In the late 1960s, many people in North America turned their attention to environmental problems, and new steel-and-glass skyscrapers were widely criticized. Ecologists pointed out that a cluster of tall buildings in a city often overburdens public transportation and parking lot capacities.
Skyscrapers are also lavish consumers, and wasters, of electric power. In one recent year, the addition of 17 million square feet of skyscraper office space in New York City raised the peak daily demand for electricity by 120, 000 kilowatts-enough to supply the entire city of Albany, New York, for a day.
Glass-walled skyscrapers can be especially wasteful. The heat loss through a wall of half-inch plate glass is more than ten times that through a typical masonry wall filled with insulation board. To lessen the strain on heating and air-conditioning equipment, builders of skyscrapers have begun to use double-glazed panels of glass, and reflective glasses coated with silver or gold mirror films that reduce glare as well as heat gain. However, mirror-walled skyscrapers raise the temperature of the surrounding air and affect neighboring buildings.
Skyscrapers put a severe strain on a citys sanitation facilities, too. If fully occupied, the two World Trade Center towers in New York City would alone generate 2.25 million gallons of raw sewage each year-as much as a city the size of Stanford, Connecticut , which has a population of more than 109, 000.
九年级英语教案Unit 7(新目标)
北京课改版英语八下《Unit 12 Working at the Vet’s》word教案和练习
北京课改版英语九年《Unit 4 Michael Jordan》word教案和练习
九年级英语教案Unit 12(新目标)
九年级英语教案Review of units 6~10(新目标)
人教版英语八下Unit 2《I’ll help to clean up the city park》学案
北京课改版英语九年《Unit 6 Let’s Learn Chinese》word知识精讲
北京课改版英语八下《Unit 3 The Sports Meet》word教案和练习
九年级英语教案Unit 11(新目标)
九年级英语教案Unit 5(新目标)
九年级英语教学计划
九年级英语教案Unit 15(新目标)
北京课改版英语九年《Unit 1 Smile and Say Hello》word知识精讲
九年级英语教案Unit 14(新目标)
北京课改版英语八下《Unit 1 The Snail and the Rose Tree》word教案和练习
北京课改版英语九年《Unit 17 The Last English Class》word预习导学案
北京课改版英语九年《Unit 12 At the zoo》word知识精讲
九年级英语教案Unit 2(新目标)
北京课改版英语八下《Unit 4 No Smoking》word教案和练习
人教版九年级上册英语全册教案
北京课改版英语九年《Unit 16 An English Camp》word知识精讲
北京课改版英语九年《Unit 8 Grandma to the Rescue》word教案和练习
北京课改版英语九年《Unit 3 Happy Halloween》word知识精讲
北京课改版英语九年《Unit 13 William Shakespeare》word教案和练习
九年级英语教案Unit 9(新目标)
九年级英语教案Unit 8(新目标)
北京课改版英语九年《Unit 11 Let’s Protect The Environment》word知识精讲
九年级英语教案Unit 10(新目标)
北京课改版英语九年《Unit 13 William Shakespeare》word知识精讲
九年级英语教案Review of units 11~15(新目标)
| 不限 |
| 英语教案 |
| 英语课件 |
| 英语试题 |
| 不限 |
| 不限 |
| 上册 |
| 下册 |
| 不限 |