Turning down the AC
Posted by Yankee on March 9, 2006 - 10:55am
Topic: Demand/Consumption
Tags: air conditioning, conservation, fuel, gasoline [list all tags]
The New York Times reports (from the other day, but we didn't cover it, did we?):
The Department of Energy's National Renewable Energy Laboratory reported on Thursday that if every car and truck on America's roads was equipped with ventilated seats, air-conditioning-related gasoline consumption could be reduced by 7.5 percent, thus saving 522 million gallons of fuel per year.While I'm at it, I'll just throw this out there. If you're driving on a highway at 60mph, which is more fuel efficient: turning on the AC, or opening the windows? In my experience, this question always causes something of a disagreement.The seats tested have two built-in fans that suck warm air and moisture through their perforated leather and send it away from the driver or passenger.
Ventilated seats make drivers feel cooler, so they could save fuel by turning their air-conditioners down a notch, in theory.
And you can also use this as an open thread.
[editor's note, by Prof. Goose]Also, a heads up (hat tip: peakoil.com) on a CNN special on peak oil which will be aired Saturday, March 18, 8pm, anchored by Frank Sesno, and is called "We Were Warned: Tomorrow's oil crisis." (brief description here)
Some very interesting stuff at the new Hubbert tribute site. Personal as well as peak oil-related.
have some really interesting comments.
I was a high school senior in 1956.
http://www.prosefights.org/shattuck/shattuck.htm
ARTIST: Kansas
TITLE: Portrait (He Knew)
Lyrics and Chords
[Capo 3]
He had a thousand ideas
You might have heard his name
He lived alone with his vision
Not looking for fortune and fame
Never said too much to speak of
He was off on another plane
The words that he said were a mystery
Nobody's sure he was sane
/ Bm - / G - / D - / E G / :
{Refrain}
But he knew
He knew more than me or you
No one could see his view
Where was he going to
/ Bm / GE Bm / / G E /
He was in search of an answer
The nature of what we are
He was trying to do it a new way
He was bright as a star
But nobody understood him
"His numbers are not the way"
He's lost in the deepest enigma
Which no one's unraveled today
{Refrain}
And he tried
But before he could tell us he died
When he left us the people cried
Oh, where was he going to
He had a different idea
A glimpse of the master plan
He could see into the future
A true visionary man
But there's something he never told us
It died when he went away
If only he could have been with us
No telling what he might say
{Refrain}
But he knew
You could tell by the picture he drew
It was totally something new
Oh, where was he going to
I recall a funny comment by a Daimler engineer saying that they put in sunroofs so you wouldn't need AC, but Americans insisted on both.
Just joking, Dick, Rummy, just joking. Hm. Shouldn't be giving these guys ideas, should I?
We really have to do something about road rage.
I often see people get into a closed up, boiling hot car and turn on the AC without opening the windows at all. This puts a huge load on the AC. If they would just run a block or two with the windows open, it would make a lot of difference.
In Iraq, gunners man turrets that are basically sunroofs in the Hummers. By armoring a car with Plexiglas , the turret is invaluable in road warfare. (Think of The Gauntlet with Clint Eastwood armoring the bus cockpit but replace steel with Plexi.)
The main usefulness is if a Road Warrior -ish future develops.
I also use LEDs for marker lights and am considering HID conversion for headlights (brighter, 35 watts instead of 55 watts on low for each headlight).
Synthetic fluids all round. Mobil 1 in engine & differential, M-B in manual transmission, Valvoline in Power Steering and brakes.
Result 31 mpg city, 35 to 42 mpg highway (depending upon speed) and a car that will last my lifetime, barring accidents.
Sitting still in heavy traffic would be an obvious exception, but I keep the windows closed in that situation anyway, ever since the time I was stopped next to badly-tuned midsize truck that blew a dense cloud of diesel smoke directly in my open window :^)
And then what do they breath? Bottled air? A minority of people have cabin air filtration systems. How many of them work effectively, or are in working order, is moot.
