我想問....

1. This phenomenon describes urban and suburban temperatures that are 2 to 10°F (1 to 6°C) hotter than nearby rural areas. Elevated temperatures can impact communities by increasing peak energy demand, air conditioning costs, air pollution levels, and heat-related illness and mortality.


2. There are a number of steps that communities can take to lessen the impacts of heat islands. These "heat island reduction strategies" include: installing cool or vegetated green roofs; planting trees and vegetation; and switching to cool paving materials.

The extent to which urban areas can benefit from heat island reduction strategies depends on several factors. Some of these factors, like prevailing weather patterns, geography, and pollution transported from up-wind regions, are largely beyond the influence of local policy.

However, factors such as land-use patterns, materials used in road and building construction, and the coverage of urban trees and vegetation can be directly affected by decision makers. This is where policies and programs to reduce the impacts of heat islands – and achieve related environmental and energy-savings goals – can be most effective.



On a hot, sunny, summer day, traditional roofing materials may reach summertime peak temperatures of up to 190°F (88°C). By comparison, cool roofs only reach peak temperatures of 120°F (49°C).These materials reflect a large portion of the sun's energy. Cool roofs also may have a high thermal emittance
圖片參考：http://www.epa.gov/heatisland/images/dot_blue.gif
, and thus release a large percentage of absorbed heat. This keeps the material cooler and helps to reduce the heat island effect.



Another alternative to traditional roofing materials is a rooftop garden or "green roof." Installed widely in a city, green roofs contribute to heat island reduction by replacing heat-absorbing surfaces with plants, shrubs, and small trees that cool the air through evapotranspiration (or evaporation of water from leaves). Planted rooftops remain significantly cooler than a rooftop constructed from traditional heat-absorbing materials. Further, green roofs reduce summertime air conditioning demand by lowering heat gain to the building.


Increasing the cover of trees and vegetation in a city is a simple and effective way to reduce the urban heat island effect. Trees provide a wide range of other benefits, from increasing property value to reducing storm water runoff.

Shade trees also can make homes and buildings significantly more energy efficient. Scientists estimate that strategically planting trees and vegetation reduces cooling energy consumption by up to 25%. For many, this research comes as no surprise—trees have been used to cool homes for hundreds of years.


3. Mainly it's because the people didn't have enough concern on these problem. They continue to do things which get harm to the nature. For example, turn on the air conditioner, build the tall builiding. Those building construction projects are approved by the government. That shows the government helps to intensify the heat island effect. Without the government support, it's hard to tackle the heat island problem.