Evaluation Essay Essay

The National Basketball Association, popularly Known as the NBA, was established in New York City on June 6, 1946, as the Basketball Association of America and the Chicago Bulls became a member of the NBA after their establishment in 1966. Since becoming the NBA, the basketball played during the playoffs has proven to be far more competetive than that played during the regular season of at least 60 games per team. This was proven beyond doubt when the Chicago Bulls defeated the Brooklyn Nets in the 2013 playoffs after trailing by 14 points with only 3 minutes and forteen seconds of regulation time left. This was quite hard to believe and turned out to be an unexpected reality despite the susceptibility of the Chicago Bulls to injury and the absence of their superstar, Derick Rose. With the emergence of the 2008 number 1 draft pick of the NBA, Derick Rose, drafted by the Chicago Bulls, there was hope for an NBA title for the city of Chicago which has not had any hope since the Michael Jordan era. After the horrible 2012/2013 regular season in which the Bulls suffered a great deal of injuries worst than any other NBA team, the Bulls head into the playoffs still short handed. The first impression about this Bulls’ team is their resilience considering their success into the playoffs despite the injury woes. The first round featured the Bulls and the Nets in what is suppose to be a seven game series with the winner being any team with the first four wins. The two teams meet at the Barclays Center in New York for game 4 of the series with the Bulls leading two games to one. The game appeared to be pretty even within the first three quarters untill the nets blowout to a 14 point lead with exactly 3 minutes and 14 seconds of playtime left on the clock. At this point, no one could see the possibilty of a Bulls win considering the absence of a superb playmaker like their all-star point guard, Derick Rose who used to lead them to numerous comeback wins. Notwithstan ding, the bulls backup point guard, Nate Robinson, who is just 5†² 9†³ tall, Weighing 180 lb popularly reffered to as ‘little Nate’ by most basketball journalists and analysts went to work. He can be reffered to at this point as the savior, but who could have imagined that at a crucial point like this, it will be the backup point guard, who is not ony the smallest player on the bulls roster but also one of the least regarded who will bail them out. With the nets leading by 14 at this point, all hope was lost but the Bulls coach, Tom Thibedeau, was still on his toes with the hope to salvage the situation.  Nate took over, first by hitting a three point basket. The lead was down to 11, but the Nets’ coach was pretty relaxed and still had hope for a victory while little Nate thought otherwise. He made 90% of all the points made by the Bulls from this point on. With the Nets loosing the ball at the other end, the bulls converted at the other end. By the time the short clock was at 1:14, the bulls had made and 8:0 run, and the battle was far from done. This was quite unexpected for many reasons. The basketball played during the playoff is way more competitive such that it is rare to see an 8-0 run at a crucial point such as in this situation. In addition to this, the bulls were very short handed compared to a very health Brooklyn team with promissing reserves as well. It all came down to this; â€Å"Who had the passion, who had the drive† as one of the journlists noted. At this point, even though ‘Little Nate ‘ was the main playmaker for the bulls, all the players stepped up their game. Everyone was alert. The rebounding was up, the defending up, the players seemed unstopable at this point. Still, everyone still doubted a bulls win who were still down by 6 points with 1:14 left on the clock. Notwithstanding, the bulls believed in themselves and kept the pace. With the players doing a great job, there was one man who can be reffered to at this point as the fuel, the coach, Tom Thibedeau. He was sensational, and constantly on his toes and he is regarded as someone who believes in winning with no regards to whoever is on the court, whether they are stars, superstars, rookies or average players. This was the mentality he impacted on the bulls despite the absence of their best player. With 1:11 left, the bulls continue to make their run through Nate. Relative to his performance that night, this little guy appeared very tall and not even Brook Lopez, a very big guy of 7 ft 0 and 275 lb on the opposing team could stop him. Lopez put a huge body on ‘little Nate’ whose intelligence overcame the doggy defence. He continued to nock down shots to everyone’s suprise. â€Å"Big things come in small packages† one of the journalists said in reference to his astounding performance. Both teams were level at the end of the fourth quarter and headed for overtime. This was a turn ing point for both teams. While the nets played well, the bulls were clearly the team with the bigger drive to win. Nothing could be seen to limit the bulls not even age in the case of veteran center Nazr Mohammad, the oldest guy on the bulls roster who came off the bench and hit a huge basket with a great offensive rebound that  solidified the bull’s win in the third overtime. In conclusion, the bulls win over the nets in game 4 of the 2013 NBA playoffs was a thriller and no body could have seen it coming. It is worth noting that, believe and hardwork was the driving force of such an unexpected comeback.

Comparative Religions Essay

Judaism began in Israel, 2000 BCE. Christianity began in the middle east it began about 2000 years ago. Christianity is the religion based on the person and teachings of Jesus of Nazareth, or its beliefs and practices. Judaism is the monotheistic religion of the Jews, based on the laws revealed to Moses and recorded in the Torah. Christianity and Judaism are similar and different in many ways, Both Religions believe in Jesus, they have a lot different beliefs, Both religions have Bibles, Christians has the bible, Jews have The Torah. Both religions believe in Jesus. Both religions believed in him but the Christians believed he would come back and that he was very special, Jews did not think all the same as the Christians. Jews do not believe that Jesus was divine, the Son of God, or the Messiah prophesied in Jewish scriptures. He is seen as a â€Å"false messiah,† someone who claimed the mantle of the Messiah but who ultimately did not meet the requirements laid out in Jewish beliefs. Christians believe that Jesus will come back to Earth to save/protect them. Religions have their agreements and their disagreements. The religions have a lot of different beliefs. They have lists and lists of different beliefs of Christians and Jews. Some of those beliefs are, Judaism says that no human can ever die or atone for the sins of others and sins can only be atoned for by animal sacrifice or prayer and restitution. Whereas Christianity says that Jesus died for the sins of mankind. Judaism says that all humans are born pure, and innocent. Christians say that all humans are born with ‘original sin’. Jews say that no man gets a ‘second coming’ and the Messiah will not need one. Christians say that Jesus will have a ‘second coming’. These are only a few of the many different beliefs. Comparisons of the two religions are they both have books basically â€Å"Bibles†, but there not both called bibles. For Christians it is a Bible for Judaism it is a Torah. They both hold basically the same things, Their beliefs. Now the information in the books are not completely the same. Because of the different beliefs. But the books are used for the same reason so people who follow the religion can worship their religion. Christianity and Judaism are very close religions but yet very different. They are the same because, Both Religions believe in Jesus, Both religions have Bibles, Christians has the bible, Jews have The Torah. They are also very different because they have a lot of different beliefs.

Labor Relations Essay Example | Topics and Well Written Essays - 750 words - 1

Labor Relations - Essay Example Otherwise, if they could not be regarded as such commodities within the free labor market, they (employees) could have been dismissed in a procedural manner where they are informed of their terms of dismissal and if they do not agree with same, they can take legal resolutions. There were numerous forms of exploitation of the Americans especially in line with value of independence and liberty in the fight of the freedom of the unions in the early 1900s. There was poor labor relation and laws, and the employees were under the grace of the employers. Some of the factors that led to these exploited included the wide labor market and the fact that employees in the blue collar jobs were slaves or Africans and this created a disparity in the labor market (Dewhirst and Rausch, 2007). The employees’ voices were irrelevant since the unions were never considered powerful by the then government that saw them as antigovernment movements. Therefore, since the government wanted to depress them, employers took the opportunity to maximize on their returns by offering low wedges and imposing cost control, flexibility, and quality on the products. Additionally, employers made employee to work for longer time without extra payments. There are different form of employment relationship bargains including mandatory, permissive, and illegal bargaining items. The illegal bargaining subjects are usually included in collective agreement and it is usually unenforceable. For instance, if a contract denote that employees are to work three times per week. This does not mean that these employees are to snort cocaine for the rest of the month. Notably, snorting cocaine is an illegal activity (Dewhirst and Rausch, 2007); thus, the company and union are never allowed to involve themselves in such bargains. The permissive bargaining subjects are bargains that

Financial markets Essay Example | Topics and Well Written Essays - 750 words

Financial markets - Essay Example Financial markets form one of the financial systems that perform an important economic function by providing a channel of funds from the savers to the spenders or the borrowers that contribute to the economic efficiency. Savers use less money than the incomes while the borrowers wish to sped use more money than their income, which ensures that borrower who want to investor is able to undertake out an investment despite less income by selling bonds to the savers (Mishkin, 2012). The financial market is closely regulated promoting safety in the fund channeling from the savers to the borrowers encouraging a large number of institutions to the markets because they feel secure increasing efficiency in the financial markets. Consequently, increased security in the financial markets translates to the overall economic efficiency. Additionally, financial markets improve consumers’ well-being because it allows them to schedule and time purchases better, which contribute towards the overall economy efficiency in a country and from a global perspective. i. Capital markets trade long term securities in which the institutions as well as the individuals trade financial securities (Bacha & Mirakhor, 2013). The capital markets ensure that financial resources are equally distributed across Qatar. They include A number of securities are traded in the Qatar’s financial markets including Sukuk or Islamic bonds, shares/common stock, commodities, derivatives, and currencies. Islamic bonds are bonds that are not meant to for conventional interests, but help in the development of innovative assets that comply with Islamic law. Oil and gas are the main commodities in the Qatar’s commodity market. b) Diversified and broad platform of investment: Financial markets such as stock exchange offer a wider investment opportunity that lead to the economic development in Qatar. Various companies offer diversified types of securities; hence,

Campaign Evaluation Essay Example | Topics and Well Written Essays - 3000 words

Campaign Evaluation - Essay Example It incorporates specialized skills and expertise in the practice to incorporate and navigate through media relations and public relations without infringing on the practices of each continuum. Public relations relies on the critical and practical tools of media release, media conference and media kits. Further, these tools also combine with the management skills in advising bout the most preferable course of practice or action to follow. Thus, there is need to understand the role of media relations and public relations accordingly in facilitating the establishment of a successful campaign (Delahaye, 2011, p 18). A successful campaign meets the evaluation criteria that encompass the residual practices from media and public relations as facilitating continuums to the topic of campaign evaluation. Media has the potential to evolve the practice of public relations accordingly to reflect a global strategy that features interactive and symmetrical dialogue that is socially responsible. In modeling the two fields, various theoretical approaches are key to facilitate the processes of campaign strategy development and execution (Delahaye, 2011, p 23). Notably, the initial models that define public relations in this context entail the following. First, is the press agency, which constitutes the publicity of the campaign in the process. The fundamental element of publicity develops in the context of evaluating campaign since; publicity uses persuasion and manipulation in the pursuit to influence the audience towards behaving according to the organization objectives and desires (De Beer & Merrill, 2004, p 43). Thus, the audience in this sense relies on the ability of the media agency to develop strategic message that persuades and manipulates the audience accordingly to incline toward s the message of the press agency. Thus, public relations possessing this fundamental element, media relations

