VOA标准英语2010年-Scholar Hopes to Cool City By Covering

As Hong Kong struggles to build an environmentally friendly city, one professor is studying ways to help cut carbon emissions¹ and lower electricity usage by covering the city's rooftops with plants.

 

Jim Chi Yung, a geography professor at the University of Hong Kong, set up his first green roof in 2006 on top of one of the buildings at the university. He wanted to research how plants and grass covering a roof affect heating and cooling.

Variety of plants

The roof was divided into four parcels: one is bare concrete, and three others are covered with different plants. The first is grass, the second, a perennial² that produces yellow flowers and the third, a shrub³.

"So far I have been able to figure out quite a significant difference between the three vegetation type in terms of ecological⁴ and environmental benefits," Jim said.

Using infrared⁵ sensors⁶ between the plant layer and the roof, Jim found that the planted areas lowered the roof's surface temperature by as much as 26 degrees Celsius⁷.

Bare roofs can reach temperatures as high as 50 degrees on a hot summer day because of all the solar radiation they take in, while planted surfaces stay closer to air temperature. In the winter, Jim found, the planted area helps the roof below stay warmer.

For building owners this means the top floors of a building remain cooler in the summer and warmer in the winter so less money is spent on heating and cooling.

More research

The professor's study is expanding. He has covered the university's library roof with plants, and he is researching what plants can best endure the intense sunlight in Hong Kong, and can grow in a thin layer of soil.

His plan is to develop a lightweight green roof for the city's old neighborhoods. The older buildings in those areas cannot handle a lot of extra weight on their roofs.

Construction and energy experts say many cities in warm climates, such as Hong Kong, never included insulation⁹ and other conservation measures to reduce electricity use.

Green plan

John Herbert is an energy scientist and director of Kelcroft, an environmental consulting company in Hong Kong. He says rapidly developing countries such as China and India can reduce their energy use significantly by avoiding mistakes made in other countries.

"India and developing countries in general should really, instead of just plowing¹⁰ ahead, they should really look at the mistakes the West has made in the building sector¹¹ and not repeat them," Herbert said. "And it's easy not to repeat them because the evidence is here all around us."

The green roofing industry is well established in Europe, Germany in particular, and in Asian countries such as Singapore and Japan. North America is also catching¹² on.

Studies throughout the world show similar results to Professor Jim's. While the temperature reductions vary, all indicate that plants act as added insulation, reducing a building's energy demand. Studies show that can mean savings¹³ of 25 percent in cooling costs.

Pros¹⁴ and cons⁸

Roof gardens also can reduce storm water run-off and help combat the urban heat island effect. That is caused by heat bouncing off concrete and steel, running engines and machinery¹⁵ and pollution. City temperatures can be up to three degrees higher than in rural areas.

Despite the benefits of green roofs demand in Hong Kong remains¹⁶ relatively¹⁷ low. 

People fear that loading roofs with plants will lead to leaks, cracks, mosquitoes and other pests. They also fear the construction cost and maintenance fees.

So far, the push to create green roofs in Hong Kong is a voluntary, non-profit effort that gets little attention.

Will others follow?

Jim says the government needs to do more.

"What I describe as psychological barriers which could be easily overcome by providing people with the right kind of information and knowledge," Jim said. "We should tell the world a compact city can be built in an environmentally friendly as well as sustainable manner."

Jim hopes that the green roof effort in Hong Kong eventually will follow in Singapore's footsteps - with roof gardens producing fresh vegetables and fruit.
 

1 emissions   

排放物( emission的名词复数 )； 散发物（尤指气体）

参考例句：

• Most scientists accept that climate change is linked to carbon emissions. 大多数科学家都相信气候变化与排放的含碳气体有关。
• Dangerous emissions radiate from plutonium. 危险的辐射物从钚放散出来。

2 perennial   

adj.终年的；长久的

参考例句：

• I wonder at her perennial youthfulness.我对她青春常驻感到惊讶。
• There's a perennial shortage of teachers with science qualifications.有理科教学资格的老师一直都很短缺。

3 shrub   

n.灌木，灌木丛

参考例句：

• There is a small evergreen shrub on the hillside.山腰上有一小块常绿灌木丛。
• Moving a shrub is best done in early spring.移植灌木最好是在初春的时候。

4 ecological   

adj.生态的，生态学的

参考例句：

• The region has been declared an ecological disaster zone.这个地区已经宣布为生态灾难区。
• Each animal has its ecological niche.每种动物都有自己的生态位.

