Southern "hot" cities more energy sustainable than northern "cold" cities?

[Ted King]

http://www.theatlanticcities.com/housing...hink/5115/

A closer look at the math of indoor climate control suggests that, at least on this last point, southern cities may in fact be more sustainable than their older, bitterly colder brethren in the north. We're looking at you, Minneapolis. Michael Sivak, a research professor at the University of Michigan, compared Minnesota's largest city (and the coldest major metro in the U.S.) with Miami (our warmest metro on average), looking at the energy it takes for the two just to keep themselves at livable temperatures.

Minneapolis – just talking here about heating and cooling – is three-and-a-half times as energy demanding as Miami, a finding that will likely shock people there (or in Milwaukee or Buffalo) who've long prided themselves on life without A/C.

I don't know about the validity of this researcher's methodology (at least his study uses quantifiable factors), but the result is interesting and not one I would have expected. I wonder of other factors overwhelm the overall energy use difference between northern and southern cities (generally - a northern city on the coast is often not as cold as a northern city well inland, for example).

[cbelt3]

Well DUH. Heat requires more energy than just moving air around, if you include the energy cost of burning fuel to make the heat. Why this is a lightbulb moment is beyond me.

[Ted King]

cbelt3 wrote:
Well DUH. Heat requires more energy than just moving air around, if you include the energy cost of burning fuel to make the heat. Why this is a lightbulb moment is beyond me.

I think people in Phoenix are doing more than "moving air around" to keep cool. Do air conditioner compressors and condensers run without power?

[Bill in NC]

Heat pumps are much more efficient than any boiler or furnace.

[mattkime]

does it matter?

Minneapolis will improve with global warming and Miami will be under water.

[Gutenberg]

When you talk about sustainability in southern Arizona and southern California you have to talk about water as well. It is not just power there. But I can certainly accept Miami as more energy-saving than Minny/St. Paul, which suffers extremes at both ends of the thermometer.

[Black]

Manufacturers have been moving south to avoid heating costs for decades.

Ted King wrote:
[quote=cbelt3]
Well DUH. Heat requires more energy than just moving air around, if you include the energy cost of burning fuel to make the heat. Why this is a lightbulb moment is beyond me.

I think people in Phoenix are doing more than "moving air around" to keep cool. Do air conditioner compressors and condensers run without power?
Good point.

[davester]

That article way overreached on the basis of a very small and limited piece of modeling. The researcher created a very simple model of energy inputs to temperature based on climate degree days at two locations, and assumed that all other factors were equal. He did not attempt to calibrate his model with real data. I do computer modeling quite often, and in my experience, an uncalibrated model is useful for...NOTHING.

[Ted King]

davester wrote:
I do computer modeling quite often, and in my experience, an uncalibrated model is useful for...NOTHING.

Thanks for the informed critique of the article. Just as your seat-of-the-pance rough guess, do you think overall energy consumption for houses of equal net thermal exchange rate* between inside and out are generally greater in northern regions, less or about roughly the same as much more southernly regions? Or is there just too many unknowns for you to feel comfortable even giving a guess?


*I just made that up - I hope it makes sense.

[Ca Bob]

Since air conditioners are, in part, heat engines (they compress a gas, allow it to cool to about ambient, and then allow it to expand, which results in cooling), the overall efficiency of an air conditioner is relatively low. The difference between a Miami or Phoenix and a Minneapolis or Fargo, I think, is that the difference between the temperature extreme and what we think of as comfortable might go from 70 degrees in Minneapolis to maybe 18 degrees in Miami. In other words, if it is 98 degrees out, you only have to cool by 16 degrees to feel comfortable, but if it is minus 5, there is a much longer way to go. Figure that in Minneapolis, the temperature can be anywhere from near freezing to well below freezing for 4 months of the year, that is a lot of heat to provide.