Strategic Management Essay Example | Topics and Well Written Essays - 1250 words - 3

Strategic Management - Essay Example Toyota Motor Corporation Toyota Motor Corporation is a company that is leading globally in manufacturing and sales, in the automobile industry. Its main aim is to make better cars and be able to contribute to the society at large. Toyota Motor Corporations is committed to considering the customer first by manufacturing vehicles that are of high quality and those that are of affordable price (Toyota Motor Corporation, 2009). Toyota Motor Corporations believe in a bigger and brighter automobile future. Their main objective is to try and understand the customers’ needs and be able to provide services and products according to these desires. Therefore, Toyota motor corporations is endeavored to pursue the right way forward, to be able to further their growth and make each stakeholder happy and satisfied(Toyota Motors Corporation, 2009). Internal analysis and SWOT Toyota Motor Corporation is termed as the largest manufacturing company of cars by production and sales in the automobi le industry (Schmitt, 2010). It is also the largest manufacturing company in the US, and it is currently operating under five principles, which include; challenge, Kaizen, GenchiGenbutsu, respect, and teamwork (Toyota way, 2001). Despite all these, the Toyota Corporation is faced with strengths, weaknesses, threats, and tries to create opportunities to better their company, like any other in the world. Some of the strengths in the motor corporation include; being able to develop vehicles through innovative technology, and this has been achieved through putting more emphasis on the technological development, healthy corporate environment in which people are able to work and be taught at the same time. This is generalized as working together (Toyota Motor Corporation, 2009). Another strength, is that of tight integration of its group companies and this has helped them to contribute a lot on the economic growth of the nation, and are able to be the pioneers of the creation of a domesti c automobile industry, they are also able to penetrate through the well-known markets including; (Japan, north America and US) (Toyota Motor Corporation, 2009). Apart from the strengths, Toyota Motor Corporation is experiencing some weaknesses within its industry and these include; criticism over large scale recall in 2005, the company was blamed for producing low quality products that lacked innovations. This criticism encouraged them to focus more on designing more innovative cars so as to cater for the customers’ needs. They have gone ahead to make the latest models of primus and hybrid cars, keeping in mind the customers’ satisfaction (Takahashi, 2010). According to Armstrong and Kotler (2002), to be able to manufacture products that are of high quality with stable prices without putting pressure on the competitors will earn the company, a customer’s loyalty, and this is evident in Toyota Motor Corporation. Toyota Motor Corporation is also faced with the wea kness of foreign importation by the Japanese industry, and the company has strived to conquer this problem by producing low priced products in exchange of high quality products (Toyota Motor Corporation, 2009). Toyota Motor Corporation is also faced with the problem of global inefficiency; this means that it is only offering its brands to Japan and US while other competitors offer their brands globally. Therefore, to be able to curb this problem the Toyota Motor Corpo

Electrolux challenges in the appliance industry Essay

Electrolux challenges in the appliance industry - Essay Example Moreover, reducing the cost always could be an efficient way for the Electrolux’s sustainability, the company has relocated approximate 60% of its manufactures to low cost countries like China, India, and Mexico, and it also has reduced its overall energy consumption. In addition, Electrolux has focused on few issues, such as climate change, sound business practices, responsible sourcing and restructuring (Hill & Jones, 2012). Those new strategies helped Electrolux to gain more customer, saved more asset for more investment, furthermore, the strategies helped company to receive more subsidize from the government, this was a major way helped the company’s sustainability directly. The strengths of Electrolux is that it is a well-established company who has kept their head above water and have emerged a greater threat in the market due to their cost efficiency strategy. Electrolux does encounter weakness in their market, mainly currency risk due to operating in dozens of separate counties. Due to their manufacturing utilizing 20% of raw materials they face a larger manufacturing cost as well (Hill & Jones, 2012). Electrolux’s major threats are their number one competitor Whirlpool, as well as increase in labor costs due to Asian wage rises. However Electrolux does have many opportunities they can capitalize on such as becoming the leading socially responsible company in their market. Also the rise in the middle class population suggests that appliances demands should rise which leads to an increase in sales revenue (see appendix A). To measure the efficiency of Electrolux, it is noticeable that the company is not efficient due to its low operating margin. To fix this problem, Electrolux should consider the economic recession and focus more on the inelastic products such as washers and dryers. Since they are a necessity, consumer will spend money on them regardless of

Strategic Alignment Assignment Example | Topics and Well Written Essays - 500 words

Strategic Alignment - Assignment Example Hong Kong is the heart of for the group with three properties in this city. These include the Landmark, Excelsior, and Mandarin Oriental. These properties have registered a greater performance despite the competition in the hotel segment in Hong Kong. Landmark, Excelsior, and Mandarin Oriental generate 38 percent of the total revenues of the group. Mandarin Oriental performs best and utilizes well the market space in Hong Kong contributing an approximate of 15 US dollars per square meter. The group has witnessed a heavy growth of visitors from the mainland China to Hong Kong. In the year 2011, China attracted about 28 million of visitors to Hong Kong. Mainland China recorded 28,100,129 in 2011 and 22,684,388 in the year 2010 (Group Communication 2). It was 67 percent of the total clients of the Mandarin Oriental. Relaxation for individual Visa Scheme in China to people visiting Hong Kong will benefit Mandarin Oriental in its ambitious project of investing in branded residences. This is the principal value driver, which will support Mandarin Oriental competitive method in the hotel industry in Hong Kong. The competitive method capitalizes on the growth of tourism industry in Hong Kong. Tourism industry contributed to growth of Hong Kong GDP by 15.2 percent. There are projections that GDP in Hong Kong will increase by 2.4 percent in 2012. The rate of visitors’ expenditure is favorable for this future and ambitious project of Mandarin Oriental. In 2011, the visitors’ spending was 6,094 US dollars. This was approximately 21 percent increase of the record of 2007 (Group Communication 1). This consistent growth in tourism expenditure will be an advantageous to Mandarin Oriental in Hong Kong. Currently, the Mandarin Oriental uses creative marketing strategy that lays a lot of emphasis on the strengths of the group. The marketing plan addresses a comprehensive set of factors that influence the marketing for the hotel. Sound

Challenges that Walmart and M&S Face Term Paper

Challenges that Walmart and M&S Face - Term Paper Example Walmart is a multinational corporation of the US that operates a large chain of discounted departmental stores. Sam Walton, the founder of Walmart opened its first store in 1962 with a discounting model of retailing. Walmart has expanded and has its presence globally (Walmart, 2011). Michael Mark and Thomas Spencer jointly opened the Marks and Spencer store in the UK, popularly known as M&S, in 1894. M&S operates several retail shops in the UK and is present in other nations as well (Marks & Spencer plc, 2011). Walmart has been able to grow internationally and operate in several countries. There were various challenges present from the diverse forces of the business environment. However, they have been successful in establishing its brand and its presence all over the world. Similarly, M&S grew big with a lot of challenges and created its brand image globally. Both companies operate globally and are also well-known to be the largest retail chains in the world (North Dakota State Univ ersity, 2003). The success of Walmart was its strategy of business operations. They based the operations on web-based application to support their motto of ‘everyday low pricing’ and enhance the satisfaction level of customers (North Dakota State University, 2003). The low pricing strategy and satisfaction level of customers were the major guiding principles of Walmart for their success. They are still following this concept with their existing products and new innovative ideas as well (North Dakota State University, 2003). The success of M&S was because of the innovative development of their knitwear in the UK market. It led to a significant change in the textile industry of the market. During the nineteenth century the market was dominated by the wholesalers, but in the twentieth century, the retail industry started to rule the market. M&S’s innovative idea of product development made the brand international (Riello, 2003). Both Walmart and M&S have been succes sful in their host country first and then as they grew, they became international by opening different stores at several locations of the world. M&S and Walmart are in a similar industry and operate in the international market. Their global presence has made them face global challenges in recent times. The pressures of the international market upon the two are similar in nature as the overall retail industry faces similar challenges. The chief challenge that both M&S and Walmart are facing is that of customer retention. Retention of the customers both in the domestic and the international market has been the biggest challenge. In recent times, the intense competition for retaining and acquiring customers has become the chief challenge and an important objective of the retailers.

Hooters Of America Essay Example | Topics and Well Written Essays - 1750 words

Hooters Of America - Essay Example (Hooters of America, Franchise Disclosure Document, 2010). Therefore, their beginning can be traced back to 1984 with a different name while their functionality under the name of â€Å"Hooters of America† can be traced back to 1989. â€Å"Hooters of America† is mainly concerned with the business of running Hooters Restaurants. However, it has many affiliates, which run different kinds of businesses under the title of â€Å"Hooters† such as Naturally Fresh, Inc., Super Sports Merchandisers, Inc., Super Sports Marketing, Inc., Hooters National Advertising Fund, Inc., Hooters Magazine, Inc., Hooters Racing, Inc., Hooters Sports News, Inc., Hooters Sports Productions, Inc. and National Golf Association, Inc. (Hooters of America, Franchise Disclosure Document, 2010). There are varieties of eatables served at Hooters Restaurants and there are certain unique characteristics that make Hooters Restaurants different from other dining spots. â€Å"Hooters of America† offers franchises for the institutionalization of its restaurants and its services under the name of â€Å"Hooters of America† (Hooters of America, Franchise Disclosure Document, 2010). It is a public traded company. As far as the expanded business of the company is concerned, â€Å"Hooters of America† is a large networked corporation with many affiliates. Their head office is in Georgia. All the affiliates of the company are also located in Georgia (Hooters of America, Franchise Disclosure Document, 2010). The company has license to operate in the whole United States of America and also outside the States. The company provides franchises for restaurants (Hooters of America, Franchise Disclosure Document, 2010). The franchises of â€Å"Hooters of America† are spread in the whole United States due to which, it can be easily stated that the business network of the company is widely expanded. The company,

