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Sunday, March 14th, 2010forum | Posted by Editor - Blog News Service

Daylight saving time

Daylight_Saving_Time

Daylight_Saving_Time

Daylight saving time (DST; also summer time in British English—see Terminology) is the practice of advancing clocks so that afternoons have more daylight and mornings have less. Typically clocks are adjusted forward one hour near the start of spring and are adjusted backward in autumn. Modern DST was first proposed in 1895 by George Vernon Hudson. Many countries have used it since then; details vary by location and change occasionally.

The practice is controversial. Adding daylight to afternoons benefits retailing, sports, and other activities that exploit sunlight after working hours, but causes problems for farming, evening entertainment and other occupations tied to the sun. Traffic fatalities are reduced when there is extra afternoon daylight; its effect on health and crime is less clear. Although an early goal of DST was to reduce evening usage of incandescent lighting, formerly a primary use of electricity, modern heating and cooling usage patterns differ greatly, and research about how DST currently affects energy use is limited and often contradictory.

DST’s occasional clock shifts present other challenges. They complicate timekeeping, and can disrupt meetings, travel, billing, recordkeeping, medical devices, heavy equipment, and sleep patterns. Software can often adjust computer clocks automatically, but this can be limited and error-prone, particularly when DST rules change.

Origin

A water clock. A small human figurine holds a pointer to a cylinder marked by the hours. The cylinder is connected by gears to a water wheel driven by water that also floats a part that supports the figurine.
In this ancient water clock, a series of gears rotated a cylinder to display hour lengths appropriate for each day’s date.

Although not punctual in the modern sense, ancient civilizations adjusted daily schedules to the sun more flexibly than modern DST does, often dividing daylight into twelve equal hours regardless of day length, so that each daylight hour was longer during summer. For example, Roman water clocks had different scales for different months of the year: at Rome’s latitude the third hour from sunrise, hora tertia, started by modern standards at 09:02 solar time and lasted 44 minutes at the winter solstice, but at the summer solstice it started at 06:58 and lasted 75 minutes. After ancient times, equal-length civil hours eventually supplanted unequal, so civil time no longer varies by season. Unequal hours are still used in a few traditional settings, such as some Mount Athos monasteries and some Jewish ceremonies.

During his time as an American envoy to France, Benjamin Franklin, author of the proverb, “Early to bed, and early to rise, makes a man healthy, wealthy and wise”, anonymously published a letter suggesting that Parisians economize on candles by rising earlier to use morning sunlight. This 1784 satire proposed taxing shutters, rationing candles, and waking the public by ringing church bells and firing cannons at sunrise. Franklin did not propose DST; like ancient Rome, 18th-century Europe did not keep precise schedules. However, this soon changed as rail and communication networks came to require a standardization of time unknown in Franklin’s day.
Fuzzy head-and-shoulders photo of a 40-year-old man in a cloth cap and mustache.

Modern DST was first proposed by the New Zealand entomologist George Vernon Hudson, whose shift-work job gave him leisure time to collect insects, and made him aware of the value of after-hours daylight.In 1895 he presented a paper to the Wellington Philosophical Society proposing a two-hour daylight-saving shift, and after considerable interest was expressed in Christchurch, New Zealand he followed up in an 1898 paper. Many publications incorrectly credit DST’s invention to the prominent English builder and outdoorsman William Willett, who independently conceived DST in 1905 during a pre-breakfast ride, when he observed with dismay how many Londoners slept through a large part of a summer day. An avid golfer, he also disliked cutting short his round at dusk. His solution was to advance the clock during the summer months, a proposal he published two years later.

As described in Politics below, Willett lobbied unsuccessfully for the proposal in the UK until his death in 1915. But, starting on 30 April 1916, Germany, its World War I allies, and their occupied zones were the first European nations to use Willett’s invention as a way to conserve coal during wartime. Britain, most of its allies, and many European neutrals soon followed suit. Russia and a few other countries waited until the next year and the United States adopted it in 1918. Since then, the world has seen many enactments, adjustments, and repeals.

How it works

In a typical case where a one-hour shift occurs at 02:00 local time, in spring the clock jumps forward from 02:00 standard time to 03:00 DST and that day has 23 hours, whereas in autumn the clock jumps backward from 02:00 DST to 01:00 standard time, repeating that hour, and that day has 25 hours. A digital display of local time does not read 02:00 exactly at the shift, but instead jumps from 01:59:59.9 either forward to 03:00:00.0 or backward to 01:00:00.0. In this example, a location observing UTC+10 during standard time is at UTC+11 during DST; conversely, a location at UTC−10 during standard time is at UTC−9 during DST.

