Environment

Sometimes hot growth is not a good thing: Study to explore how to cut cooling expenses

November 7, 2005

The definition of an "urban heat island" in Indianapolis would be incomplete if limited to, say, the hot air emanating from the Statehouse during the session.

To Qihao Weng, an urban heat island refers to how an entire city remains up to 10 degrees warmer than the surrounding countryside. The Indiana State University associate professor of geography has launched a study to learn just how Indianapolis' concrete jungle heats up in warm-weather months and by how much.

His study funded by the National Science Foundation ultimately will provide a template for developing solutions to reducing heat buildup that in the summer diminishes the city's livability and drives up air-conditioning costs for businesses and homeowners.

Indirectly, excess heat harms the environment through the burning of more coal at Indiana's electric generating plants. Excessive heat also contributes to any number of health ailments.

Weng's team has already been looking at infrared heat images of Indianapolis that were captured by satellites. In them, the roofs of individual downtown buildings show up in different colors, depending on temperature. Dark-colored roofs tend to be hottest, lighter colors coolest because they reflect sunlight.

As part of building a profile of the city's heat levels, researchers will look at how, say, a parking lot contributes to heat. Conversely, to what degree does a forested park offset heat?

"We're looking at an interesting mosaic here," Weng said.

Indianapolis lags behind larger cities as far as giving serious consideration to the heat island effect. And the city's trees and cornfields increasingly are being mowed down for shopping centers and vinyl villages-the unflattering term for cheap, high-density housing developments spreading like wildfire in Marion and surrounding counties.

Although Indianapolis is no Atlanta when it comes to growth, "Indianapolis is expanding very quickly," Weng added.

The "Energy Savings for Heat Island Reduction Strategies in Chicago and Houston" study, published by Lawrence Berkeley National Laboratory in 2002, found that Houston could cut energy costs $82 million by taking steps such as planting more trees and making roof surfaces more reflective.

The study said such measures could cut Chicago's energy costs $30 million annually. That doesn't count the reduction in carbon emissions from power plants.

Weng's research will take three years, in part because it will be painstaking. Researchers even plan to look at to what degree pollution in a river affects temperature.

It turns out this whole heat phenomenon in urban settings is incredibly complicated stuff, as University of Chicago environmental studies professor John E. Frederick can attest. Researchers have spent months scaling the urban canyons of downtown Chicago taking measurements. They noted that even water droplets and particles in the air emit varying levels of heat.

Add to the equation the color not only of roofs but also of a building's vertical surfaces. Those surfaces alone can make a big difference in overnight temperatures in a city, Frederick said.

One solution to the heat problem is planting more trees, said Tim Maloney, executive director of the Hoosier Environmental Council. But a tree preservation plan launched way back in the Mayor Bill Hudnut administration, in the 1980s, has basically gone nowhere in subsequent administrations, environmentalists lament.

Some in city hall feel the research might be worth it. Don Miller, land steward coordinator for Indy Parks and Recreation, said he hopes Weng's research will be available to city planners "who must take into account the complicated interactions between urban land cover and natural surfaces in reducing effects of heat."

The city's relatively developer-friendly planning guidelines have yet to address the heat island issue directly. The city's Indianapolis Regional Center Plan 2020 does encourage "green buildings" that take into account energy efficiency and ecologically sound practices in new land development. It also calls for more landscaping and an increase in the number of trees, especially along riverfronts and thoroughfares.

Of course, methods of reducing heat in the summer can backfire in the winter-when dark-colored buildings and miles of pavement are welcome in raising a city's temperature and helping reduce heating costs.

Maloney said building designers and owners could gain far more in the cold months by making buildings more energy-efficient than by worrying about building colors.
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