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ТОП 10 на сайтеПриготовление дезинфицирующих растворов различной концентрации
Техника нижней прямой подачи мяча.
Франко-прусская война (причины и последствия)
Организация работы процедурного кабинета
Смысловое и механическое запоминание, их место и роль в усвоении знаний
Коммуникативные барьеры и пути их преодоления
Обработка изделий медицинского назначения многократного применения
Образцы текста публицистического стиля
Четыре типа изменения баланса
Задачи с ответами для Всероссийской олимпиады по праву
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ЗНАЕТЕ ЛИ ВЫ?
Влияние общества на человека
Приготовление дезинфицирующих растворов различной концентрации
Практические работы по географии для 6 класса
Организация работы процедурного кабинета
Изменения в неживой природе осенью
Уборка процедурного кабинета
Сольфеджио. Все правила по сольфеджио
Балочные системы. Определение реакций опор и моментов защемления
Reducing environmental impact
Green building practices aim to reduce the environmental impact of buildings, so the very first rule is: the greenest building is the building that doesn't get built. New construction almost always degrades a building site, so not building is preferable to building. The second rule is: every building should be as small as possible. The third rule is: do not contribute to sprawl (the tendency for cities to spread out in a disordered fashion). No matter how much grass you put on your roof, no matter how many energy-efficient windows, etc., you use, if you contribute to sprawl, you've just defeated your purpose. Urban infill sites are preferable to suburban "greenfield" sites.
Buildings account for a large amount of land. According to the National Resources Inventory, approximately 107 million acres (430,000 km2) of land in the United States are developed. The International Energy Agency released a publication that estimated that existing buildings are responsible for more than 40% of the world’s total primary energy consumption and for 24% of global carbon dioxide emissions.
to safeguard – сохранить
eco-friendly – экологически-чистый
sustainable building – устойчивое строительство
environmentally responsible – ответственный за окружающую среду
resource-efficient – ресурсосберегающий
siting – подбор места для строительства
operation - эксплуатация
maintenance – содержание
to complement - дополнить
occupant – житель
contribute – вкладывать деньги
to sprawl – расшириться
in a disordered fashion – в беспорядочной форме
The term “central heating” applied to the heating of domestic and other buildings indicates that the whole of a building is heated from a central source, usually an independent boiler, fired by solid fuel, gas, electricity or fuel oil.
In general, a heating system should be designed so that the water will circulate by gravity. In some installations, circumstances are such that a pump or accelerator must be used to achieve a satisfactory circulation. This should be avoided if possible.
When designing a heating system for a large building, it is usual – in the interests of economy and to ensure efficient heating – to first calculate how much heat will be needed to maintain the building at the desired temperature. Then the size of the boiler and the amount of pipe and radiator heating surface required to give out this heat will be estimated. For small systems, “rules-of-thumb” methods and past experience are generally a sufficient guide.
A steam, or a hot water heating plant consists essentially of the radiators, the boiler and the system of piping connecting the former with the latter. Steam or hot water from the boiler is circulated through the piping and radiators: in these the steam condenses giving up its latent heat and the water given up some of its heat, thus warming the rooms. In the usual hot water installation, the boiler, pipes and radiators are kept full of water at all times, an expansion tank being provided to compensate for the increase in volume of water when heated and to prevent explosions in case of generation of too much steam.
Boilers. The boiler is usually placed at the lowest available point in the building, having regard at the same time to the convenience of stoking and delivery of fuel.
The boiler may be one of a number of types. It may be solid one-piece casting, rectangular in form; it may be sectional; or it may be conical in shape and wrought or cast iron. For smaller systems, the first and last-named types are both cheap and suitable. The sectional boiler has the advantage of the possibility of added sections should more heat be needed subsequent to initial installation.
System of piping. For steam heating the systems of piping usually employed are the ordinary one-pipe system and two-pipe system. In the former, but one connection is made to each radiator, this connection serving both as inlet for the steam and an outlet for the water of condensation. In the latter, there is a supply pipe and a return pipe for each radiator. The two-pipe system is expensive, and hot used generally in steam heating except for indirect radiators which must always have two connections in order to function properly.
In hot-water heating, although one-pipe systems may be used, it is considered the best practice to have a supply pipe and a return pipe for each *****les and tables for computing the size of pipe for both system and hot water heating will be found in handbooks.
In selecting a heating plant for residences there must be considered the size, the type of building, the climate and the first cost of operation.
