David+Feeley+张晓敏

Who gets to plan the cities of the future？ You do！ It may all start with the roof over your head. Roofs of future cities will look and feel cooler. "Green" plant covered and "Cool" white or pastel1） roofs have long been popular in Europe， the Middle East， and Canada. Now roofs that look more like meadows than asphalted2） streets， plus those that paint a pretty pastel picture， are becoming part of the "greening" of America.

未来的城市由谁来着手规划？由你来！这一切或许都可以从你头上的屋顶开始。未来城市的屋顶看上去和感觉上都将会更凉爽。在欧洲、中东和加拿大，一直都很流行将屋顶种满“绿色”植物并且刷成“凉爽的”白色或是柔和的色彩。现在，那些看上去更像草坪而不是沥青马路的屋顶，还有那些画着一幅美丽的彩色图画的屋顶正成为美国“绿化”的一部分。

Jackman School

Students， teachers and parents at Jackman Avenue Public School in Toronto， Canada， had a problem： heat. They knew air conditioners weren't an eco-friendly solution because they waste energy and just heat up the neighborhood. So， looking to the future， they used ultraviolet3） （UV） film4） and solar blinds for their windows， and added ceiling fans and shade trees. They also put a Green Roof on the school.

The Heat Island Effect

Cities full of buildings with Jackman School's problem are in big trouble！ The United States Environmental Protection Agency （EPA） says that due to the "Heat Island Effect"， cities and suburbs are 2 to 10 degrees Fahrenheit （F） hotter than nearby country areas. Tall buildings with flat roofs and narrow streets trap heat from cars， factories and air conditioners. This adds to global warming. In cold， northern locations， cities may stay a little warmer in winter， but most of the year they need more energy to get cool.

Cities have other problems too. They have increasing levels of pollution， which make people sick， and rainwater from roofs washes through city streets without becoming part of our needed watershed5）. How can the 3.3 billion people now living in our cities survive in the future as temperatures climb higher due to global warming？ Bob Fittro， of DesignandBuildwithMetal.com， says green roofs—those with a plant covering—can certainly help. "Where roofs are flat， plant covered systems have been shown to keep buildings cooler inside， and as an added benefit they turn roofs into enjoyable park-like spaces，" he says.

Green Roof Pros and Cons

On a summer day， the temperature of a roof can reach 140 to 190 degrees F. Think about it： an egg fries in a 158-degree F pan！ Covered with grass to absorb sunlight， the temperature of that same roof wouldn't rise above 77 degrees F. After a couple of years， plant roots get so dense that they act like a warm coat， lowering heating costs in winter， even when that coat is more brown than green.

Balmori Associates， an urban landscape design firm based in New York City， built a 35，000-squarefoot green roof atop Silvercup Studios in Queens， New York. The firm found a 30～50 percent reduction of energy use for climate control for the building in the summer and nearly a 50～100 percent reduction in spring and fall.

You can breathe deeply with a green roof， too， because they clean the air by catching particles of pollution， and use carbon dioxide to make more oxygen. They also absorb traffic， machinery and airplane noise. So future cities with Green Roofs will be cooler， cleaner and quieter.

Storm water is stored by a green roof and its plants return water to the air. Extra water is cleaned and cooled by plants before it leaves the roof. Jackman student research showed their green roof had about 75 percent less runoff water than before adding a green roof.

Balmori Associates planned a green roof for an environmentally progressive residential tower in New York City， called The Solaire， which stores rainwater not absorbed by its plants， along with the building's grey water6）， in a basement cistern7） where it is filtered and reused to irrigate8） nearby parks as needed.

Owners of the Fairmount Waterfront Hotel in Vancouver， Canada， save about $30，000 a year by using the herbs and vegetables growing on the building's roof.

Green roofs also are healthy， safe places to relax and play in a crowded city. Some local plants and animals even find a home there.

Making It Green

（and Yellow， Red and Brown）

A rooftop is a tough place to live. There are high winds， extreme hot and cold temperatures， and usually very little water. For its green roof， the Jackman team chose local plants with brightly colored flowers and shallow roots. Bergamot， yarrow， asters， geraniums， daisies， coneflowers and four kinds of sedum9） are included. Their "green" roof is actually shades10） of yellow， red， purple and brown. The Silvercup Studios' green roof has 20 different sedum varieties growing in a pattern of green strips and blocks that bloom in yellows， reds and pinks from spring to fall.

Tomorrow

Many groups have grand plans for future cities. One is a project by Balmori Associates called Shanghai Bund in China， where they propose to create a 20-meter green zone connecting the city to Huangpu River. With engineered islands to clean and filter water and generate energy， Shanghai Bund will be a zero-waste11） landscape. You'll see plenty of green roofs there.

The best choices will improve our lives and the cities we live in by respecting each other and the planet we so depend upon.

杰克曼学校的故事

加拿大多伦多杰克曼大街公立学校的学生、老师和家长们之前碰到过一个难题：炎热。他们知道开空调并不是个环保的方法，因为空调浪费能源，只会使居住区变得更热。所以，放眼未来，他们给窗户贴上了紫外线薄膜，装上了遮阳百叶窗，还安上了吊扇，栽了遮阴树。他们还为学校建造了绿色屋顶。

热岛效应

不少城市满是面临杰克曼学校这种难题的建筑，大麻烦也由此而来！美国环境保护署宣布，由于“热岛效应”，城市和郊区的温度会比邻近的乡村地区高出2～10华氏度（编注：1华氏度约等于17.2摄氏度）。平顶高楼和狭窄的街道令汽车、工厂以及空调散发的热量无法外散，而这又加剧了全球变暖。美国那些位于北部寒冷地区的城市在冬天也许仍能稍微暖和一些，但是一年中的大部分时候它们需要更多能源来降温。

城市还面临着其他问题。城市里有越来越严重的致人生病的污染，而且顺着楼顶流下来的雨水从城市的街道冲刷而过，却没有成为我们所需要的集水区的一部分。……