And then there are the voc's generated by the various materials out of which the vehicle interior is manufactured.
It's all too much. I think I'll have another cigarette.
doug gabelmann
ottawa
Another point not often mentioned is that you probably wouldn't open your windows all the way at 60+ MPH, especially not at 75 or 80 like people drive around here. It's way too windy and noisy. So this introduces another variable in the comparison: windows cracked open an inch or two vs closed vs open all the way. My guess is that opening them enough to ventilate the car nicely is not going to create as much drag as opening them all the way.
The auto makers started doing away with those nice little side window vent wings during the late 1960 and early 1970s. It's a shame, because they provided very good ventilation in an un-airconditioned car. Those 'crotch-cooler' vents on either side under the dash also helped a great deal. Some of the cars from the 1940s and early fifties were even better in that regard, as some had these moveable vents in the center of the hood near the windshield that you could raise or lower.
As to whether there is more energy lost at 60 mph with the windows open or with the AC on, I'd say that the answer is not so clear cut. It depends on the shape of the car, whether all the window are wide open, and how large of an AC you have an how high you have it turned up. If you're talking about over 70 mph, I suspect the window-open mode would expend more energy, If it's just 60 mph or below, I'd say that it depends.
Still, it's well to note the effect. Keep in mind that all the windows do not have to be fully open for good flow-through ventilation; you just have to have well-designed vents. And the idea of positive ventilation for the seats seems to have merit. (Just make sure that the exhaust from the front seats is not directed onto the rear-seat passengers!)
Remember that power required for a given speed goes up as the third power (cube) of the speed, as far as aerodynamic drag. That is to say if you double your speed, you require eight times more power to maintain that speed. This cube term really magnifies the effect of just cutting down your speed a little bit to save gas.
It is not correct that the total power required to proper a car increases as the cube of the speed. The total power to propel a car is composed of several components, the main ones being: i) rolling friction, ii) engine friction and other engine losses, and iii) aerodynamic drag. The first two rise more or less linearly with speed. It is only the power component consisting of aerodynamic drag that rises with the cube of the speed.
So, at low speeds (say up to about 40 mph, depending on the drag coefficient of the specific car) the power rises only slightly steeper than linear. But as the speed increases, aerodynamic drag starts to predominate and the speed/power relationship begins to move more into the cube rule-regime. That is why even very light race cars need very powerful engines.
The so-called cube-rule holds a little better for ships, but even there it is not clear cut. At low speeds a long slender ship will actually use more power than a more stubby one of the same displacement because it has more wetted area and hence more surface friction. But as the speed goes up, the power expended in pushing water aside and in wave making begins to predominate and the long slender ship will use less power for the same speed. It gets very expensive to get a ship to go over a certain characteristic speed that is determined by its length and hydrodynamic form.
Doubling the power will roughly double the rate of fuel consumption, but not the amount of fuel consumed in traveling a given distance. The reason is that in the high-power case, the vehicle is traveling faster, and hence covers the same distance in a shorter period of time, and hence the higher rate of fuel consumption takes place over a shorter amount of time. While it nowhere evens out, it's important to realize that doubling the power does not halve your gas mileage. (It makes it considerably worse, but not by a factor or 2).
Then ditto for all the other seats that might have a sitter sometime. Sell your AC to the uninformed to regain the entire cost of your new innovation.
I think you meant "Peltier", not stirling. ^_^;
With the average metabolism being 200 calories/day, that's about 80 watts. Create a source of hypothermia and insulate the rest of your body, and you'll need very little A/C to keep cool.
This is one reason I like to shift to neutral when coasting downhill; the engine burns a lot less fuel ticking over at 800 RPM than overcoming friction at road speed of 2100.
"Vice President Dick Cheney said Tuesday that Iran will not be allowed to have a nuclear weapon and warned "the United States is keeping all options on the table in addressing the irresponsible conduct of the regime."