Chemistry Life in Daily Life Essay Example for Free

Chemistry Life in Daily Life Essay Introduction: Fluorine has the distinction of being the most reactive of all the elements, with the highest electronegativity value on the periodic table. Because of this, it proved extremely difficult to isolate. Davy first identified it as an element, but was poisoned while trying unsuccessfully to decompose hydrogen fluoride. Two other chemists were also later poisoned in similar attempts, and one of them died as a result. French chemist Edmond Fremy (1814-1894) very nearly succeeded in isolating fluorine, and though he failed to do so, he inspired his student Henri Moissan (1852-1907) to continue the project. One of the problems involved in isolating this highly reactive element was the fact that it tends to attack any container in which it is placed: most metals, for instance, will burst into flames in the presence of fluorine. Like the others before him, Moissan set about to isolate fluorine from hydrogen fluoride by means of electrolysis—the use of an electric current to cause a chemical reaction—but in doing so, he used a platinum-iridium alloy that resisted attacks by fluorine. In 1906, he received the Nobel Prize for his work, and his technique is still used today in modified form. Properties And Uses Of Fluorine: A pale green gas of low density, fluorine can combine with all elements except some of the noble gases. Even water will burn in the presence of this highly reactive substance. Fluorine is also highly toxic, and can cause severe burns on contact, yet it also exists in harmless compounds, primarily in the mineral known as fluorspar, or calcium fluoride. The latter gives off a fluorescent light (fluorescence is the term for a type of light not accompanied by heat), and fluorine was named for the mineral that is one of its principal hosts. Beginning in the 1600s, hydrofluoric acid was used for etching glass, and is still used for that purpose today in the manufacture of products such as light bulbs. The oil industry uses it as a catalyst—a substance that speeds along a chemical reaction—to increase the octane number in gasoline. Fluorine is also used in a polymer commonly known as Teflon, which provides a non-stick surface for frying pans and other cooking-related products. Just as chlorine saw service in World War I, fluorine was enlisted in World War II to create a weapon far more terrifying than poison gas: the atomic bomb. Scientists working on the Manhattan Project, the United States effort to develop the bombs dropped on Japan in 1945, needed large quantities of the uranium-235 isotope. This they obtained in large part by diffusion of the compound uranium hexafluoride, which consists of molecules containing one uranium atom and six fluorine anions. Fluoridation Of Water: Long before World War II, health officials in the United States noticed that communities having high concentration of fluoride in their drinking water tended to suffer a much lower incidence of tooth decay. In some areas the concentration of fluoride in the water supply was high enough that it stained peoples teeth; still, at the turn of the century—an era when dental hygiene as we know it today was still in its infancy—the prevention of tooth decay was an attractive prospect. Perhaps, officials surmised, it would be possible to introduce smaller concentrations of fluoride into community drinking water, with a resulting improvement in overall dental health. After World War II, a number of municipalities around the United States ndertook the fluoridation of their water supplies, using concentrations as low as 1 ppm. Within a few years, fluoridation became a hotly debated topic, with proponents pointing to the potential health benefits and opponents arguing from the standpoint of issues not directly involved in science. It was an invasion of personal liberty, they said, for governments to force citizens to drink water which had been supplemented with a foreign substance. During the 1950s, in fact, fluoridation became associated in some circles with Communism—just another manifestation of a government trying to control its citizens. In later years, ironically, antifluoridation efforts became associated with groups on the political left rather than the right. By then, the argument no longer revolved around the issue of government power; instead the concern was for the health risks involved in introducing a substance lethal in large doses. Fluoride had meanwhile gained application in toothpastes. Colgate took the lead, introducing stannous fluoride in 1955. Three years later, the company launched a memorable advertising campaign with commercials in which a little girl showed her mother a report card from the dentist and announced Look, Ma!  No cavities! Within a few years, virtually all brands of toothpaste used fluoride; however, the use of fluoride in drinking water remained controversial. As late as 1993, in fact, the issue of fluoridation remained heated enough to spawn a study by the U. S. National Research Council. The council found some improvement in dental health, but not as large as had been claimed by early proponents of fluoridation. Furthermore, this improvement could be explained by reference to a number of other factors, including fluoride in toothpastes and a generally heightened awareness of dental health among the U.  S. populace. Chlorofluorocarbons : Another controversial application of fluorine is its use, along with chlorine and carbon, in chlorofluorocarbons. As noted above, CFCs have been used in refrigerants and propellants; another application is as a blowing agent for polyurethane foam. This continued for several decades, but in the 1980s, environmentalists became concerned over depletion of the ozone layer high in Earths atmosphere. Unlike ordinary oxygen (O 2 ), ozone or O 3 is capable of absorbing ultraviolet radiation from the Sun, which would otherwise be harmful to human life. It is believed that CFCs catalyze the conversion of ozone to oxygen, and that this may explain the ozone hole, which is particularly noticeable over the Antarctic in September and October. As a result, a number of countries signed an agreement in 1996 to eliminate the manufacture of halocarbons, or substances containing halogens and carbon. Manufacturers in countries that signed this agreement, known as the Montreal Protocol, have developed CFC substitutes, most notably hydrochlorofluorocarbons (HCFCs), CFC-like compounds also containing hydrogen atoms. The ozone-layer question is far from settled, however. Critics argue that in fact the depletion of the ozone layer over Antarctica is a natural occurrence, which may explain why it only occurs at certain times of year. This may also explain why it happens primarily in Antarctica, far from any place where humans have been using CFCs. (Ozone depletion is far less significant in the Arctic, which is much closer to the population centers of the industrialized world. ) In any case, natural sources, such as volcano eruptions, continue to add halogen compounds to the atmosphere. Introduction: Chlorine is a highly poisonous gas, greenish-yellow in color, with a sharp smell that induces choking in humans. Yet, it can combine with other elements to form compounds safe for human consumption. Most notable among these compounds is salt, which has been used as a food preservative since at least 3000 B. C. Salt, of course, occurs in nature. By contrast, the first chlorine compound made by humans was probably hydrochloric acid, created by dissolving hydrogen chloride gas in water. The first scientist to work with hydrochloric acid was Persian physician and alchemist Rhazes (ar-Razi; c. 64-c. 935), one of the most outstanding scientific minds of the medieval period. Alchemists, who in some ways were the precursors of true chemists, believed that base metals such as iron could be turned into gold. Of course this is not possible, but alchemists in about 1200 did at least succeed in dissolving gold using a mixture of hydrochloric and nitric acids known as aqua regia. The first modern scientist to work with chlorine was Swedish chemist Carl W. Scheele (1742-1786), who also discovered a number of other elements and compounds, including barium, manganese, oxygen, ammonia, and glycerin. However, Scheele, who isolated it in 1774, thought that chlorine was a compound; only in 1811 did English chemist Sir Humphry Davy (1778-1829) identify it as an element. Another chemist had suggested the name halogen for the alleged compound, but Davy suggested that it be called chlorine instead, after the Greek word chloros , which indicates a sickly yellow color. Uses Of Chlorine: The dangers involved with chlorine have made it an effective substance to use against stains, plants, animals—and even human beings. Chlorine gas is highly irritating to the mucous membranes of the nose, mouth, and lungs, and it can be detected in air at a concentration of only 3 parts per million (ppm). The concentrations of chlorine used against troops on both sides in World War I (beginning in 1915) was, of course, much higher. Thanks to the use of chlorine gas and other antipersonnel agents, one of the most chilling images to emerge from that conflict was of soldiers succumbing to poisonous gas. Yet just as it is harmful to humans, chlorine can be harmful to microbes, thus preserving human life. As early as 1801, it had been used in solutions as a disinfectant; in 1831, its use in hospitals made it effective as a weapon against a cholera epidemic that swept across Europe. Another well-known use of chlorine is as a bleaching agent. Until 1785, when chlorine was first put to use as a bleach, the only way to get stains and unwanted colors out of textiles or paper was to expose them to sunlight, not always an effective method. By contrast, chlorine, still used as a bleach today, can be highly effective—a good reason not to use regular old-fashioned bleach on anything other than white clothing. Since the 1980s, makers of bleaches have developed all-color versions to brighten and take out stains from clothing of other colors. ) Calcium hydrocholoride (CaOCl), both a bleaching powder and a disinfectant used in swimming pools, combines both the disinfectant and bleaching properties of chlorine. This and the others discussed here are just some of many, many compounds formed with the highly reactive element chlorine. Particularly notable—and controversial—are compounds involving chlorine and carbon. Chlorine And Organic Compounds: Chlorine bonds well with organic substances, or those containing carbon. In a number of instances, chlorine becomes part of an organic polymer such as PVC (polyvinyl chloride), used for making synthetic pipe. Chlorine polymers are also applied in making synthetic rubber, or neoprene. Due to its resistance to heat, oxidation, and oils, neoprene is used in a number of automobile parts. The bonding of chlorine with substances containing carbon has become increasingly controversial because of concerns over health and the environment, and in some cases chlorine-carbon compounds have been outlawed. Such was the fate of DDT, a pesticide soluble in fats and oils rather than in water. When it was discovered that DDT was carcinogenic, or cancer-causing, in humans and animals, its use in the United States was outlawed. Other, less well-known, chlorine-related insecticides have likewise been banned due to their potential for harm to human life and the environment. Among these are chlorine-containing materials once used for dry cleaning. Also notable is the role of chlorine in chlorofluorocarbons (CFCs), which have been used in refrigerants such as Freon, and in propellants for aerosol sprays.  CFCs tend to evaporate easily, and concerns over their effect on Earths atmosphere have led to the phasing out of their use. Introduction: Bromine is a foul-smelling reddish-brown liquid whose name is derived from a Greek word meaning stink. With a boiling point much lower than that of water—137. 84 °F (58. 8 °C)—it readily transforms into a gas. Like other halogens, its vapors are highly irritating to the eyes and throat. It is found primarily in deposits of brine, a solution of salt and water. Among the most significant brine deposits are in Israels Dead Sea, as well as in Arkansas and Michigan. Credit for the isolation of bromine is usually given to French chemist Antoine-Jerome Balard (1802-1876), though in fact German chemist Carl Lowig (1803-1890) actually isolated it first, in 1825. However, Balard, who published his results a year later, provided a much more detailed explanation of bromines properties. The first use of bromine actually predated both men by several millennia. To make their famous purple dyes, the Phoenicians used murex mollusks, which contained bromine. (Like the names of the halogens, the word Phoenicians is derived from Greek—in this case, a word meaning red or purple, which referred to their dyes. Today bromine is also used in dyes, and other modern uses include applications in pesticides, disinfectants, medicines, and flame retardants. At one time, a compound containing bromine was widely used by the petroleum industry as an additive for gasoline containing lead. Ethylene dibromide reacts with the lead released by gasoline to form lead bromide (PbBr 2 ), referred to as a scavenger, because it tends to clean the emissions of lead-containing gasoline. However, leaded gasoline was phased out during the late 1970s and early 1980s; as a result, demand for ethylene dibromide dropped considerably. Halogen Lamps: The name halogen is probably familiar to most people because of the term halogen lamp. Used for automobile headlights, spotlights, and floodlights, the halogen lamp is much more effective than ordinary incandescent light. Incandescent heat-producing light was first developed in the 1870s and improved during the early part of the twentieth century with the replacement of carbon by tungsten as the principal material in the filament, the area that is heated. Tungsten proved much more durable than carbon when heated, but it has a number of problems when combined with the gases in an incandescent bulb. As the light bulb continues to burn for a period of time, the tungsten filament begins to thin and will eventually break. At the same time, tungsten begins to accumulate on the surface of the bulb, dimming its light. However, by adding bromine and other halogens to the bulbs gas filling—thus making a halogen lamp—these problems are alleviated. As tungsten evaporates from the filament, it combines with the halogen to form a gaseous compound that circulates within the bulb. Instead of depositing on the surface of the bulb, the compound remains a gas until it comes into contact with the filament and breaks down. It is then redeposited on the filament, and the halogen gas is free to combine with newly evaporated tungsten. Though a halogen bulb does eventually break down, it lasts much longer than an ordinary incandescent bulb and burns with a much brighter light. Also, because of the decreased tungsten deposits on the surface, it does not begin to dim as it nears the end of its life. Introduction: First isolated in 1811 from ashes of seaweed, iodine has a name derived from the Greek word meaning violet-colored—a reference to the fact it forms dark purple crystals.  During the 1800s, iodine was obtained commercially from mines in Chile, but during the twentieth century wells of brine in Japan, Oklahoma, and Michigan have proven a better source. Uses And Applications: Among the best-known properties of iodine is its importance in the human diet. The thyroid gland produces a growth-regulating hormone that contains iodine, and lack of iodine can cause a goiter, a swelling around the neck. Table salt does not naturally contain iodine; however, sodium chloride sold in stores usually contains about 0. 01% sodium iodide, added by the manufacturer. Iodine was once used in the development of photography: During the early days of photographic technology, the daguerreotype process used silver plates sensitized with iodine vapors. Iodine compounds are used today in chemical analysis and in synthesis of organic compounds. Introduction: Just as fluorine has the distinction of being the most reactive, astatine is the rarest of all the elements. Long after its existence was predicted, chemists still had no luck finding it in nature, and it was only created in 1940 by bombarding bismuth with alpha particles (positively charged helium nuclei). The newly isolated element was given a Greek name meaning unstable. Indeed, none of astatines 20 known isotopes is stable, and the longest-lived has a half-life of only 8. 3 hours. This has only added to the difficulties involved in learning about this strange element, and therefore it is difficult to say what applications, if any, astatine may have. The most promising area involves the use of astatine to treat a condition known as hyperthyroidism, related to an overly active thyroid gland.