Water and Air Pollution Problems
Water and air pollution are the two main factors that destroy the environment in big cities. Paris has no industry, so the Seine is not polluted by industrial effluents but by sewer waters. However, this problem is being solved by building pollution control stations in a Paris suburb. The sewage is channeled into them and cleansed before it goes into the Seine. When visiting these installations, one can often see how pure water the processed water is – the engineers who work there drink it quite cheerfully.
Water is purified by mechanical and biological methods. The purified water is treated with chlorine and released into the rivers, whence it enters the water supply systems where it undergoes further and finer treatment.
Air is mainly polluted by heating systems and cars. When you look at a modern city from a hill top you get the impression of vapour (smog) lingering over the city especially when there are no winds which can air the city. However, when there is no wind they have smog. As regards heating, gas is used rather than coal for last years. The poisoned air is the most modern quarters of the city.
District heating is an effective method. Several heat-and-power plants generate steam, which is piped underground all round the city.
As for cars you know, of course, how heavy traffic is in big cities. The slower the traffic, the more exhaust fumes are. This problem will be solved in the near future.
The acuteness of the problem depends on how well the country is developed and on the number of the cars. Many of these problems are international in nature.
Water and Water Supply
Centralized water supply dates back to 2500 BC. Ancient Egypt had complex engineering structures for the purpose. Yet to this day the percentage of the population enjoying centralized water supply on the African continent and in Asia, too, is very low.
In our country, at the time of the Revolution of 1917, only one third of the towns had running water laid on, and, then, as a rule, only in the central part of the town. In the pre-war period of industrial development running water reached millions of flats all over the country. Water supply of the systems are practically all in the western and central parts of European Russia, were destroyed during the war and had to be built anew.
Fresh water shortage was first mentioned soon after the end of the Second World War. The first to feel the stint was Europe. The problem came to many as a complete surprise, something in the nature of an unexpected “catastrophe”. This catastrophe, however, should have been foreseen, for it follows logically from the development of human life on our planet and of Man’s industrial activity.
In the absence of centralized water supply, a man can do with about 25 litres of water a day for his various personal needs. But in the modern city water consumption per person is much higher. An average of 300 to 500 litres of water is spent daily on household and sanitary needs per one inhabitant of a modern city. You can see this vastly exceeds the necessary minimum of 25 litres. Why the discrepancy (difference)? Not because people leave their taps open. Because water is so abundant nobody thinks twice about taking a shower, or a bath, using the washing machine, washing the car, etc. The volume of water consumption is indicative not only of the efficiency of the water supply but also of the population’s living standards.
One need in water is growing. Simultaneously, the globe’s population is growing. In the past century the consumption of water by the world’s largest cities, such as Paris, London, Berlin and Moscow, has grown 80 to 100 times. During the famous heat wave of 1972 Moscow “drank” almost 5,000,000 cubic metres of water a day. This staggering figure seems to confirm the immediacy of the water dearth problem. In actual fact, however, the problem consists not so much in where to get pure water but in how to deliver it to where people need it.
Water Resources of the USA
The USA is one of the first countries whose developing economy has met with a shortage of pure fresh water. Such conflicting situations have been caused by the exceptionally rapid growth of water consumption and by the constancy of the size of river runoff. The water crisis began to show at the beginning of the 60s. It was then when the gigantic projects were born to transport fresh water from Canada and Alaska to the main territory of the USA. At the end of 60s it became evident that the problem could not be solved by purifying utilized water.
By spending large sums of money on developing gigantic desalination plants it became clear that by channeling the runoff from the neighbouring territories and from the ocean an increase in the volume of polluted water would be brought about, which even at present overfills the rivers and lakes of the country.
It is the runoff which can be used without a full regulation of rivers by hydrotechnical installations. It is possible by recycling the same volume of water, which claims great requirements to the quality of their purification.
The main increase in water consumption takes place in that sphere of national economy, where water is necessary principally for cooling purposes – in industry, especially in heat-power engineering.
How can water losses be replenished? It is necessary to note the evergrowing consumption of ground water. The removal of considerably greater volumes of ground water that are taken at present will not diminish their total storage for a long time. Water supply at the expense of ground water is also convenient to satisfy the every day necessities of the population.
Other reserves that can be used are the water of the ocean. A wide substitution of fresh water for salt water for cooling purposes is assumed, mainly in heat-power engineering.
Over one quarter of the whole consumption of water will become possible due to the use of seawater. As concerning the abovementioned projects according to which fresh water is to be transported from Canada and Alaska and the entailed possibility to use the great reserves of hydropower of the western part of the continent, they have been cancelled.
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