Research reveals effectiveness of urban heat-reducing technologies


February 10, 2014

Life in a warming world is going to require human ingenuity to adapt to the new realities of Earth. Greenhouse-gas-induced warming and megapolitan expansion are both significant drivers of our warming planet. Researchers are now assessing adaptation technologies that could help us acclimate to these changing realities.

But how well these adaptation technologies – such as cool roofs, green roofs and hybrids of the two – perform year-round, and how this performance varies with place remain uncertain. aerial view of a suburban Phoenix neighborhood Download Full Image

Now a team of researchers, led by Matei Georgescu, an assistant professor in Arizona State University's School of Geographical Sciences and Urban Planning and a senior sustainability scientist in the Global Institute of Sustainability, has begun exploring the relative effectiveness of some of the most common adaptation technologies aimed at reducing warming from urban expansion.

The work showed that end-of-century urban expansion within the United States alone, separate from greenhouse-gas-induced climate change, can raise near surface temperatures by up to 3 degrees Celsius (nearly 6 degrees Fahrenheit) for some megapolitan areas. Results of the new study indicate that the performance of urban adaptation technologies can counteract this increase in temperature, but also varies seasonally and is geographically dependent.

In the paper, “Urban adaptation can roll back warming of emerging megapolitan regions,” published in the online Early Edition of the Proceedings of the National Academy of Sciences, Georgescu, Philip Morefield, Britta Bierwagen and Christopher Weaver – all of the U.S. Environmental Protection Agency – examined how these technologies fare across different geographies and climates of the United States (http://www.pnas.org/content/early/2014/02/04/1322280111.abstract).

“This is the first time all of these approaches have been examined across various climates and geographies,” said Georgescu. “We looked at each adaptation strategy and their impacts across all seasons, and we quantified consequences that extend to hydrology (rainfall), climate and energy. We found geography matters,” he said.

Specifically, what works in California’s Central Valley, such as cool roofs, does not necessarily provide the same benefits to other regions of the country, like Florida, Georgescu explained. Assessing consequences that extend beyond near surface temperatures, such as rainfall and energy demand, reveals important tradeoffs that are oftentimes unaccounted for.

Cool roofs are a good example. In an effort to reflect incoming solar radiation, and therefore cool buildings and lessen energy demand during summer, painting one’s roof white has been proposed as an effective strategy. Cool roofs have been found to be particularly effective for certain areas during summertime.

However, during winter, these same urban adaptation strategies, when deployed in northerly locations, further cool the environment, and consequently require additional heating to maintain comfort levels. This is an important seasonal contrast between cool roofs (i.e. highly reflective) and green roofs (i.e. highly transpiring). While green roofs do not cool the environment as much during summer, they also do not compromise summertime energy savings with additional energy demand during winter.

“The energy savings gained during the summer season, for some regions, is nearly entirely lost during the winter season,” Georgescu said.

In Florida, and to a lesser extent southwestern states, there is a very different effect caused by cool roofs.

“In Florida, our simulations indicate a significant reduction in precipitation," he said. "The deployment of cool roofs results in a 2 to 4 millimeter per day reduction in rainfall, a considerable amount (nearly 50 percent) that will have implications for water availability, reduced stream flow and negative consequences for ecosystems. For Florida, cool roofs may not be the optimal way to battle the urban heat island because of these unintended consequences.”

Georgescu said the researchers did not intend to rate urban adaptation technologies as much as to shed light on each technology’s advantages and disadvantages.

“We simply wanted to get all of the technologies on a level playing field and draw out the issues associated with each one, across place and across time.”

Overall, the researchers suggest that judicious planning and design choices should be considered in trying to counteract rising temperatures caused by urban sprawl and greenhouse gases. They add that “urban-induced climate change depends on specific geographic factors that must be assessed when choosing optimal approaches, as opposed to one-size-fits-all solutions.”

Including all expansion scenarios, adaptation strategies and ensemble members, nearly 150 years of regional climate modeling experiments encompassing the continental United States were carried out on ASU's Advanced Computing Center (A2C2).

This research was supported by the National Science Foundation under a Water Sustainability and Climate grant with Georgescu as principal investigator.

Associate Director, Media Relations & Strategic Communications

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Valentine's Day tips to keep your relationship healthy


February 10, 2014

Ah, Valentine’s Day – a time for love and sweet times spent with your significant other. 

If only it were so easy. Romance can be a balancing act, especially if you live with your partner.  Download Full Image

Jess Alberts, Arizona State University President’s Professor in the Hugh Downs School of Human Communication, has spent recent years researching conflict in personal and professional relationships, including marital conflict, the division of domestic labor and couples’ daily interaction.

To make your relationship with your partner work better, Alberts shares these recommendations for managing conflict: 

• Agree with your partner to never do any name calling, ever. “It wounds, and it wounds deeply,” Alberts said. 

• Look at how you attribute blame or how you react to something your partner does or doesn’t do. How you interpret your partner’s behavior has a significant impact on the reason why you are angry. “We don’t respond to what people do. We respond to the reason that we think they did the behavior,” Alberts said.

• If you have a problem with your significant other’s behavior, ask them about their perspective or why they thought their actions were a good idea. The reasons behind what they did may surprise you. Sometimes people are exhausted and not thinking straight. Or, they may think that you would do the same thing in their situation. Or, they may not have been thinking about you when they made their decision. “People usually have reasons for what they do,” Alberts said. 

• Be positive. “I tell students that we fall in love with our reflection in our lover’s eyes. This means that part of the reason we love someone else is how they see us and make us feel. It really helps to have that positive attitude when things are going well, and especially when you fight,” she said. 

• Don’t use your relationship as a source of power. Don’t try to control your partner by telling them what they can and cannot do. “Using your relationship as a source of power doesn’t work very well,” she said. “An argument shouldn’t be about winning. It should be about solving a problem. No one is happy in a relationship where they feel like they have no control and they lose all of the time.” 

• Negotiate household tasks and realize that your significant other may have a lower threshold for mess than you do. Things that one person may not even notice can drive another person nuts. Talk about the division of labor in the household and how you’ll handle it if you have different thresholds for clutter. 

• Don’t stew in anger. Talk about things before you explode. But, be sure to pick a time to talk that is as good for your partner as it is for you.