Origins Of Our Economic Worldview Essay Example for Free

Origins Of Our Economic Worldview Essay Nature is a wonderful tool that heals all by itself and it is a very well known fact. It is said that if nature is provided with enough time she would heal herself and that includes the affects of human activities too. But the basic question to this argument is the time duration or in other words what is the time taken to heal such wounds? It has been estimated that the unknown civilization that was wiped out of the Easter Island was due to deforestation. Human interventions devastated the ecology and subsequently themselves and still after about 1000 years the island is still grassland with little foliage. This is the point that was instrumental in developing the factors of ecological economics. Ecological economics is regarded as a subfield of economics that deals with issues that are, broadly speaking, related to the ecological concerns. The main purpose of Ecological economics is to use the universal methods of economics, mainly and mostly neo classical, to achieve its goal. According to Davis Lamb the ecological economics’ focal point is to centralize on the perception of externality of environment. In other word some or more of the outcomes of a commotion are not evaluated in accordance to its fiscal result. As an example he states that when the pollution level of a given state reaches its optimum level the price of the producer of this pollution subject should be taken into consideration otherwise the balance would be in the brink of commotion. Therefore it is encouraged to formulate the outcome of a polluting medium in respect of utility oriented price format. According to the Coase Theorem the assigning property rights is based on a fact that there is all probability that this application would lead to an optimal solution of ecological policies of economics whereby in accordance to regardless of who receives them, the basic cost of transaction would reveal an inconsequential state where the stake holders of the negotiating parties would be minimized. In other words, if there is a factory operating over a substantial period of time and polluting the surrounding area all along the way and the local population is suffering for that reason then a negotiation committee should be set up to find a perfect formulation that would help either way. One of the most logical conclusion could be the factory would be held responsible for the pollution and the suffering of the local population as the factory is polluting and banishing the local population’s right to proper and healthy environment. For this the factory should pay the local population as a price for a better living surrounding. Ecological economics in today’s world is one of the most relevant issues concerned. It should be remembered that the perception of Ecological economics is directly included into the peripheral view of the subject economics and is inseparable in nature. It is also believed that Ecological economics is in actuality three-fifths of ecology as per economist Mike Nickerson. Ecological economics is often regarded as a consolidation of conventional economics and political economy. Ecological finance and theories of natural capitalism are also highly influenced by the variables of Ecological economics. According to the DETR, government policies will strive to ensure that the countryside is environmentally protected while at the same time maintaining its working nature, thereby contributing to national prosperity as part of a competitive economy. The government stresses the need for social, economic and environmental concerns all to be considered together. Whether though the current legislation is in fact meeting such objectives is debatable. The most substantial protection for the habitat in the UK from the point of vie of Ecological economics is to be found in the Wildlife and Countryside Act 1981 which specifically provides for the designation of certain areas, known under the Act as ‘sites of special scientific interest’ or SSSI’s, for protection. The Act (Section 28(1) WCA 1981) provides for guidelines on designation criteria with the effect that designation will be likely if the area is ‘of special interest by reason of any of its flora, fauna, or geological or physiographical features’. (McEldowney, 1999) In fact, if the area in question satisfies these criteria, then the Nature Conservancy Council must deem the areas to be under strict regulation. This ruling was most notably exemplified by the case of R v Nature Conservancy Council, ex parte London Brick Property Ltd. In conclusion it could be stated that despite the first glance opinions by the scientific and economic communities Ecological economics and habitat protection suggests that equal importance is in fact proffered to the environment than it is to the economic interests of those bound by the laws, in practice the laws have been implemented in such a fashion as to, in the main, permit an acceptable level of a balancing of interests of all concerned, a result which is not easily reached and is therefore to be applauded.

