Not only is this condition uncomfortable, but for young children, those with chronic illness, and the elderly, it can be life-threatening as well.
Philadelphia's rowhouses - 500,000 of which date from the 1860s to the 1920s - tend to trap heat and humidity during summer, helping create the heat island.
It's not that the builders didn't know how to help keep these houses cooler. For example, floor plans were designed to permit cross-ventilation, houses had metal roofs to reflect the sun, canvas awnings kept down the amount of sunlight shining into the house, and basement windows could be opened in the evening to help bring in cooler air after the sun went down.
Modern concerns, about security for instance, have made some older measures ineffective. Fears of break-ins have led many homeowners to shut the windows tightly, even when such action turns the house into an oven.
Energy costs are a major issue.
In 2000, low-income residential consumers spent 19 percent of household income on energy, up from 14 percent in 1999. Many moderate-income households face budget pressures that set them back to low-income levels, but they are ineligible for assistance.
"These are the people that make too much money to qualify for government assistance with their utility bills and too little to implement energy- and water-conservation improvements that don't offer quick cash savings in their monthly bill," said Robert Brand, president of Solutions for Progress Inc. of Philadelphia, an advocacy group. "These are the very people least able to pay more than necessary for energy and water use."
Even when people can afford air conditioners or fans to keep cooler, the amount of electricity used can be a drain. The residential sector accounts for 30 percent of energy consumption in the nation and produces 19 percent of greenhouse gases.