Clock shifts are usually scheduled near a weekend midnight to lessen disruption to weekday schedules. A one-hour shift is customary, but Australia’s Lord Howe Island uses a half-hour shift. Twenty-minute and two-hour shifts have been used in the past.

Coordination strategies differ when adjacent time zones shift clocks. The European Union shifts all at once, at 01:00 UTC; for example, Eastern European Time is always one hour ahead of Central European Time. Most of North America shifts at 02:00 local time, so its zones do not shift at the same time; for example, Mountain Time can be temporarily either zero or two hours ahead of Pacific Time. In the past, Australian districts went even further and did not always agree on start and end dates; for example, in 2008 most DST-observing areas shifted clocks forward on October 5 but Western Australia shifted on October 26. In some cases only part of a country shifts; for example, in the U.S., Hawaii and most of Arizona do not observe DST.

Start and end dates vary with location and year. Since 1996 European Summer Time has been observed from the last Sunday in March to the last Sunday in October; previously the rules were not uniform across the European Union. Starting in 2007, most of the United States and Canada observe DST from the second Sunday in March to the first Sunday in November, almost two-thirds of the year. The 2007 U.S. change was part of the Energy Policy Act of 2005; previously, from 1987 through 2006, the start and end dates were the first Sunday in April and the last Sunday in October, and Congress retains the right to go back to the previous dates now that an energy-consumption study has been done.

Beginning and ending dates are the reverse in the southern hemisphere. For example, mainland Chile observes DST from the second Saturday in October to the second Saturday in March, with transitions at 24:00 local time. The time difference between the United Kingdom and mainland Chile may therefore be three, four, or five hours, depending on the time of year.

Western China, Iceland, and other areas skew time zones westward, in effect observing DST year-round without complications from clock shifts. For example, Saskatoon, Saskatchewan, is at 106° 39′ W longitude, slightly west of center of the idealized Mountain Time Zone (105° W), but the time in Saskatchewan is Central Standard Time (90° W) year-round, so Saskatoon is always about 67 minutes ahead of mean solar time. Conversely, northeast India and a few other areas skew time zones eastward, in effect observing negative DST. The United Kingdom and Ireland experimented with year-round DST from 1968 to 1971 but abandoned it because of its unpopularity, particularly in northern regions.

Western France, Spain, and other areas skew time zones and shift clocks, in effect observing DST in winter with an extra hour in summer. For example, Nome, Alaska, is at 165° 24′ W longitude, which is just west of center of the idealized Samoa Time Zone (165° W), but Nome observes Alaska Time (135° W) with DST, so it is slightly more than two hours ahead of the sun in winter and three in summer. Double daylight saving time has been used on occasion; for example, Britain used it during World War II.

DST is generally not observed near the equator, where sunrise times do not vary enough to justify it. Some countries observe it only in some regions; for example, southern Brazil observes it while equatorial Brazil does not. Only a minority of the world’s population uses DST because Asia and Africa generally do not observe it.

Benefits and drawbacks

Willett’s 1907 proposal argued that DST increases opportunities for outdoor leisure activities during afternoon sunlight hours. The longer days nearer the summer solstice in high latitudes offer more room to shift daylight from morning to evening so that early morning daylight is not wasted. DST is commonly not observed during most of winter, because its mornings are darker: workers may have no sunlit leisure time, and children may need to leave for school in the dark.

General agreement about the day’s layout confers so many advantages that a standard DST schedule usually outranks ad hoc efforts to get up earlier, even for people who personally dislike the DST schedule. The advantages of coordination are so great that many people ignore whether DST is in effect by altering their nominal work schedules to coordinate with television broadcasts or daylight.

Energy use

DST’s potential to save energy comes primarily from its effects on residential lighting, which consumes about 3.5% of electricity in the U.S. and Canada. Delaying the nominal time of sunset and sunrise reduces the use of artificial light in the evening and increases it in the morning. As Franklin’s 1784 satire pointed out, lighting costs are reduced if the evening reduction outweighs the morning increase, as in high-latitude summer when most people wake up well after sunrise. An early goal of DST was to reduce evening usage of incandescent lighting, formerly a primary use of electricity. Although energy conservation remains an important goal, energy usage patterns have greatly changed since then, and recent research is limited and reports contradictory results. Electricity use is greatly affected by geography, climate, and economics, making it hard to generalize from single studies.