Utilisation of Wind Energy for High Rise Building Power

Utilisation of Wind Energy for High Rise Building Power Introduction The price of conventional energy is on the rise, due to the ever-widening gap between demands and supply. The main reason for such shortages is the depletion in natural resources, such as coal, which is the main fuel used for electrical energy generation. Since these fuels are made up of carbon compounds, burning them has rapidly increased the amount of carbon dioxide in the atmosphere over the last 100 years. This has brought about a chain reaction of hazards such as global warming, climate change, destruction of ecosystems, etc with predictions for adverse outcomes in the future. In response to this threat and to initiate an end to such processes, the UN agreed the Kyoto Protocol in Japan in 1997. This requires industrialised nations to reduce greenhouse gas emissions by 5% of 1990 levels by 2008-2012. The UK has agreed to meet this target and furthered its promise by setting a goal of 50% reduction in carbon emissions by 2050[ ]. Part of its government energy policy is to increase the contribution of electricity supplied by renewable energy to 10% by 2010 (Blackmore P, 2004). A similar promise has been undertaken by many world nations, which has led to a plethora of new and innovative methods for power generation. Renewable is the key to climate friendly forms of energy, due to the absence of emissions detrimental to the environment (Stiebler M, 2008). It includes energy derived from sunlight, wind, wave, tides and geothermal heat. Out of the afore mentioned resources, geothermal heat is restricted to only limited locations on the globe while wave and tidal power is still in its research stage. Thus sunlight and wind are the key elements that can be tapped for energy generation. However, on comparison between the two systems, wind energy systems are more advantageous both in availability of resources and cost of generation. This report mainly focuses on wind energy, with a keen interest on harvesting it for ventilation and power generation purposes in high-rise buildings. Plan forms that aid this purpose will be studied using Computational Fluid Dynamics to understand the flow of wind in and around a thirty-storey structure and the building configuration well suited for natural ventilation and wind turbine integration would be identified at the end of the test. To obtain a complete picture of wind flow patterns and to closely mimic real life situations, the wind will be simulated from different directions at different wind speeds. Wind energy Wind is the term used for air in motion and is usually applied to the natural horizontal motion of the atmosphere (Taranath Bungale S, 2005). It is brought about by the movement of atmospheric air masses that occur due to variations in atmospheric pressure, which in turn are the results of differences in the solar heating of different parts of the earth’s surface (Boyle G, 2004). At a macro level wind profile differs from place to place depending on geographic location and climatic conditions while in a microstate the immediate physical environment of a particular place modifies the nature of the winds. For example, the velocity of the wind recorded in the countryside which has acres of unobstructed grassland would be greater than that recorded in a city dominated by skyscrapers. Hence to obtain a clear idea of the wind characteristic corresponding to a particular area the wind rose is utilized. They are based on metrological observations and depict the varying wind speeds experienced by a site at different times of the year together with the frequency of different wind directions [ ]. It is the first tool consulted to judge the wind resources of a site and its ability to support power generation. The winds have been tapped from ancient times by means of ship sails, windmills, wind catchers, etc. The history of windmills goes back more than 2000 years (Stiebler M, 2008) when they were predominantly used for grinding grain and pumping water. However, the breakthrough occurred when Charles.F.Brush erected the first automatically operating wind turbine at Ohio in 1888 [ ]. It was fabricated using wood and had a rotor diameter of 17m with 144 blades. The system recorded very low efficiency and was mainly used to charge batteries. The reason behind the poor efficiency was due to the large number of blades, which was later discovered by Poul la Cour who introduced fewer blades into his wind turbine. Though such developments were achieved at an early stage in innovation, it was not until 1980 that the prominent application of renewable energies was sought after (Boyle G, 2004). Wind energy is the harnessing of the kinetic energy prevalent in moving air masses. This kinetic energy for any particular mass of moving air (Boyle G, 2004) is given by the formula: K.E = 0.5mV ² where, m – mass of the air (kg) and V – wind velocity (m/s). However this mass of moving air per second is: m = air density x volume of air flowing per second m = air density x area x velocity   Thus, m = rAV where, r – density of air at sea level = 1.2256 kg/m ³ and A – area covered by the flowing air (m ²) Substituting this value of m in the former equation, K.E. = 0.5rAV ³ (J/s) But energy per unit of time is power and hence the above equation is the power available from the wind. It is also evident that the power is directly proportional to thrice the wind velocity. In other words even a marginal increase in wind speed would yield three folds of the nominal power. This is the critical fact based on which the whole energy process is evolved. However not all of this power can be exhausted since it would lead to nil outflow through the wind turbine, that is no flow of air behind the rotor. This would lead to no flow of air over the turbine causing total failure of the system. According to Albert Betz the maximum amount of power that can be harnessed from the wind is 59.3%. This is often referred to as the Betz limit and has been proven by modern experiments. Some of the advantages of wind energy include: It is based on a non-exhaustive resource and hence can be harnessed for generations. It is a clean and eco friendly way of producing energy. In its working lifetime, the wind turbine produces eighty times the amount of energy that goes into its manufacturing and thus has diminishable net impact on the environment. It does not require any additional resources such as water supply unlike conventional power generation. It can boost the economy of the region (wind farms). Wind turbines: Wind turbines are the modern day adaptations of the yesteryear windmills but unlike their counterparts they are mainly used for power generation. These new age systems come in different shapes and have various configurations, the well established of them all are the Horizontal axis wind turbine and the Vertical axis wind turbine. Write a brief about horizontal wind turbines and vertical wind turbines. BUilding integrated Wind Turbines (BUWT): Building integrated wind turbines are associated with buildings designed and shaped with wind energy in mind (Stankovic S et al, 2009). They are relatively a new way of harnessing energy that is gaining popularity at a quick pace. Small scale wind turbines on house roofs and retrofitting also fall under this category. The design of BUWTs is a complicated affair and involves the careful consideration of various factors. Since turbines are fixed into the building’s fabric its impact on the environment, building’s response and needs of its owners and occupants need to be weighed equally. Also numerous design decisions such as planning, structure, services, construction and maintenance depend on this single process (Stankovic S et al, 2009). With the increase in the scale of the proposal the importance of these factors increases simultaneously. The proposal generally spans from the number, scale, type and location of the turbines together with its annual energy yield and design life. A good BUWT based building should be a wholesome design that does not prejudice the buildings efficient functioning for energy generation. Generic options for BUWTs: Stankovic S et al (2009) explains that the wind turbines can be fixed on to a building in enumerable ways. Each method can accomplish a different level of power depending on the type of turbine used and the form of the building it is mounted upon. On top of a square/ rectangular building: This configuration is on the principle that the wind velocity increases with height and hence the amount of energy generated would be of a higher order (10% increase with wind acceleration). An added advantage is that the turbine would experience relatively little turbulence. But access to the turbine for maintenance and decommissioning works may be difficult. If mounted on tall buildings the turbines may threaten the visual quality of the skyline. On top of a rounded building: This case is very similar to the previous configuration except that with the use of rounded faà §ade the mean tower height can be considerably diminished. Also the rounded profile influences the local acceleration (15% increase in energy). The low tower height favors easy access to the turbine but leads to blade flicker and noise issues. Concentrator on top of a rounded building: This case is well suited to areas with bi-directional winds (20% energy increase over a free standing equivalent due to local acceleration). Vertical axis wind turbines are better suited for this feature while Horizontal axis wind turbines need to be suitably altered to achieve the same status. The building spaces that act as concentrators may be inhabited with suitable acoustical treatment. This case also encounters the same drawbacks as listed in the previous case. Square concentrator within a building faà §ade: As before, this configuration takes advantage of the higher quality winds at higher altitudes and local acceleration thereby achieving 25% increase in energy and 40% increase for bi-directional winds. This option is best suited for buildings with narrower profiles. There may be a loss in the saleable area of the building but the aperture can be converted into an exclusive feature such as a sky garden. The opening also relieves the wind loading on the building’s facade leading to simpler structural solutions. Vertical axis wind turbine is the only choice for integration due to its square swept area. Circular concentrator within a building faà §ade: This is very similar to the square concentrator except the opening is accustomed to hold pitch controlled horizontal axis wind turbines with fixed yaw. Also, a 35% increase for uniform wind and 50% increase in energy for bi-directional winds are achievable in this method. But on the down side, this technique is more expensive due to the cylindrical shroud. On the side of a building: In this technique, an increase in 80-90% in energy than the freestanding equivalents is achievable only if the building form is optimized to the local wind character. Only reliable vertical axis wind turbines can be used for power generation due to access issues. For higher swept area, more number of turbines should be used. Between multiple building forms: This type of an option opens out many doors for a range of architectural forms. Unlike the previous cases, the buildings orientation, form, shape and spacing play key roles in the performance of the turbines. Vertical axis wind turbines are better suited for this purpose. Guidelines for BUWT’s: The following are some guidelines outlined by Stankovic S et al (2009) for incorporating wind turbines into a structure: BUWTs should be tailored to the specific site for good results. Adequate wind resources should be available on site. If however if the site is under resourced steps are to be adopted to deliberately elevate the quality of the wind through the buildings form or turbine. The impact of its surroundings should also be considered before commissioning such a project. The dominating wind direction and its intensity should be observed from meteorological data. This would help in determining the form and orientation of the building together with finalizing the position of the wind turbine to make the most out of the available resource. Environmental impact assessment corresponding to the site should be carried out to foresee the adverse effects the turbines may create. Acoustic isolation may be sought for in some areas within the building if it lies at close proximity to the rotor. Natural ventilation and day lighting qualities of the building may be challenged and forced to settle for artificial means. The type and position of openings, external shading devices, smoke extracts etc should be handled with appropriate care to avoid draught winds. Access to the wind turbines for maintenance and decommissioning must be provided suitably. The aesthetic quality of the mounted turbines must harmonize with its surroundings and should not over power the pedestrians at ground level. To this end well suited screening devices such as canopies, screens and landscape may be utilized as per the necessity. The overall success of BUWT project depends on its ability to deliver the expected power. Inability to comply with this effect would result in the failure of its intended purpose from both an environmental and design point of view. Thus the electricity demand of the building and the level to which this would be met with should be estimated prior to turbine design to secure maximum benefits. Wind flow prediction and energy yields: For any project to be successful, Wind flow and building design (Taranath Bungale S, 2005) When the air moves in a vertical direction it is referred to as a current. These currents play a major role in meteorology whereas the gradual decrease in wind speed and high turbulence of the horizontal motion of air, at the ground level, are vital in building engineering. In urban areas, this zone of turbulence extends to a height of approximately one quarter of a mile aboveground and is called the surface boundary layer. Above this layer, the horizontal airflow is no longer influenced by the ground effect. The wind speed at this height is known as the gradient wind speed, and it is precisely in this boundary layer where most human activity is conducted. Characteristics of wind: The flow of wind is complex because many flow situations arise from the interaction of wind with structures. A few characteristics of wind include: Variation of wind velocity with height: The viscosity of air reduces its velocity adjacent to the earth’s surface to almost zero. A retarding effect occurs in the wind layers near the ground, and these layers in turn successively slow the outer layers. The slowing down is reduced at each layer as the height increases, and eventually becomes negligibly small. The height at which velocity ceases to increase is called the gradient height, and the corresponding velocity, the gradient velocity. At heights of approximately 366m aboveground, the wind speed is virtually unaffected by surface friction, and its movement is solely dependant on prevailing seasonal and local wind effects the height through which the wind speed is affected by topography is called the atmospheric boundary layer. Wind turbulence: Motion of wind is turbulent and it occurs in wind flow