Newsgroups: sci.energy

 |:  |Bo Curry (curry@hplred.HP.COM) wrote:
 |:  |: P.S. I have never had air conditioning in my car, even during
 |:  |: the 7+ years I lived in and about Atlanta. The claim that A/C
 |:  |: is a "necessity" is, quite simply, wrong.
 |:  |
 |:  |hinz@picard.med.ge.com (Dave Hinz) writes:
 |:  |In other words, you have been _harming_ the environment by wasting more
 |:  |gasoline, due to the parasitic drag induced by having your car's windows
 |:  |open.  
 |:  |Ah, the misguided do-gooder.  Perhaps the worst kind.
 |:
 |: Bo Curry (curry@hplred.HP.COM) responded:
 |: Careful Dave, your agenda is showing. Since you know nothing about what
 |: car(s) I was driving, or at what speeds, you have no idea whether your
 |: factual claim is true. You don't even know whether my car *had* windows.
 |: Since you know nothing about my motivations, you have no idea whether your
 |: personal characterization is true. In other words, you're talking through
 |: your hat.
 |: 
 |
 |hinz@picard.med.ge.com (Dave Hinz) replies:
 |Oh, pardon me.  I just assumed that your car was a gasoline-powered one.  I
 |guess being deisel powered, or cng powered, or alcohol powered, or whatever,
 |makes all the difference in the world.
 |

It doesn't matter (much) what fuel the car uses. Computations of aerodynamic
drag depend most strongly on speed and on body design, and to a lesser degree
on road surface. The effect on drag of rolling down a window depends on
these factors, as well as the surface area, angle, and shielding of the
open part of the window. Besides these variables, the relation between
drag and fuel consumption (MPG) depends on the size, efficiency and
maintenance of the engine, drive train, etc.
In addition, since you were implicitly comparing
delta(MPG | open windows) with delta(MPG | A/C),
you have to know something about the latter. dDlta(MPG | A/C) depends
strongly on the delta(T) (i.e. ambient, including any heat concentration
effects vs A/C setpoint). It also depends strongly on A/C design and
level of maintenance.

Your "factual claim" was that:

 "[Bo has] been _harming_ the environment by wasting more gasoline,
  due to the parasitic drag induced by having [his] car's windows open."

Your assumptions are:
    a) I habitually drove with the window(s) open, AND
    b) The delta(MPG | drag) caused by (a) exceeded the delta(MPG | A/C)
       which I would have experienced had I bought and operated an A/C.

I claim that you have no idea whatsoever if these assumptions are true.
They clearly aren't always true: for example, at 25 MPH, delta(MPG | drag)
due to opening a window has a very small effect on MPG, which would certainly
be exceeded by an A/C working over any substantial temperature range.
I know that Gary Coffman posted some old numbers for delta(MPG | drag),
but what do those numbers mean? What assumptions were made? Presumably
they're averages over something, but what? I don't know, and you don't
know either.

 |I also assumed that you were driving something which has some degree of
 |aerodynamic design, that is, something that isn't a semi.  Again, I beg your
 |pardon.
 |
 |OK, so what I am led to believe by your post is that you are driving a car
 |with no windows, not gasoline powered, that has a coefficient of drag 
 |approaching infinity, right?  Or have I misread you?
 |

Do you think these are the only circumstaances which would falsify your
assumptions above? If you do think so, why?
I would think that driving an average pre-1979 US car, mostly in urban traffic,
would falsify (b). a definitive answer to this question would require more
research than I'm willing to do. Notice that I'm not insisting that your
assumptions are false, only that you have no reason to believe that they're
true.

In any case, my original claim (that my experience demonstrates that A/C
is not a "necessity") depends neither on the hypothetical environmental
devastation wrought by open windows, nor on my motivations. It still stands.

 |BTW, just what is my agenda?  What is it you are assuming?  Just curious.

 You wrote:
 "Ah, the misguided do-gooder.  Perhaps the worst kind."

Your claim that I'm "misguided" depends not only on your dubious factual
claims, but also on some assumption about my motives for not having an A/C.
Your argument seems to be:
   1. Bo eschewed air conditioning in his car *because* he believed that
      this would help protect the environment.
   2. However, lack of A/C caused him to burn more gasoline, which
   3. was in fact *more* harmful to the environment than the A/C, including
      its manufacturing, energy use, and waste coolant.
   
   C. Therefore, Bo's belief was false ("misguided").
  
As I pointed out, claim 2 is dubious, and claim 3 might be false even if
claim 2 were true. Claim 1 is completely unsubstantiated. Except for the
fact that all of its premises are questionable or false, the argument
seems sound.

So, collect some data, do some arithmetic, and you might be able to
convince me that my actions harmed the environment, although I doubt it.
You still need to know something about my motivations before you can
reasonably claim I'm a "misguided do-gooder".

About your agenda:

People who season tidbits of data (Gary Coffman's numbers) liberally with
unwarranted assumptions to produce strenuous conclusions are usually
operating from an agenda. "Do-gooder" is one of the code-words employed by a
particular class of libertarian or anti-environmental agendas, as
typified by our goodbuddy JdeA and his fellow Luddites. Admittedly not
as clear an indication as his pet terms, but you also suffered somewhat
from guilt by association.

Hope that helps.

Bo Curry
Eco-Nazis Against Gun Control
From: curry@hplred.HP.COM (Bo Curry)
Date: Thu, 20 Aug 1992 19:36:45 GMT
Subject: Re: Re: Running out of oil ->NEVER<-
Organization: Hewlett Packard Labs, Palo Alto CA