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Discussion Starter · #1 ·
:)
 

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Your going to have a lot of "variables" and sub calculations doing this...

The "Home" calc's:

1) "R" rating of the isulation on the home corresponding to thermal heat transfer. (heat loss rate in BTUs)

2) Desired heat normaly applied to the thermostat while at home.

3) Cost of heating oil/electricity (for some)

4) The "mean" average of outside temp during the duration of the experiment. (Wind chill factor will have to be included as well)


The Car calc's:

1) "All of the above with the exception of:"

a. Swap heating oil for gas price
b. Add in average speed of Prius and add to "wind chill" calculations
c. How much of the fuel "gas" is being consumed that is not heat.
Moving the car, charging battery, etc.

OR-

You could just set both temps the same for car and home, buy 20 bucks worth of heating oil and twenty worth of gas and see how "long" you stay warm for each! :lol:....Have fun....and let us know what happens!
 

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Might save you all the trouble with an observation. Congress has adjourned their investigation of the "oil industry" and the price per gallon just jumped ten cents in one week here. And last week I got a load of heating oil at $2.40/gallon and gas was selling at $2.09 and is now 2.19.

Get a good coat!

And now three tanks of gas after my "recall job completed" I am getting 3 MPG less.
 

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You have to consider that in the Prius, you are conditioning a much smaller volume than you are for your home. So, in this case, you would need to consider the cost per cubic foot or meter.
 

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Discussion Starter · #6 ·
:)
 

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Well... if you gotta know, then you need to do a lot of calculations. Go to the library and get the latest ASHRAE* book for calculating heat transfer for buildings. Your home heat loss is dependent on outside temp, inside temp, home construction and insulation, type of windows, roof area, wall area, window area, floor area, wind speed, and the all-important infiltration losses. These can vary a lot depending on construction type and age of home. I've calculated a couple houses -- it'll keep you busy for a several hours if you know basic mechanical engineering heat transfer. It may take several days if you have to learn that as well.

Undoubtedly it is much cheaper to heat a small car, even though it's not well insulated, than a house. Not sure what the R-values are for cars, but you can probably estimate it with the ASHRAE info.

The energy of moving the car around needs to be added, unless you are happy with staying still. There will be lots of heat loss in the engine compartment, plus the Prius will do other "strange" things to keep emissions as low as possible.

This would be an good senior project for a Mechanical Engineering Heat Transfer course. Well, it's pretty academic, nobody in their right mind would drive around all night just to save money on heating their home. Goooooooooood luck!

* American Society of Heating, Refrigeration, and Airconditioning Engineers
 

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But polar bears and bladder problems might be another issue.
 

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Polar Bear, no need to bother DanMan to learn the cubic footage. All you need to do is crack your window a little, fill the Prius up with water from your hose, and then siphon it out into one-gallon milk containers. There are 7.48 gallons of water in a cubic foot. Of course, you won't be able to fill all the way to the top, but this space should just about balance the amount of water that will be absorbed by the seats, etc.

Note: I strongly suggest you first disconnect the main battery. Otherwise you may void the warranty.
 

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I have come up with a lot of crazy cost analysis figures but this one could prove to be both the hardest to figure out and craziest!

just off the top of my head the variables you would have to consider

1 the heat transfer dufference between the house and the car
2 the wear on the engine vs. the wear on the heater/heatpump/furnace/fireplace...
3 the calculation as danman stated the cost per cubic foot of air heated

and so no


this just might keep me up tonight :p
 

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"hyperion's suggestion of a "good coat" opens up an intriguing possibility. Instead of just a bra on the front, it is possible an entire "coat" of one of these new miracle materials, worn by the Prius, would provide excellent insulation for the car, making the heating (& cooling) much more efficient. "



May I humbly suggest having Mrs. Polar Bear wrap the prius in tin foil after you have ensconced yourself inside? Make sure the shiny side faces inward to reflect the heat back in towards yourself! :idea: [/b]
 

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Discussion Starter · #13 ·
GlacierBobby said:
Surely a polar bear dosn't any external heating arrangements!
True ! but a FAKE Polar Bear might. :(
 

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Discussion Starter · #14 ·
:)
 

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DanMan32 has already determined the key point, the much smaller volume needed to heat in the Prius.

Does this discrepancy in needed heating capacity favor the Prius? My initial guess is that it would. The efficiency of the Prius at heating is probably much worse than the furnace, but that is offset by the greatly reduced volume of air needing to be heated. Also, you could modify the heater of the car to have a much larger heater core, since the focus would shift from mpg to degrees of increase per cubic foot. If you ran it back to the cargo area you could even have radiant floor heating.

Now, try it with keeping cool in the summer in Florida and it might be a different story. Kind of like living in a mobile home paying hundreds of dollars a month running three little window air conditioners, as opposed to running one efficient one in a larger but much better insulated home.

Also, I think if that officer saw that bottle of Jim Beam opened, no matter if you're moving or not, you're in trouble. Most places have an open container law, although now I think restaurants have been able to recork the bottle so people didn't have the incentive to finish it before going home, since they had already paid for it.
 

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An04Prius said:
With natural gas and home heating oil prices skyrocketing, while gasoline prices are dipping a bit, I was wondering...would it be cheaper to drive around in my Priius keeping warm instead of staying home running the furnace ? Let's assume an average temp of 70 degrees either place one has chosen to "reside", and no heating at all in the place one has chosen to not reside. Adjustments might have to be made for places like Minn, where some minimum heat must be maintained to keep the pipes from freezing.

I need help. I havn't the vaguest idea how to start the calculation to determine this. However, I am sure mpg junkies on this site (for whom I have a great deal of respect for their ingenuity, numerical talent, chart making and record keeping patience) can come up with something for all of us to contemplate, with multiple variables at different price points for various heating fuels in the home and gasoline.

Of course, we will all have to individually weight the non numerical aspects for ourselves, for example, there are less entertainment & dining options in a moving Prius than at home (although a stationary one would expand the options).

I appreciate anyone who would like to take a stab at it.
Have you ever considered the Prius as a great vehicle to drive out on the ice and use as a portable "ice shanty" for winter fishing? You got warmth, mobility, little pollution, etc. Drilling a 6" diameter hole in the floor board means you wouldn't even have to leave your Prius Fishmobile!
 

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Discussion Starter · #17 ·
:wink:
 

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I think the Prius burns around 0.2 gallons/hour at idle. On a somewhat cold day it would probably idle 1/3 of the time to keep warm. So that would burn 1.6 gallons per day. Gas today was $2.159 at a local station. So that's $3.4544 per day or about $100 per month. My house runs about $200/month to heat in the winter. So if I was willing to give up almost all my living space, I could save about $100/month. I might even save more, since my whole family of 4 would need to move into the Prius. That many warm bodies would reduce the amount of heat the Prius needed to generate.

I think I'll pass.
 

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Discussion Starter · #19 ·
:wink:
 

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Discussion Starter · #20 ·
:wink:
 
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