because air has a very low viscosity-about one-sixteenth that of water. Any movement of air at speeds greater than 0.9 to 1.3 m/s is turbulent, causing air particles to move randomly in all directions. Vortex shedding: In general, wind buffering against a bluff body such as a rectangular building gets diverted in three mutually perpendicular directions. However, only the longitudinal winds and the transverse winds or crosswinds are considered in civil engineering. When a free flowing mass of air encounters a building along its path, the originally parallel upwind streamlines are displaced on either side of the building. This results in spiral vortices being shed periodically from the sides into the downstream flow of the wind, called the wake. At relatively low wind speeds the vortices are shed, that is, break away from the surface of the building and an impulse is applied in the transverse direction. Distribution of pressures and suctions: When air flows around the edges of a structure, the resulting pressures at the corners are much in excess of the pressures on the center of elevation. This has been evident by the damages caused to corner windows, eave and ridge tiles, etc in windstorms. Wind tunnel studies conducted on scale models of buildings indicate that three distinct pressure areas develop around the building. They are: Positive pressure zone on the upstream face (Region 1) Negative pressure zone at the upstream corners (Region 2) Negative pressure zone on the downstream face (Region 3) The highest negative pressures are created in the upstream corners designated as Region 2. Wind pressures on a buildings surface are not constant, but fluctuate continuously. The positive pressure on the upstream or the windward face fluctuates more than the negative pressure on the downstream or the leeward face. The negative pressure region remains relatively steady as compared to the positive pressure zone. The fluctuation of pressure is random and varies from point to point on the building surface. Nearby buildings can have a significant influence on wind forces. If they are the same height as the structure being considered then they will mostly provide shelter, although local wind loads can be increased in some situations. Where surrounding buildings are significantly taller they will often generate increased wind loading (negative shelter) on nearby lower structures. Shelter can result from either from the general built-environment upwind of the site or from the direct shielding from specific individual upwind buildings (Blackmore P, 2004). Natural ventilation The three natural ventilation airflow paths in buildings are (Pennycook, 2009): Cross ventilation Single-sided ventilation Passive stack ventilation Advantages of cross ventilation: Greater rates of ventilation can be achieved under amicable weather conditions. Can be utilized for deep-plan spaces with operable windows on the external wall. Incumbents have control over ventilation. Relatively cost free. Can be incorporated with thermal masses. However, it has certain limitations such as: Internal space layout must be hindrance free for easy, clear flow of air. Internal partitions must be within 1.2m height and tall cupboards must be placed alongside the windows. Natural ventilation can occur only under the presence of suitable winds. Poor planning and positioning of windows may cause disruptive draughts and gusts. Winter ventilation is problematic. Unsuitable for buildings located in noisy and pollution prone environments. The requirements of fresh air supply are governed by the type of occupancy, number and activity of the occupants and by the nature of any processes carried out in the space (Koenigsberger et al, 2001). When natural ventilation is stipulated for good indoor air quality, the amount and nature of the dominant pollutant source in the space should be identified. Based on this data the ventilation rate for the space can be calculated such that the pollution level does not cross a preset specific mark. Generally the concentration of the pollutants decreases with the increase in airflow rate (Figure –1). However, in terms of thermal comfort especially during winter the heating requirement of the building will increase with the ventilation rate. This demand varies with time, wind characteristics of the place, opening and closing of windows and doors by its occupants and the thermal state of the building. In summer, cooling is ideal for both the building and its occupants to prevent internal heat gains. By directing the high velocity wind around the human body the evaporative rate at the skins surface can be increased thereby achieving a cooling sensation. The recommended upper limit of indoor air movement is 0.8 m/sec, which permits the inhabitants to occupy a space about 2 °C warmer and 60% relative humidity with optimum comfort. The traditional way to cool buildings is to provide large openings along the exterior wall with the principle that higher the ventilation rate greater the loss of heat to the external environment. But such an arrangement would work only when the outdoor te mperature is in the range of comfort zone. When controlled indoor environments are desired especially during the occupancy period’s night ventilation is recommended. In this technique the building is cooled at night so that it can absorb the heat generated during the day (Allard F, 1998). Based on wind tunnel experimental observations, the factors that affect the indoor airflow are: Orientation: External features: Cross-ventilation: Position of openings: Size of openings: Control of openings: Literature review The following are studies that have been made of different aspects of wind using Computational Fluid dynamics. CFD evaluation of wind speed conditions in passages between parallel buildings: This analysis undertaken by Blocken B et al (2007) mainly focuses on the wind speed conditions in passages between parallel buildings in combination with the accuracy of the commercial CFD code Fluent 6.1.22 when the wall-function roughness modifications are applied to them. The Venturi effect is also studied to determine the amount of increase in wind speed in the passage due to the decrease in flow section. The results obtained were compared with various previously proven experiments carried out by experts in the field. As the title indicated the case undertaken involves a pair of rectangular buildings measuring 40m x 20m x 20m, placed adjacent to each other and separated by a narrow passage. The width of the passage is widened (for example, 2, 4, 6, 8, 10, 15, 20, 30, 40, 60, 80, 100 m) with every case to clearly understand the Venturi effect. The dimension of the computational domain is 20.5x14x18m3; the whole setup is placed at a distance of 5m from the inlet and simulated with a wind speed of 6.8m/sec based on initial results. The results recorded at the end of the simulation process are discussed as follows. They are based on the amplification factor, which is defined as the ratio of the mean wind speed at a certain location to the mean wind speed at the same location without the buildings present. As such it is a direct indication of the effect of the buildings on the wind speed (Blocken B et al, 2007). Pedestrian level wind profile: In context to this research, for narrow passages (example w=2m) this amplification factor occurs maximum at the centerline immediately behind the entrance. When the distance between the buildings are slightly increased (example w=10m), the flow streams deflecting off the inner edges of the buildings combine into a large jet stream and records an increase in the amplification factor. However this property is lost when the width of the passage is of a high order (example w=30m). Overall wind profile: To understand the overall wind profile, six vertical lines were identified along the passage’s center plane for the case of w=6m. The lines depicted the fact that there was an increase in the wind speed at the ground level due to the downdraft of the wind along the front faà §ade of the building and a decrease in wind speed at the end of the passage due to the exit of flow from the passage. Also for these cases, there was no significant increase in the wind speed with the increase in height. Flow rates at different points in the passage: To evaluate the Venturi-effect three fluxes were defined, one along the vertical plane, another along the horizontal plan and the final being similar to the former one but in the absence of the buildings. When the flow rate was calculated for narrow passages, it stated an increase in wind speed by only 8% due to the Venturi effect. However for larger widths the flow rate was lower than the free-field flux. This shows that the wind has a tendency to flow over and around the building rather than be forced through the passage as previously believed. Thus there is a lack of strong Venturi effect and the flow in the passage can be attributed as the channeling effect for these cases. The research also concluded that there were discrepancies in the CFD results due to the use of the roughness factor and advised future users to simulate an empty field before positioning the buildings to clearly identify the difference in results. Further research into the Venturi effect was also implied. Computational analysis of wind driven natural ventilation in buildings: Evola G and Popov V (2006) research focuses on the application of three-dimensional Reynolds Averaged Navier-Strokes (RANS) modeling on wind driven natural ventilation with specific detail to the pressure distribution and flow pattern within the building. The various cases would be simulated with the standard k-e model and the Renormalization Group theory (RNG). Within the framework of natural ventilation both single sided ventilation and cross ventilation would be studied and the results obtained using CFD will be compared with LES models and empirical methods for its reliability.  Ã‚  Ã‚   The building undertaken consists of a 250mm x 250mm x 250mm cube punctured with a centrally located 84mm x 125 mm opening on the wind ward side (Case 1). In Case 2 the door like opening is placed on the leeward side and in Case 3 both the openings are retained to test the cross ventilation principle. On comparison between the CFD results obtained for Case 1 and 2, Case 2 portrays a better flow pattern especially at the mouth of the opening. This leads to a better ventilation rate than Case 1 though in contrast to the theoretical data that good ventilation rate and flow patterns are achievable only when the opening faces the incoming winds. To establish the phenomenon further experimentation into the field was suggested. Between Cases 1, 2 and 3, cross ventilation clearly stands out as the best option of them all, both in terms of velocity and distribution. Also the study concluded that the measured RNG results matched approximately to the theoretical results of Cases 1 and 2. But a significant amount of deviation was observed in Case 3. The RNG model was only slightly intense than the k-e model generally used. The research also concluded that there were discrepancies in the CFD results due to the use of the roughness factor and advised future users to simulate an empty field before positioning the buildings to clearly identify the difference in results. Further research into the Venturi effect was also implied. CFD modeling of unsteady cross-ventilation flows using LES: This research undertaken by Cheng-Hu Hu et al (2008) employs the LES method to investigate the fluctuating ventilation flow rate induced by the wind for a cross-ventilated building. The results from CFD were compared with those previously acquired from wind tunnel tests.   Ã‚   The building proposed for the study consists of a rectangular box with two openings of equal size located opposite to each other. The wind is simulated from 0 °(Case 1) and 90 °(Case 2) to the building at a rate of 1m/sec, to study the flow pattern in and around it. When the air approaches the building the ventilation rate is unsteady at the mouth of the openings due to turbulence and in the flow separation layer due to shear. In Case 1 the wind is accelerated through the opening and directed downwards inside the building. This phenomenon brings about a circulation of the internal air before guiding the wind upwards and out through the window on the leeward side of the building. The air exchange occurs due to the mean flows through the opening. In Case 2 where the wind is parallel to the windows, the air moves in and exits rapidly causing fluctuating flows thereby leading to air exchange. In this case turbulence prone areas are formed at the rear of the building. When these results were compared with the wind tunnel data, Case 1 portrayed similarities while Case 2 had major deviations. Further study was proposed for understanding the reason behind such deviations. Case studies The Bahrain world trade centre was the world’s first building to ‘aesthetically incorporate commercial wind turbines into the fabric of the building’ [ ]. The complex consists of a three-storied sculpted podium and basement from where the 240m high towers rise up into the sky. The two towers comprise of 51 floors each and are connected by means of three, 31.5m span bridges at 60m, 96m and 132m levels [ ]. They are oval in section for aerodynamic reasons and follow a shallow V-shape in plan for adequate blade clearance. Sitting on each of this 70 ton spandrel is an 11-ton nacelle to which the industry approved horizontal axis wind turbines are fixed by special means. The turbine has a rotor diameter of 29m and is stall controlled with centrifugally activated feathering tips for air brakes (Killa S Smith Richard F, 2008). The turbines are oriented facing the Arabian Gulf intercepting the path of the dominant winds. The decision to harness the prevailing wind was thought of from the initial stage drawing inspiration from ‘the regional wind towers and the vast sails of the traditional Arabian Dhow which utilise the wind to drive them forward’. Numerous Computational fluid dynamics models and wind tunnel tests were carried out to determine the final building form. The result was a skyward tapering, elliptical structure, carved out by the wind that functions as aerofoil sections (Wood A, 2008). The shape and spatial relationship of the towers aid in adhering the wind in a â€Å"S’ flow whereby the center of the wind stream remains nearly perpendicular to the turbine within a 45 ° wind azimuth, either side of the central axis (Killa S Smith Richard F, 2008). This increases the turbine efficiency, number of working hours and minimizes the stress on the blade caused by yawing [ ]. Furthermore, the two towers were placed such that they create a ‘V’ shaped space in between them, as well as a negative pressure behind the blocks, thus creating an opportunity for the Venturi effect to accelerate wind velocity onto the turbines (Binder G, 2006) by as much as 30% more than the source wind (Killa S Smith Richard F, 2008). The tapering profile combined with the increased onshore wind velocity at higher altitudes creates a near equal regime of wind speed on each of the three turbines, irrespective of its location, allowing them to rotate at the same speed and generate approximately the same amount of energy (Wood A, 2008). Table 1: Annual energy output