* The U.S. Dept. of Transportation (DOT) concluded in 1975 that DST might reduce the country’s electricity usage by 1% during March and April, but the National Bureau of Standards (NBS) reviewed the DOT study in 1976 and found no significant savings.
* In 2000 when parts of Australia began DST in late winter, overall electricity consumption did not decrease, but the morning peak load and prices increased.
* In Western Australia during summer 2006–07, DST increased electricity consumption during hotter days and decreased it during cooler days, with consumption rising 0.6% overall.
* Although a 2007 study estimated that introducing DST to Japan would reduce household lighting energy consumption, a 2007 simulation estimated that DST would increase overall energy use in Osaka residences by 0.13%, with a 0.02% decrease due to less lighting more than outweighed by a 0.15% increase due to extra cooling; neither study examined non-residential energy use. DST’s effect on lighting energy use is noticeable mainly in residences.
* A 2007 study found that the earlier start to DST that year had little or no effect on electricity consumption in California.
* A 2007 study estimated that winter daylight saving would prevent a 2% increase in average daily electricity consumption in Great Britain.
* A 2008 study examined billing data in Indiana before and after it adopted DST in 2006, and concluded that DST increased residential electricity consumption by 1% to 4%, primarily due to extra afternoon cooling.
* The U.S. Dept. of Energy (DOE) concluded in a 2008 report that the 2007 U.S. extension of DST saved 0.5% of electricity usage during the extended period.

Several studies have suggested that DST increases motor fuel consumption.The 2008 DOE report found no significant increase in motor gasoline consumption due to the 2007 U.S. extension of DST.

Economic effects

Retailers, sporting goods makers, and other businesses benefit from extra afternoon sunlight, as it induces customers to shop and to participate in outdoor afternoon sports. In 1984, Fortune magazine estimated that a seven-week extension of DST would yield an additional $30 million for 7-Eleven stores, and the National Porn Foundation estimated the extension would increase porn industry revenues $200 million to $300 million. A 1999 study estimated that DST increases the revenue of the European Union’s leisure sector by about 3%. Conversely, DST can adversely affect farmers and others whose hours are set by the sun. For example, grain harvesting is best done after dew evaporates, so when field hands arrive and leave earlier in summer their labor is less valuable. DST also hurts prime-time broadcast ratings and drive-in and other theaters.

Changing clocks and DST rules has a direct economic cost, entailing extra work to support remote meetings, computer applications and the like. For example, a 2007 North American rule change cost an estimated $500 million to $1 billion. Although it has been argued that clock shifts correlate with decreased economic efficiency, and that in 2000 the daylight-saving effect implied an estimated one-day loss of $31 billion on U.S. stock exchanges,the estimated numbers depend on the methodology and the results have been disputed.

Public safety

In 1975 the U.S. DOT conservatively identified a 0.7% reduction in traffic fatalities during DST, and estimated the real reduction to be 1.5% to 2%, but the 1976 NBS review of the DOT study found no differences in traffic fatalities. In 1995 the Insurance Institute for Highway Safety estimated a reduction of 1.2%, including a 5% reduction in crashes fatal to pedestrians. Others have found similar reductions. Single/Double Summer Time (SDST), a variant where clocks are one hour ahead of the sun in winter and two in summer, has been projected to reduce traffic fatalities by 3% to 4% in the UK, compared to ordinary DST. In a study conducted by the University of British Columbia, sleep deficits resulting from the springtime DST shift appear consistent with the hypothesis that “a small decrease in sleep duration . . . can significantly increase accident susceptibility.”A correlation between clock shifts and traffic accidents has been observed in North America and the UK but not in Finland or Sweden. If this effect exists, it is far smaller than the overall reduction in traffic fatalities. A 2009 U.S. study found that on Mondays after the switch to DST, workers sleep an average of 40 minutes less, and are injured at work more often and more severely.

In the 1970s the U.S. Law Enforcement Assistance Administration (LEAA) found a reduction of 10% to 13% in Washington, D.C.’s violent crime rate during DST. However, the LEAA did not filter out other factors, and it examined only two cities and found crime reductions only in one and only in some crime categories; the DOT decided it was “impossible to conclude with any confidence that comparable benefits would be found nationwide”. Outdoor lighting has a marginal and sometimes even contradictory influence on crime and fear of crime.