5 infrared   

adj./n.红外线(的)

参考例句：

• Infrared is widely used in industry and medical science.红外线广泛应用于工业和医学科学。
• Infrared radiation has wavelengths longer than those of visible light.红外辐射的波长比可见光的波长长。

6 sensors   

n.传感器，灵敏元件( sensor的名词复数 )

参考例句：

• There were more than 2000 sensors here. 这里装有两千多个灵敏元件。 来自《简明英汉词典》
• Significant changes have been noted where sensors were exposed to trichloride. 当传感器暴露在三氯化物中时，有很大变化。 来自辞典例句

7 Celsius   

adj.摄氏温度计的，摄氏的

参考例句：

• The temperature tonight will fall to seven degrees Celsius.今晚气温将下降到七摄氏度。
• The maximum temperature in July may be 36 degrees Celsius.七月份最高温度可能达到36摄氏度。

8 cons   

n.欺骗，骗局( con的名词复数 )v.诈骗，哄骗( con的第三人称单数 )

参考例句：

• The pros and cons cancel out. 正反两种意见抵消。 来自《现代英汉综合大词典》
• We should hear all the pros and cons of the matter before we make a decision. 我们在对这事做出决定之前，应该先听取正反两方面的意见。 来自《简明英汉词典》

9 insulation   

n.隔离；绝缘；隔热

参考例句：

• Please examine the insulation of the electric wires in my house.请检查一下我屋子里电线的绝缘情况。
• It is always difficult to assure good insulation between the electric leads.要保证两个电触头之间有良好的绝缘总是很困难的。

10 plowing   

v.耕( plow的现在分词 )；犁耕；费力穿过

参考例句：

• "There are things more important now than plowing, Sugar. "如今有比耕种更重要的事情要做呀，宝贝儿。 来自飘（部分）
• Since his wife's death, he has been plowing a lonely furrow. 从他妻子死后，他一直过着孤独的生活。 来自辞典例句

11 sector   

n.部门，部分；防御地段，防区；扇形

参考例句：

• The export sector will aid the economic recovery. 出口产业将促进经济复苏。
• The enemy have attacked the British sector.敌人已进攻英国防区。

12 catching   

adj.易传染的，有魅力的，迷人的，接住

参考例句：

• There are those who think eczema is catching.有人就是认为湿疹会传染。
• Enthusiasm is very catching.热情非常富有感染力。

13 savings   

n.存款，储蓄

参考例句：

• I can't afford the vacation,for it would eat up my savings.我度不起假，那样会把我的积蓄用光的。
• By this time he had used up all his savings.到这时，他的存款已全部用完。

14 pros   

abbr.prosecuting 起诉；prosecutor 起诉人；professionals 自由职业者；proscenium （舞台）前部n.赞成的意见( pro的名词复数 )；赞成的理由；抵偿物；交换物

参考例句：

• The pros and cons cancel out. 正反两种意见抵消。 来自《现代英汉综合大词典》
• We should hear all the pros and cons of the matter before we make a decision. 我们在对这事做出决定之前，应该先听取正反两方面的意见。 来自《简明英汉词典》

15 machinery   

n.(总称)机械，机器；机构

参考例句：

• Has the machinery been put up ready for the broadcast?广播器材安装完毕了吗？
• Machinery ought to be well maintained all the time.机器应该随时注意维护。

16 remains   

n.剩余物，残留物；遗体，遗迹

参考例句：

• He ate the remains of food hungrily.他狼吞虎咽地吃剩余的食物。
• The remains of the meal were fed to the dog.残羹剩饭喂狗了。

17 relatively   

adv.比较...地，相对地

参考例句：

• The rabbit is a relatively recent introduction in Australia.兔子是相对较新引入澳大利亚的物种。
• The operation was relatively painless.手术相对来说不痛。