Utilisation of Wind Energy for High Rise Building Power Utilisation of Wind Energy for High Rise Building Power Introduction The price of conventional energy is on the rise, due to the ever-widening gap between demands and supply. The main reason for such shortages is the depletion in natural resources, such as coal, which is the main fuel used for electrical energy generation. Since these fuels are made up of carbon compounds, burning them has rapidly increased the amount of carbon dioxide in the atmosphere over the last 100 years. This has brought about a chain reaction of hazards such as global warming, climate change, destruction of ecosystems, etc with predictions for adverse outcomes in the future. In response to this threat and to initiate an end to such processes, the UN agreed the Kyoto Protocol in Japan in 1997. This requires industrialised nations to reduce greenhouse gas emissions by 5% of 1990 levels by 2008-2012. The UK has agreed to meet this target and furthered its promise by setting a goal of 50% reduction in carbon emissions by 2050[ ]. Part of its government energy policy is to increase the contribution of electricity supplied by renewable energy to 10% by 2010 (Blackmore P, 2004). A similar promise has been undertaken by many world nations, which has led to a plethora of new and innovative methods for power generation. Renewable is the key to climate friendly forms of energy, due to the absence of emissions detrimental to the environment (Stiebler M, 2008). It includes energy derived from sunlight, wind, wave, tides and geothermal heat. Out of the afore mentioned resources, geothermal heat is restricted to only limited locations on the globe while wave and tidal power is still in its research stage. Thus sunlight and wind are the key elements that can be tapped for energy generation. However, on comparison between the two systems, wind energy systems are more advantageous both in availability of resources and cost of generation. This report mainly focuses on wind energy, with a keen interest on harvesting it for ventilation and power generation purposes in high-rise buildings. Plan forms that aid this purpose will be studied using Computational Fluid Dynamics to understand the flow of wind in and around a thirty-storey structure and the building configuration well suited for natural ventilation and wind turbine integration would be identified at the end of the test. To obtain a complete picture of wind flow patterns and to closely mimic real life situations, the wind will be simulated from different directions at different wind speeds. Wind energy Wind is the term used for air in motion and is usually applied to the natural horizontal motion of the atmosphere (Taranath Bungale S, 2005). It is brought about by the movement of atmospheric air masses that occur due to variations in atmospheric pressure, which in turn are the results of differences in the solar heating of different parts of the earth’s surface (Boyle G, 2004). At a macro level wind profile differs from place to place depending on geographic location and climatic conditions while in a microstate the immediate physical environment of a particular place modifies the nature of the winds. For example, the velocity of the wind recorded in the countryside which has acres of unobstructed grassland would be greater than that recorded in a city dominated by skyscrapers. Hence to obtain a clear idea of the wind characteristic corresponding to a particular area the wind rose is utilized. They are based on metrological observations and depict the varying wind speeds experienced by a site at different times of the year together with the frequency of different wind directions [ ]. It is the first tool consulted to judge the wind resources of a site and its ability to support power generation. The winds have been tapped from ancient times by means of ship sails, windmills, wind catchers, etc. The history of windmills goes back more than 2000 years (Stiebler M, 2008) when they were predominantly used for grinding grain and pumping water. However, the breakthrough occurred when Charles.F.Brush erected the first automatically operating wind turbine at Ohio in 1888 [ ]. It was fabricated using wood and had a rotor diameter of 17m with 144 blades. The system recorded very low efficiency and was mainly used to charge batteries. The reason behind the poor efficiency was due to the large number of blades, which was later discovered by Poul la Cour who introduced fewer blades into his wind turbine. Though such developments were achieved at an early stage in innovation, it was not until 1980 that the prominent application of renewable energies was sought after (Boyle G, 2004). Wind energy is the harnessing of the kinetic energy prevalent in moving air masses. This kinetic energy for any particular mass of moving air (Boyle G, 2004) is given by the formula: K.E = 0.5mV ² where, m – mass of the air (kg) and V – wind velocity (m/s). However this mass of moving air per second is: m = air density x volume of air flowing per second m = air density x area x velocity   Thus, m = rAV where, r – density of air at sea level = 1.2256 kg/m ³ and A – area covered by the flowing air (m ²) Substituting this value of m in the former equation, K.E. = 0.5rAV ³ (J/s) But energy per unit of time is power and hence the above equation is the power available from the wind. It is also evident that the power is directly proportional to thrice the wind velocity. In other words even a marginal increase in wind speed would yield three folds of the nominal power. This is the critical fact based on which the whole energy process is evolved. However not all of this power can be exhausted since it would lead to nil outflow through the wind turbine, that is no flow of air behind the rotor. This would lead to no flow of air over the turbine causing total failure of the system. According to Albert Betz the maximum amount of power that can be harnessed from the wind is 59.3%. This is often referred to as the Betz limit and has been proven by modern experiments. Some of the advantages of wind energy include: It is based on a non-exhaustive resource and hence can be harnessed for generations. It is a clean and eco friendly way of producing energy. In its working lifetime, the wind turbine produces eighty times the amount of energy that goes into its manufacturing and thus has diminishable net impact on the environment. It does not require any additional resources such as water supply unlike conventional power generation. It can boost the economy of the region (wind farms). Wind turbines: Wind turbines are the modern day adaptations of the yesteryear windmills but unlike their counterparts they are mainly used for power generation. These new age systems come in different shapes and have various configurations, the well established of them all are the Horizontal axis wind turbine and the Vertical axis wind turbine. Write a brief about horizontal wind turbines and vertical wind turbines. BUilding integrated Wind Turbines (BUWT): Building integrated wind turbines are associated with buildings designed and shaped with wind energy in mind (Stankovic S et al, 2009). They are relatively a new way of harnessing energy that is gaining popularity at a quick pace. Small scale wind turbines on house roofs and retrofitting also fall under this category. The design of BUWTs is a complicated affair and involves the careful consideration of various factors. Since turbines are fixed into the building’s fabric its impact on the environment, building’s response and needs of its owners and occupants need to be weighed equally. Also numerous design decisions such as planning, structure, services, construction and maintenance depend on this single process (Stankovic S et al, 2009). With the increase in the scale of the proposal the importance of these factors increases simultaneously. The proposal generally spans from the number, scale, type and location of the turbines together with its annual energy yield and design life. A good BUWT based building should be a wholesome design that does not prejudice the buildings efficient functioning for energy generation. Generic options for BUWTs: Stankovic S et al (2009) explains that the wind turbines can be fixed on to a building in enumerable ways. Each method can accomplish a different level of power depending on the type of turbine used and the form of the building it is mounted upon. On top of a square/ rectangular building: This configuration is on the principle that the wind velocity increases with height and hence the amount of energy generated would be of a higher order (10% increase with wind acceleration). An added advantage is that the turbine would experience relatively little turbulence. But access to the turbine for maintenance and decommissioning works may be difficult. If mounted on tall buildings the turbines may threaten the visual quality of the skyline. On top of a rounded building: This case is very similar to the previous configuration except that with the use of rounded faà §ade the mean tower height can be considerably diminished. Also the rounded profile influences the local acceleration (15% increase in energy). The low tower height favors easy access to the turbine but leads to blade flicker and noise issues. Concentrator on top of a rounded building: This case is well suited to areas with bi-directional winds (20% energy increase over a free standing equivalent due to local acceleration). Vertical axis wind turbines are better suited for this feature while Horizontal axis wind turbines need to be suitably altered to achieve the same status. The building spaces that act as concentrators may be inhabited with suitable acoustical treatment. This case also encounters the same drawbacks as listed in the previous case. Square concentrator within a building faà §ade: As before, this configuration takes advantage of the higher quality winds at higher altitudes and local acceleration thereby achieving 25% increase in energy and 40% increase for bi-directional winds. This option is best suited for buildings with narrower profiles. There may be a loss in the saleable area of the building but the aperture can be converted into an exclusive feature such as a sky garden. The opening also relieves the wind loading on the building’s facade leading to simpler structural solutions. Vertical axis wind turbine is the only choice for integration due to its square swept area. Circular concentrator within a building faà §ade: This is very similar to the square concentrator except the opening is accustomed to hold pitch controlled horizontal axis wind turbines with fixed yaw. Also, a 35% increase for uniform wind and 50% increase in energy for bi-directional winds are achievable in this method. But on the down side, this technique is more expensive due to the cylindrical shroud. On the side of a building: In this technique, an increase in 80-90% in energy than the freestanding equivalents is achievable only if the building form is optimized to the local wind character. Only reliable vertical axis wind turbines can be used for power generation due to access issues. For higher swept area, more number of turbines should be used. Between multiple building forms: This type of an option opens out many doors for a range of architectural forms. Unlike the previous cases, the buildings orientation, form, shape and spacing play key roles in the performance of the turbines. Vertical axis wind turbines are better suited for this purpose. Guidelines for BUWT’s: The following are some guidelines outlined by Stankovic S et al (2009) for incorporating wind turbines into a structure: BUWTs should be tailored to the specific site for good results. Adequate wind resources should be available on site. If however if the site is under resourced steps are to be adopted to deliberately elevate the quality of the wind through the buildings form or turbine. The impact of its surroundings should also be considered before commissioning such a project. The dominating wind direction and its intensity should be observed from meteorological data. This would help in determining the form and orientation of the building together with finalizing the position of the wind turbine to make the most out of the available resource. Environmental impact assessment corresponding to the site should be carried out to foresee the adverse effects the turbines may create. Acoustic isolation may be sought for in some areas within the building if it lies at close proximity to the rotor. Natural ventilation and day lighting qualities of the building may be challenged and forced to settle for artificial means. The type and position of openings, external shading devices, smoke extracts etc should be handled with appropriate care to avoid draught winds. Access to the wind turbines for maintenance and decommissioning must be provided suitably. The aesthetic quality of the mounted turbines must harmonize with its surroundings and should not over power the pedestrians at ground level. To this end well suited screening devices such as canopies, screens and landscape may be utilized as per the necessity. The overall success of BUWT project depends on its ability to deliver the expected power. Inability to comply with this effect would result in the failure of its intended purpose from both an environmental and design point of view. Thus the electricity demand of the building and the level to which this would be met with should be estimated prior to turbine design to secure maximum benefits. Wind flow prediction and energy yields: For any project to be successful, Wind flow and building design (Taranath Bungale S, 2005) When the air moves in a vertical direction it is referred to as a current. These currents play a major role in meteorology whereas the gradual decrease in wind speed and high turbulence of the horizontal motion of air, at the ground level, are vital in building engineering. In urban areas, this zone of turbulence extends to a height of approximately one quarter of a mile aboveground and is called the surface boundary layer. Above this layer, the horizontal airflow is no longer influenced by the ground effect. The wind speed at this height is known as the gradient wind speed, and it is precisely in this boundary layer where most human activity is conducted. Characteristics of wind: The flow of wind is complex because many flow situations arise from the interaction of wind with structures. A few characteristics of wind include: Variation of wind velocity with height: The viscosity of air reduces its velocity adjacent to the earth’s surface to almost zero. A retarding effect occurs in the wind layers near the ground, and these layers in turn successively slow the outer layers. The slowing down is reduced at each layer as the height increases, and eventually becomes negligibly small. The height at which velocity ceases to increase is called the gradient height, and the corresponding velocity, the gradient velocity. At heights of approximately 366m aboveground, the wind speed is virtually unaffected by surface friction, and its movement is solely dependant on prevailing seasonal and local wind effects the height through which the wind speed is affected by topography is called the atmospheric boundary layer. Wind turbulence: Motion of wind is turbulent and it occurs in wind flow