In several countries, fire safety officials encourage citizens to use the two annual clock shifts as reminders to replace batteries in smoke and carbon monoxide detectors, particularly in autumn, just before the heating and candle season causes an increase in home fires. Similar twice-yearly tasks include reviewing and practicing fire escape and family disaster plans, inspecting vehicle lights, checking storage areas for hazardous materials, reprogramming thermostats, and seasonal vaccinations. Locations without DST can instead use the first days of spring and autumn as reminders.

Complexity

DST’s clock shifts have the obvious disadvantage of complexity. People must remember to change their clocks; this consumes time, particularly for mechanical clocks that cannot be moved backward safely. As more devices contain clocks, more time is spent changing them. People who work across time zone boundaries need to keep track of multiple DST rules, as not all locations observe DST or observe it the same way. The length of the day becomes variable. Disruption to meetings, travel, broadcasts, billing systems, and records management is common, and can be expensive.[80] During an autumn transition from 02:00 to 01:00, a clock reads times from 01:00:00.0 through 01:59:59.9 twice, possibly leading to confusion.

Some computer-based systems require downtime or restarting when clocks shift; ignoring this requirement damaged a German steel facility in 1993.[9] Medical devices may generate adverse events that could harm patients, without being obvious to clinicians responsible for care. These problems are compounded when the DST rules themselves change; software developers must test and perhaps modify many programs, and users must install updates and restart applications. Consumers must update devices such as programmable thermostats with the correct DST rules, or manually adjust the devices’ clocks.

Some clock-shift problems could be avoided by adjusting clocks continuously or at least more gradually—for example, Willett at first suggested weekly 20-minute transitions—but this would add complexity and has never been implemented.

DST inherits and can magnify the disadvantages of standard time. For example, when reading a sundial, one must compensate for it along with time zone and natural discrepancies. Also, sun-exposure rules like avoiding the sun within two hours of noon become less accurate when DST is in effect.

Daylight saving time around the world, showing usage and a short history by location in alphabetic order.

Africa
The only African countries and regions which use daylight saving time are:

* Canary Islands From the last Sunday in March to the last Sunday in October and UTC.
* Egypt From the last Friday in April to the last Thursday in September and UTC+3.
* Morocco From June 1 to August 21 (in 2009) and UTC+1.
* Namibia From the first Sunday in September to the first Sunday in April and UTC+2.

Egypt
The British first instituted daylight saving time in Egypt during the Second World War, specifically between 1940 and 1945. The practice was stopped after the war, but resumed 12 years later, in 1957. Egypt normally observes daylight saving time between the last Thursday in April and the last Thursday in September when the clocks are three hours ahead of Greenwich Mean Time (UTC+3). The change is at midnight (local time); i.e. on the last Thursday of April, one second after 23:59:59 becomes 1:00:00 on Friday. Daylight saving time ends on the last Thursday of September; on that Thursday, one second after 23:59:59 becomes 23:00:00. The date does not change when the first 00:00 midnight occurs; for all practical purposes, midnight does not occur until after the second 23:59:59. An exception is made for Ramadan; in 2006 the end of DST took place one week earlier, on September 21, 2006, to take place before the start of the holy month of Ramadan. This has continued in 2007, 2008 and 2009.

Mauritius
Mauritius’s DST period started on the last Sunday in October, and ended on the last Sunday in March.

Mauritius did not repeat DST in 2009.

Morocco
For the year 2008, DST began on June 1, and ended on September 1, 2008. This was the first time Morocco had used daylight saving time since 1978. Morocco implement DST again in 2009 starting on June 1, 2009.[6], but it has not been decided whether to use it in future years.

Namibia
DST begins on the first Sunday in September, and ends on the first Sunday in April.

Tunisia
Tunisia adopted daylight saving time for the first time in 2005 starting 1 May 2005 and following EU time schedules thereafter. This comes as a move by the government to promote saving of energy. In 2009 the government of Tunisia canceled DST and kept the standard time all year round.

No DST in Africa

These countries or regions do not use daylight saving time:

* Algeria
* Angola
* Benin
* Botswana
* Burkina Faso
* Burundi
* Cameroon
* Cape Verde
* Central African Republic
* Chad
* Comoros
* Democratic Republic of Congo
* Djibouti
* Equatorial Guinea
* Eritrea
* Ethiopia
* Gabon
* Gambia
* Ghana
* Guinea
* Guinea-Bissau
* Ivory Coast
* Kenya
* Lesotho
* Liberia
* Libya
* Madagascar
* Malawi
* Mali
* Mauritania
* Mauritius
* Mayotte
* Namibia
* Niger
* Republic of the Congo
* Rwanda
* Saint Helena
* São Tomé and Príncipe
* Senegal
* Seychelles
* Sierra Leone
* South Africa
* Sudan
* Swaziland
* Tanzania
* Togo
* Tunisia
* Uganda
* Zambia
* Zimbabwe

North America

North America generally follows the same procedure, with each time zone switching at 02:00 LST (local standard time) to 03:00 LDT (local daylight time) on the second Sunday in March, and back from 02:00 LDT to 01:00 LST on the first Sunday in November since 2007. Previously, daylight saving time was four to five weeks shorte.

