube downstream of the coil will continue the cooling of the air that finally enters the building. I'm not sure how well this would work though as it would probably ice up the coil. We'd likely have to separate the compressed air stream into two - larger volume for cooling and a smaller volume for the dehumidifier heat exchanger.

With good design, though, in a desert climate (Phoenix!) the cooling tube as depicted in the image snagged from the Permaculture Designer's Manual is exactly all that's needed - no compressed air is necessary.

Image

Looking at it again, it's a three stage system. Digging down a few meters below the surface and the ground stays around 45-50°F year round - so the basic cooling tube/tunnel will do most of the work. The shade/plants cool the area around the inlet, and the pot inside the building provides a bit of evaporative cooling and much appreciated humidity.

Cooling tubes are used in desert hospitals in Australia (Alice Springs for one) and in school buildings in Jordan. Desert animals automatically build them as part of their tunnel system, as do termites in their mounds.

Sorry to add confusion by inserting the cooling tube into the middle of a compressed air thought process. :oops:
"The stupid become extinct."-Bill Mollison
2018 Outlander PHEV
2015 smart Electric Drive (lease ended Feb, 2018)
OpenEVSE Plus DIY

Return to “Environmental Issues”