A study of several technological approaches to help counteract the effects of global warming finds that not all technologies are effective in all climates and all communities.
“This is the first time…these approaches have been examined across various climates and geographies,” said 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 “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,” said Georgescu.
The researchers examined how “cool roofs” and “green roofs” painting roofs and planting foliage to reduce the effect of heat, fared across different geographies and climates of the United States.
In order to reduce energy demand during the summer, “cool roofs,” painting a roof white, has been proposed as an effective strategy. However, the researchers found that during winter, the white painted roof increases the cold and requires additional heating to maintain comfort levels. “Green” roofs, that have foliage added for cooling, don’t cool the temperature as much as white roofs, but they also don’t add additional energy demand during the winter.
And in Florida research simulations indicated that deploying cool roofs results in a 2 to 4 millimeter per day reduction in rainfall that results in reduced water supplies and will have a negative effect on the ecosystem.
Georgescu says the goal of the study was 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…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.”
The study was published in Proceedings of the National Academy of Science and was supported by the National Science Foundation under a Water Sustainability and Climate grant.