Cheney said the Iranian government "continues to defy the world with its nuclear ambitions" and that the issue may soon go before the U.N. Security Council.
"The Iranian regime needs to know that if it stays on its present course, the international community is prepared to impose meaningful consequences," Cheney said in a speech to the American Israel Public Affairs Committee, an influential pro-Israel lobbying group."
"The regime has shown it cannot be trusted. It hid its nuclear activities for two decades from the international community. It has refused to comply with its international obligations. This is about the regime and its behavior. That's what this is about and that's what our focus is."
http://www.cnn.com/2006/POLITICS/03/07/us.iran.ap/index.html
You may want to replace "Iran", "nuclear weapons" with "Iraq" and "WMD" and it all sounds too familair. Especially that last sentence I quote gives me the shivers. Deja-vu!
Attacking Iran may sound impossible, implausable, irrational, immortal, economic suicide etc.
The present US administration however are champions making decisions with such characteristics.
Or?
What better way to mask or phostpone PO by wrecking the world economy and take vast amounts of oil out of production (like happened in Iraq) by attacking Iran (and possible closure of the Strait of Hormuz)?
This is speculation but the Bush administration IS Peak Oil informed. I could go on and speculate attacking Iran is just part of a wider, long term strategic objective.
Sorry folks. It's gonna happen. Wait for the UN to become "irrelevant" again.
The U.N. is steeped in corruption from top to bottom and utterly ineffective in stopping wars. Holy Shishkebabs, you think the sainted Kofi Anan didn't know what junior was up to? If so, that bridge in Brooklyn is still for sale. And for you, a special price.
Now we talk about it, the US itself is represented by someone who has repeatedly called the UN irrelevant. That should tell something.
Glad you aggree with me Granddad.
But when you think of it if there was not UN, the majors would be starting to shoot without even bothering for justifications. At least it gives some time and a chance for sanity, IMO.
This is speculation but the Bush administration IS Peak Oil informed."
Bolten at the U.N. is saying," tangiable consequences".
I'm not saying/agreeing the train has left the staion, but the engine is running; however if the price increases that will be a driver so that oil is not the focus on their watch. Yes , the train may have already left the station. I pray it hasn't/won't.
It's easy to say stuff like "face it, it's gonna happen," or "no way, they wouldn't dare," but that's just talk. People in these markets are backing up their opinions with real money. That automatically gives them more credibility. And the market averages everyone's opinion to come up with an overall consensus, which is another thing that's hard to get just by reading different people's opinions.
http://www.intrade.com/jsp/intrade/contractSearch/searchPageBuilder.jsp?z=1141929857810&grpID=44 28
These are the current odds for an air strike on Iraq by the following dates:
Jun 30, 2006 ------ 10.7% - 11.3%
Dec 31, 2006 ------ 23.6% - 24.7%
Mar 31, 2007 ------ 33.0% - 34.4%
If I recall correctly, you posted much the same sort of thing last week. (?)
While the March 31, 2007 odds of 33% look tempting, I have a real problem with this whole concept of betting on war, largely because it reduces war to the level of a sporting event, which I find vaguely obscene.
In case you've chosen to forget, a massive air attack on Iran will result in probably thousands of innocent people being killed or permanently maimed. Thus, if I were to make a wager that the US/Israel will attack Iran by such-and-such, it would be unavoidable that I would consciously or unconsciously be rooting for the attack to take place. By so rooting for an attack to take place, I would in essence be rooting for people to be killed and maimed, because the latter is unavoidably connected to the former.
Moral and ethical considerations aside, I just don't want to put myself in that position. Particularly since my nextdoor neighbor's kid will be leaving for Iraq in April to fly helicopters. If win my bet and he should come back home through Dover AFB, I don't want to feel that I somehow benefited by his death. I'm not by nature a superstitious person, but in this case, I just think it's bad luck all around.