opinion

Allhands: Why 120 degrees in Phoenix is better than -30 degrees in Boston

Pity those poor people on the East Coast this weekend, with their wind chills plunging to 30 degrees below zero.

Or, actually, don't pity them. It's sort of an Arizona pastime to call our frigid brethren and gloat that it's 70-plus degrees.

We don't care that they'll dish it right back when it's 110 degrees or higher for the 30th day in a row. We gloat anyway.

So, when you make those calls, add this:

It's better, from a heating and cooling standpoint, to endure an extreme 120 degrees in Phoenix than an extreme -30 degrees in Boston.

Yeah, I know. There's no hard and fast data to prove this. Actually, when you call experts to talk about it, they tell you that there are too many variables among states to make these sorts of comparisons.

Homes must be the same size, they say, with the same insulation, the same number of windows, the same orientation to the sun and wind, use the same energy source to heat ... yeah, it goes on.

We're fighting less of a heat battle

But there are indications that running the A/C for hours on end in Phoenix is better than running the heat nonstop in a colder climate, even if it may be inherently more efficient to heat a space than cool it.

For one, there's a thing called the heat differential.

So, say it's 120 degrees outside, and you've got your thermostat set at 80 degrees (that may be a little hot for some of you, but stick with me here). There are 40 degrees difference between the temperature outside and the temperature you want to maintain.

MORE: Phoenix heat is rising, and so is the danger

Now, say it's 30 degrees below zero and you want you keep your house at 65 degrees (again, a little cold, but we're going for extremes in both examples). That's a 95-degree difference.

Regardless of your fuel source or its cost, it's going to take more energy to maintain a constant temperature with a 95-degree temperature difference than a 40-degree one.

"Whether you’re heating or cooling, you’re always fighting heat gain or heat loss," said Nathan Morey, a product-development manager for SRP, one of Phoenix's primary energy providers.

Arizona uses a lot and still ranks low

In other words, the larger the temperature differential, the more heat gain or loss you must fight. Phoenix has a leg up because it has a smaller differential. Our average temperature is 75 degrees – almost the temperature you'd want to keep your house – compared to 51 degrees in a cold-weather place like Boston.

You can see this play out in data from the U.S. Energy Information Administration. A report using 2009 data found that while Arizona uses four times as much energy to cool homes than the national average, our total energy use per home is 26 percent below the national average.

In other words, yes, we use a lot of energy to cool our homes. But we use so much less to heat them the rest of the year that it makes up for it.

You also can see this in the EIA's state energy rankings, where hot-weather states generally use less per capita than cold-weather states. Arizona ranks 45th.

Of course, even this is an imperfect comparison. Texas and Louisiana are outliers because they use a lot of energy in oil production, while energy-efficient Massachusetts uses far less energy per capita than its neighbors.

"All things being equal, I’d rather be cooling than heating," says Martin Pasqualetti, a sustainability professor at Arizona State University. "I'd rather live here than there based on energy alone."

Reach Allhands at joanna.allhands@arizonarepublic.com.

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