Materials Cement asphalt and steel

In 2000 Londoners consumed 49 million tonnes of materials - 6.7 tonnes per person. Some 27.8 million tonnes were consumed by the construction sector, out of which 26 million tonnes of waste was generated: 15 million by the construction and demolition sectors, 7.9 million by commerce and industry and 3.4 million by households.

Buildings consume some 40 per cent of materials in the global community. And cement is a key component. In 2000 1.56 billion tonnes of Portland cement was manufactured globally. One third of this was produced in China alone.42 And global demand is expected to double within the next 30 years.

Cement is a noxious, or even obnoxious, substance. Each tonne requires about two tonnes of raw material (limestone and shale), consumes about 4 gigajoules of energy in electricity, process heat and transport (the energy equivalent to 131 m3 of natural gas), produces its equivalent weight in CO2, about 3kg of NOx, a mixture of nitrogen monoxide and nitrogen dioxide that contributes to ground-level smog, and about 0.4 kg of PM10, an airborne particulate matter that is harmful to the respiratory tract when inhaled. Cement manufacturing accounts for approximately 7-8 per cent of CO2 globally. Yet twice as much concrete is used in construction around the world than the total of all other building materials, including wood, steel, plastic and aluminium.43 The annual global production of concrete is about 5 billion cubic yards, which is the equivalent of a massive block 1000m long, 1000m wide and 3824m high, a bit higher than Mount Fuji in Japan (3776m).

More than 65,000 square miles of land have been paved in the lower 48 states to accommodate America's 214 million cars; there are 3.9 million miles of roads, enough to circle the Earth at the equator 157 times, in that area alone.44 This amounts to 2.5 per cent of the total land surface - an area more than the size of Georgia, far, far more if you consider car parks and other areas. For every five cars added to the US fleet, an area the size of a football field is covered with asphalt. Close to half of the land area in most US cities goes to providing roads, highways and parking lots for automobiles, close to two-thirds in the case of Los Angeles. Not many cities calculate their asphalt, but Munich, one of the more environmental cities in Europe, has only 4 per cent pavement, 15 per cent asphalt and 16 per cent built area, against 59 per cent vegetation and 6 per cent bare soils.45 Of London's 175,000 hectare area, 62 per cent is urban - buildings, asphalt, and pavement - with 30 per cent of London's area dedicated to parkland.46 Metropolitan Tokyo is 82 per cent covered with asphalt or concrete.47 An area the size of Leicestershire is now taken up by roads in the UK, with an additional fifth as much land given over to parking. 'Once paved, land is not easily reclaimed,' as environmentalist Rupert Cutler once noted. 'Asphalt is the land's last crop.'48

In 1973 the tallest building in the US opened its doors. At 1454 feet tall (110 storeys), the Sears Tower took three years to build at a cost of more than US$150 million. From the Skydeck, on a clear day, you can see four states - Illinois, Indiana, Wisconsin and Michigan. The building contains enough steel to build 50,000 cars, enough telephone wiring to wrap around the world 1.75 times, enough concrete to build an eight-lane, five-mile-long highway; it contains more than 43,000 miles of telephone cable, 2000 miles of electrical wire, 25,000 miles of plumbing and stairways totalling 2232 steps.49 It took 36,910 tonnes of steel to build the Petronas Towers. The Empire State Building contains 60,000 tonnes of steel - 4500 elephant equivalents - and 10 million bricks.50 A three-bedroom detached house requires about 10,000 facing bricks. Total brick production in UK is 2.8 billion a year, which if lined up end to end would reach to the moon and back.51

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