Nighttime Temperatures and Air Conditioning

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A new report by Arizona State University Researchers reveals that nighttime temperatures in the Phoenix area actually increase one to two degrees because of the excess heat being released by air conditioners. Francisco Salamanca, a post-doctoral research scientist at Arizona State University’s School of Mathematical and Statistical Sciences, and ASU mathematics professor Alex Mahalov will discuss the report.

Ted Simons: A new report by ASU researchers shows that nighttime temperatures in the Phoenix area increase one to two degrees because of excess heat being released by air conditioners. Joining us now to talk about their report, ASU mathematics professor Alex Mahalov, and Francisco Salamanca, post-doctoral research scientist at ASU's school of mathemetical and statistical sciences. Good to have you both here. Are we talking about air conditioning units contributing to global warming?

Alex Mahalov: Yes. Air conditioning is sort of like refrigerator. So you cool your house, but then you have waste heat, and it increases the heat island by one degrees.

Ted Simons: And anyone who stood by the air conditioning unit outside or if they've been on the roof when it's on, they know warm air does come out. This influences more at night than the day? Why is that?

Francisco Salamanca: because during the day the energy coming from the sun dominates, so even though you aren't putting any heat outside, they think the temperature is more. However, at night it's definitely stronger.

Ted Simons: How did you do this research? How was it conducted?

Alex Mahalov: Research was funded by National Science Foundation, and so the model is a meteorological model coupled with building chemistry models. So we take into account everything.

Ted Simons: Ok, and -- But again, it was over a certain period of time, were certain areas focused on? What did you get there?

Alex Mahalov: We used one period in July 2009 just to validate our model. But our research is fundamental and can be applied to Phoenix and other metropolitan areas.

Ted Simons: It sounds like a 10-day period there in 2009. And again, when you went into the research, what were you specifically looking for?

Francisco Salamanca: Well, we were looking for the average in air conditioning temperature in the day time. At the beginning we were not expecting this magnitude, so it was a surprise this significant affect-- Really our focus was the effect of air conditioning on the temperature.

Ted Simons: It's basically like the urban heat isle in effect as well. You've got more air conditioning units together, more of an effect I would imagine.

Francisco Salamanca: Yes. The air conditioning contributes to the heat island. So in July the head island in Phoenix it's around 10, 12 degrees. So two degrees are responsible from air conditioners.

Ted Simons: As far as just doing the study in the first place, whose idea was this? Who said, let's find out? Everyone knows there is waste heat coming out of their air conditioning units. Whoever thought to say, let's see if this is affecting the atmosphere?

Alex Mahalov: Francisco.

Ted Simons: Oh Francisco does, all right. What made you go out there and look for this?

Francisco Salamanca: Some years ago during my disease, I was looking, trying to understand the effect, so in the past I applied it to Madrid, so why not in Phoenix?

Ted Simons: Yeah, and you said were you surprised by the findings.

Francisco Salamanca: Yes, I was waiting for a smaller effect. Phoenix is a big city, temperature is very high in the summer, so the effect is stronger.

Ted Simons: And you also now look at electricity use as well and how did that factor in here?

Alex Mahalov: Yes, actually one or two degree is a lot, one or two degrees matters. I brought with me my air conditioning bill, and I can compare June and July, so in July average temperature was one degree higher and my bill is $30 more. So now if we have 1 million households in the state of Arizona, multiplied by 30, $30 million per month. It wastes heat.

Ted Simons: It wastse heat. But what -- It seems like it's almost a closed loop here in the sense that it's getting warmer, I need to cool down. I'm cooling down, I'm making it warmer. It just goes round and round.

Alex Mahalov: Exactly. It's a negative feedback loop, but can actually we can turn it around.

Ted Simons: How can we turn it around?
Alex Mahalov: It's called waste heat. When you have waste, what you do? You recycle. One solution is actually, instead use this, capture this heat from air conditioning, and run it through water heater. So if you do it, so you get hot water, and then you actually reduce your electric bill. So it's a win-win situation. First you don't contribute to the heat island, and then you reduce your water heater bill.

Ted Simons: Is that the kind of solution you're looking for when you start looking at this kind of thing?

Francisco Salamanca: No, I was not thinking in this solution, just I was thinking to quantify the effect of the air conditioning, and that's it.

Ted Simons: So nothing more, but it seems to make sense doesn't it?

Francisco Salamanca: Yeah, it made sense, the important point we can do is if our indoor temperature is working at 75, just increase to 80, for example, and we save energy, we reduce the impact, and our bill will be lower.

Ted Simons: Yeah, so are there other things, besides perhaps water heaters, are there other things this excess waste heat can be used for?

Alex Mahalov: Well cooking, and maybe some others - well think about it.

Ted Simons: You have to find a way to capture that and bring it back into the house.

Alex Mahalov: Right. But it's probably not very difficult. But if you think about the magnitude of this problem, the magnitude of the solution, right as I said it's like, 300-250 million dollars. You know, you're moving this waste heat for good purposes and plus on top of that, say on your electric bill on water heater right. So it's a very significant.

Ted Simons: If it's that significant, are you working with anyone now to say, hey, I got something significant here. Let's work on -- Let's find a way to capture this stuff and use it again.

Alex Mahalov: Well we are working, but we'd like to work more, hopefully after your Arizona Horizon we'll have some phone calls and we'll redouble our efforts.

Ted Simons: We'll do copyright discussion after the show there. But yeah I understand, it makes sense, and again I wonder if that closed loop idea was something that you thought about as well when you started on this research, when you embarked on this research. Or was it basically a research project saying, if X, then Y?

Francisco Salamanca: People underestimated nighttime temperatures in the cities, so the study is important for two points. One, we can quantify if the effect of the air conditioner. Another point is we are improving the weather forecasting models. When we compare the temperature you can consider the heat, that is much better than if you don't consider this heat.

Ted Simons: Last question, what do we take from this study?

Alex Mahalov: It's to find sustainable solution. We identify problem, and then Arizona is growing, and so this kind of problems we need to transform this into solutions. Positive feedback loop, always positive feedback loop. I think the future is very bright, because we could use energy for good purposes.

Ted Simons: All right. Well, it's an interesting study. I think anyone who stood next to one of those blowers would think that's warm temperature, and you're saying it does make a difference. Thank you for your research and thank you for joining us on the show.

Alex Mahalov: Thank you.

Ted Simons: Tomorrow on "Arizona Horizon," we'll hear from the attorney representing a former Tom Horne aide who alleges that Horne broke campaign laws.

Ted Simons: And find out about a survey on young people's attitudes toward voting. That's Tuesday evening at 5:30 and 10:00 on "Arizona Horizon." Reminder,, that's where you can find us on the web, you can see past shows and you can see what we have planned in the future, That is it for now, I'm Ted Simons. Thank you so much for joining us and you have a great night.

Francisco Salamanca:Post-Doctoral Research Scientist, Arizona State University's School of Mathematical and Statistical Sciences; Alex Mahalov:Mathematics Professor, Arizona State University's School of Mathematical and Statistical Sciences;

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