The answer to the OP is that the higher you can set the AC for the longest period of time is the cheapest. Period.

The heat flow out of the house via the AC is exactly equal to the heat flux into the house.

The heat flux into the house is exactly proportional to Integral deltaT dT.

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Bill Slugg
Albany, GA

What does that have to do with anything?

Man, if the power ever goes out, Americans will be doomed to sweat to death and whine about it all day.

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Fields of Space

LOGIC, n.
The art of thinking and reasoning in strict accordance with the limitations and incapacities of the human misunderstanding.

In the Year 2525.

"One small step for (a) man. One giant leap for mankind".

If an astronaut doesn't need good grammar, niether does you.

Host of Seraphim

That might be true for some people and in some cases, but not for me. I lived in New Orleans for two years and had my headaches constantly (that's when I first realized the seriousness of my problem).

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At night the stars put on a show for free (Carole King)

One Earth, One Sky - IYA 2009

Maybe it wasn't the heat, but the hurricanes.

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A person's name, or a mark representing it, as signed personally or by deputy, as in subscribing a letter or other document.

They won't even know how to whine without the internet.

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Numbers are not case sensitive. (me)

With Laptops and UPS' who needs an active power source?

There's been an awful lot of odd physics in this thread (says an economist), not just the quote here.

Aircon units are heat-pumps, and can therefore shift substantially more energy than they consume. From what I can see, typical portable aircon units have an "efficiency" (SEER) of around 300%, and installed units in buildings in some US states are REQUIRED to have an efficiency of more than 1000% (ie SEER > 10).

If it takes longer to cool a room by 10 degrees than heat it up by 10 degrees, that's simply because your heating system has a higher output than your aircon. I don't agree with whoever said that heating a building is easier than cooling it because the nature of the losses is different between heating and cooling. A object will have more or less the same propensity to return itself to its equilibrium temperature whichever direction the temperature disturbance is in. Of course, if our building is still a long way from equilibrium and we not only have to cool it back to comfort but also work against the heat input that is heating it up, then that is more work, but in general heating/cooling systems change the indoor temp much more quickly than the application of the exterior effects, or at least they ought to if you have a sensible amount of insulation. In general when we heat a building it is usually further from its equilibrium temperature than when we cool it (ie winters are further from comfort temp than summers in most places) so actually the summer cooling ought to be easier than the winter heating.

Also whoever said that there is only conduction in cooling is wrong. A clear sky is a powerful radiative cooler. Look up radiation frost here. http://en.wikipedia.org/wiki/Frost

that's something most of us don't think about.




I remember as a child being yelled at for leaving the front door open, "what were you born in a barn?" was one standard response. Another was, "are you trying to cool Texas?" Of course the reply to that was "nope, trying to heat it up"

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"I will do my best to understand and explain the universe from big to small without invoking miracles, unrepeatable events, or divine intervention. In place of those things I will use observations, mathematics, and science."


-Cross
My travel blog

Some of my Astrophotography


Those that lack education have a hard time understanding its value. - Cross

This remark wasn't necessary, Ivan. Just make your point.

Your argument can be rebutted, but given your preamble, I'll not be the one to do it.

My own experience is mucho savings by using the programmable thermostat to reduce use when not at home and when sleeping.

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Don of Borg - Cool, Calm, Collective.

"Within the next generation I believe that the world's leaders will discover that infant conditioning and narco-hypnosis are more efficient, as instruments of government, than clubs and prisons, and that the lust for power can be just as completely satisfied by suggesting people into loving their servitude as by flogging them and kicking them into obedience." -- Aldous Huxley

Another issue is that you make your electric utility company a lot happier by minimizing your electricity usage during peak hours. I'm sure this is an oversimplification, but the utility is going to organize its sources of electricity by cost, running the cheapest ones all the time and only kicking in the most expensive ones when absolutely necessary. So if you minimize your electricity usage during the hottest hours (3-7 pm in this area), you're saving the utility money and, in the end, yourself as well since they can keep the rates lower. That's what my wife and I try to do (which is easy for me since I don't usually get home from work until around 7 pm!)

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Everything I need to know I learned through Googling.