because air has a very low viscosity-about one-sixteenth that of water. Any movement of air at speeds greater than 0.9 to 1.3 m/s is turbulent, causing air particles to move randomly in all directions. Vortex shedding: In general, wind buffering against a bluff body such as a rectangular building gets diverted in three mutually perpendicular directions. However, only the longitudinal winds and the transverse winds or crosswinds are considered in civil engineering. When a free flowing mass of air encounters a building along its path, the originally parallel upwind streamlines are displaced on either side of the building. This results in spiral vortices being shed periodically from the sides into the downstream flow of the wind, called the wake. At relatively low wind speeds the vortices are shed, that is, break away from the surface of the building and an impulse is applied in the transverse direction. Distribution of pressures and suctions: When air flows around the edges of a structure, the resulting pressures at the corners are much in excess of the pressures on the center of elevation. This has been evident by the damages caused to corner windows, eave and ridge tiles, etc in windstorms. Wind tunnel studies conducted on scale models of buildings indicate that three distinct pressure areas develop around the building. They are: Positive pressure zone on the upstream face (Region 1) Negative pressure zone at the upstream corners (Region 2) Negative pressure zone on the downstream face (Region 3) The highest negative pressures are created in the upstream corners designated as Region 2. Wind pressures on a buildings surface are not constant, but fluctuate continuously. The positive pressure on the upstream or the windward face fluctuates more than the negative pressure on the downstream or the leeward face. The negative pressure region remains relatively steady as compared to the positive pressure zone. The fluctuation of pressure is random and varies from point to point on the building surface. Nearby buildings can have a significant influence on wind forces. If they are the same height as the structure being considered then they will mostly provide shelter, although local wind loads can be increased in some situations. Where surrounding buildings are significantly taller they will often generate increased wind loading (negative shelter) on nearby lower structures. Shelter can result from either from the general built-environment upwind of the site or from the direct shielding from specific individual upwind buildings (Blackmore P, 2004). Natural ventilation The three natural ventilation airflow paths in buildings are (Pennycook, 2009): Cross ventilation Single-sided ventilation Passive stack ventilation Advantages of cross ventilation: Greater rates of ventilation can be achieved under amicable weather conditions. Can be utilized for deep-plan spaces with operable windows on the external wall. Incumbents have control over ventilation. Relatively cost free. Can be incorporated with thermal masses. However, it has certain limitations such as: Internal space layout must be hindrance free for easy, clear flow of air. Internal partitions must be within 1.2m height and tall cupboards must be placed alongside the windows. Natural ventilation can occur only under the presence of suitable winds. Poor planning and positioning of windows may cause disruptive draughts and gusts. Winter ventilation is problematic. Unsuitable for buildings located in noisy and pollution prone environments. The requirements of fresh air supply are governed by the type of occupancy, number and activity of the occupants and by the nature of any processes carried out in the space (Koenigsberger et al, 2001). When natural ventilation is stipulated for good indoor air quality, the amount and nature of the dominant pollutant source in the space should be identified. Based on this data the ventilation rate for the space can be calculated such that the pollution level does not cross a preset specific mark. Generally the concentration of the pollutants decreases with the increase in airflow rate (Figure –1). However, in terms of thermal comfort especially during winter the heating requirement of the building will increase with the ventilation rate. This demand varies with time, wind characteristics of the place, opening and closing of windows and doors by its occupants and the thermal state of the building. In summer, cooling is ideal for both the building and its occupants to prevent internal heat gains. By directing the high velocity wind around the human body the evaporative rate at the skins surface can be increased thereby achieving a cooling sensation. The recommended upper limit of indoor air movement is 0.8 m/sec, which permits the inhabitants to occupy a space about 2 °C warmer and 60% relative humidity with optimum comfort. The traditional way to cool buildings is to provide large openings along the exterior wall with the principle that higher the ventilation rate greater the loss of heat to the external environment. But such an arrangement would work only when the outdoor te mperature is in the range of comfort zone. When controlled indoor environments are desired especially during the occupancy period’s night ventilation is recommended. In this technique the building is cooled at night so that it can absorb the heat generated during the day (Allard F, 1998). Based on wind tunnel experimental observations, the factors that affect the indoor airflow are: Orientation: External features: Cross-ventilation: Position of openings: Size of openings: Control of openings: Literature review The following are studies that have been made of different aspects of wind using Computational Fluid dynamics. CFD evaluation of wind speed conditions in passages between parallel buildings: This analysis undertaken by Blocken B et al (2007) mainly focuses on the wind speed conditions in passages between parallel buildings in combination with the accuracy of the commercial CFD code Fluent 6.1.22 when the wall-function roughness modifications are applied to them. The Venturi effect is also studied to determine the amount of increase in wind speed in the passage due to the decrease in flow section. The results obtained were compared with various previously proven experiments carried out by experts in the field. As the title indicated the case undertaken involves a pair of rectangular buildings measuring 40m x 20m x 20m, placed adjacent to each other and separated by a narrow passage. The width of the passage is widened (for example, 2, 4, 6, 8, 10, 15, 20, 30, 40, 60, 80, 100 m) with every case to clearly understand the Venturi effect. The dimension of the computational domain is 20.5x14x18m3; the whole setup is placed at a distance of 5m from the inlet and simulated with a wind speed of 6.8m/sec based on initial results. The results recorded at the end of the simulation process are discussed as follows. They are based on the amplification factor, which is defined as the ratio of the mean wind speed at a certain location to the mean wind speed at the same location without the buildings present. As such it is a direct indication of the effect of the buildings on the wind speed (Blocken B et al, 2007). Pedestrian level wind profile: In context to this research, for narrow passages (example w=2m) this amplification factor occurs maximum at the centerline immediately behind the entrance. When the distance between the buildings are slightly increased (example w=10m), the flow streams deflecting off the inner edges of the buildings combine into a large jet stream and records an increase in the amplification factor. However this property is lost when the width of the passage is of a high order (example w=30m). Overall wind profile: To understand the overall wind profile, six vertical lines were identified along the passage’s center plane for the case of w=6m. The lines depicted the fact that there was an increase in the wind speed at the ground level due to the downdraft of the wind along the front faà §ade of the building and a decrease in wind speed at the end of the passage due to the exit of flow from the passage. Also for these cases, there was no significant increase in the wind speed with the increase in height. Flow rates at different points in the passage: To evaluate the Venturi-effect three fluxes were defined, one along the vertical plane, another along the horizontal plan and the final being similar to the former one but in the absence of the buildings. When the flow rate was calculated for narrow passages, it stated an increase in wind speed by only 8% due to the Venturi effect. However for larger widths the flow rate was lower than the free-field flux. This shows that the wind has a tendency to flow over and around the building rather than be forced through the passage as previously believed. Thus there is a lack of strong Venturi effect and the flow in the passage can be attributed as the channeling effect for these cases. The research also concluded that there were discrepancies in the CFD results due to the use of the roughness factor and advised future users to simulate an empty field before positioning the buildings to clearly identify the difference in results. Further research into the Venturi effect was also implied. Computational analysis of wind driven natural ventilation in buildings: Evola G and Popov V (2006) research focuses on the application of three-dimensional Reynolds Averaged Navier-Strokes (RANS) modeling on wind driven natural ventilation with specific detail to the pressure distribution and flow pattern within the building. The various cases would be simulated with the standard k-e model and the Renormalization Group theory (RNG). Within the framework of natural ventilation both single sided ventilation and cross ventilation would be studied and the results obtained using CFD will be compared with LES models and empirical methods for its reliability.  Ã‚  Ã‚   The building undertaken consists of a 250mm x 250mm x 250mm cube punctured with a centrally located 84mm x 125 mm opening on the wind ward side (Case 1). In Case 2 the door like opening is placed on the leeward side and in Case 3 both the openings are retained to test the cross ventilation principle. On comparison between the CFD results obtained for Case 1 and 2, Case 2 portrays a better flow pattern especially at the mouth of the opening. This leads to a better ventilation rate than Case 1 though in contrast to the theoretical data that good ventilation rate and flow patterns are achievable only when the opening faces the incoming winds. To establish the phenomenon further experimentation into the field was suggested. Between Cases 1, 2 and 3, cross ventilation clearly stands out as the best option of them all, both in terms of velocity and distribution. Also the study concluded that the measured RNG results matched approximately to the theoretical results of Cases 1 and 2. But a significant amount of deviation was observed in Case 3. The RNG model was only slightly intense than the k-e model generally used. The research also concluded that there were discrepancies in the CFD results due to the use of the roughness factor and advised future users to simulate an empty field before positioning the buildings to clearly identify the difference in results. Further research into the Venturi effect was also implied. CFD modeling of unsteady cross-ventilation flows using LES: This research undertaken by Cheng-Hu Hu et al (2008) employs the LES method to investigate the fluctuating ventilation flow rate induced by the wind for a cross-ventilated building. The results from CFD were compared with those previously acquired from wind tunnel tests.   Ã‚   The building proposed for the study consists of a rectangular box with two openings of equal size located opposite to each other. The wind is simulated from 0 °(Case 1) and 90 °(Case 2) to the building at a rate of 1m/sec, to study the flow pattern in and around it. When the air approaches the building the ventilation rate is unsteady at the mouth of the openings due to turbulence and in the flow separation layer due to shear. In Case 1 the wind is accelerated through the opening and directed downwards inside the building. This phenomenon brings about a circulation of the internal air before guiding the wind upwards and out through the window on the leeward side of the building. The air exchange occurs due to the mean flows through the opening. In Case 2 where the wind is parallel to the windows, the air moves in and exits rapidly causing fluctuating flows thereby leading to air exchange. In this case turbulence prone areas are formed at the rear of the building. When these results were compared with the wind tunnel data, Case 1 portrayed similarities while Case 2 had major deviations. Further study was proposed for understanding the reason behind such deviations. Case studies The Bahrain world trade centre was the world’s first building to ‘aesthetically incorporate commercial wind turbines into the fabric of the building’ [ ]. The complex consists of a three-storied sculpted podium and basement from where the 240m high towers rise up into the sky. The two towers comprise of 51 floors each and are connected by means of three, 31.5m span bridges at 60m, 96m and 132m levels [ ]. They are oval in section for aerodynamic reasons and follow a shallow V-shape in plan for adequate blade clearance. Sitting on each of this 70 ton spandrel is an 11-ton nacelle to which the industry approved horizontal axis wind turbines are fixed by special means. The turbine has a rotor diameter of 29m and is stall controlled with centrifugally activated feathering tips for air brakes (Killa S Smith Richard F, 2008). The turbines are oriented facing the Arabian Gulf intercepting the path of the dominant winds. The decision to harness the prevailing wind was thought of from the initial stage drawing inspiration from ‘the regional wind towers and the vast sails of the traditional Arabian Dhow which utilise the wind to drive them forward’. Numerous Computational fluid dynamics models and wind tunnel tests were carried out to determine the final building form. The result was a skyward tapering, elliptical structure, carved out by the wind that functions as aerofoil sections (Wood A, 2008). The shape and spatial relationship of the towers aid in adhering the wind in a â€Å"S’ flow whereby the center of the wind stream remains nearly perpendicular to the turbine within a 45 ° wind azimuth, either side of the central axis (Killa S Smith Richard F, 2008). This increases the turbine efficiency, number of working hours and minimizes the stress on the blade caused by yawing [ ]. Furthermore, the two towers were placed such that they create a ‘V’ shaped space in between them, as well as a negative pressure behind the blocks, thus creating an opportunity for the Venturi effect to accelerate wind velocity onto the turbines (Binder G, 2006) by as much as 30% more than the source wind (Killa S Smith Richard F, 2008). The tapering profile combined with the increased onshore wind velocity at higher altitudes creates a near equal regime of wind speed on each of the three turbines, irrespective of its location, allowing them to rotate at the same speed and generate approximately the same amount of energy (Wood A, 2008). Table 1: Annual energy output