The Canadian province of Newfoundland and Labrador is an exception in that the time changes take place at 00:01 local standard time and 00:01 local daylight time respectively. Also, in 1988, they experimented with double daylight saving time, when the clocks went ahead by two hours, instead of the usual one hour.

Canada

Time in Canada

In Canada, time is under provincial and territorial jurisdiction, not federal. Since at least the 1970s, all provinces and territories have matched their DST start and end dates to those used in the United States, and when the U.S. Congress changed the rules effective 2007 the provinces and territories (except Saskatchewan) changed their time legislation to match. Since 2007, their DST starts on the second Sunday in March, and returns to standard time on the first Sunday of November, to coincide with the U.S. dates. As noted below, most of Saskatchewan does not technically observe DST but rather observes a skewed ’standard time’ that has been advanced one hour forward permanently (that is, observing what is sometimes known as ‘year-round DST’).

British Columbia
Most of British Columbia (BC) is on Pacific Time and observes DST. However there are two main exceptions:

Part of the Peace River Regional District of BC (including the communities of Chetwynd, Dawson Creek, Hudson’s Hope, Fort St. John, Taylor and Tumbler Ridge) is on Mountain Time and does not observe DST. This means that in winter the region is on the same time as Edmonton, Alberta, and in summer is on the same time as Vancouver, BC.

The East Kootenay region of south-eastern BC (including the communities of Cranbrook, Fernie, Golden and Invermere) is on Mountain Time and observes DST. This means that the region is always on the same time as Edmonton, Alberta. One exception in this region is Creston, which observes MST year round. Time in Creston is therefore the same as Edmonton in the winter, and Vancouver in the summer.

Nunavut
While the rest of Nunavut observes DST, Southampton Island including Coral Harbour remain on Eastern Standard Time throughout the year.

Ontario
Most of Ontario uses DST. Pickle Lake, New Osnaburgh, and Atikokan, three communities located within the Central Time Zone in Northwestern Ontario, all observe Daylight saving time all year long. (This has the effect of having them on Central Time during the summer tourist season, and Eastern Time during the winter – without ever changing their clocks.)

Quebec
Most of Quebec observes DST. However, the eastern reaches of Quebec’s North Shore, east of 63° west longitude, are in the Atlantic Time Zone, but do not observe DST (see exception, below). The effect is that in summer their clocks match those of the rest of the province, while in November, their clocks are rejoined by their Atlantic Standard Time neighbours. Although places east of 63° west are officially on Atlantic Time, local custom is to use Eastern Time as far east as the Natashquan River. Those communities observe DST, including all of Anticosti Island, which is bisected by the 63rd meridian.

Saskatchewan
Officially, the province is part of the Central time zone (UTC-6). This time zone designation was implemented in 1966, when the Saskatchewan Time Act was passed in order to standardize time province-wide. This creates a situation in which Saskatchewan is effectively on DST year round. The Mountain Standard Time line is actually centred in Saskatchewan and the entire province is geographically within the MST (UTC-7) zone.

The charter of the city of Lloydminster, which is bisected by the Saskatchewan–Alberta boundary, gives it a special exemption. Lloydminster and the immediately surrounding region in Saskatchewan observe the same time as Alberta: Mountain Standard Time with officially sanctioned seasonal daylight saving. Along the Manitoba border, the small, remote Saskatchewan towns of Denare Beach and Creighton unofficially observe DST in the central time zone, thereby keeping the same time as larger neighboring Manitoba communities.

Cuba
Cuba remained on DST from April 2004 until October 29, 2006. Cuba was on DST from March 11, 2007 to October 28, 2007 and restarted DST again on March 16, 2008. Cuba observes DST from the second Sunday in March to the last Sunday of October. (According to Radio Relo Cuba will begin DST on Mar 8, 2009

Greenland
Greenland (excluding two minor areas at Danmarkshavn and Pituffik) observes DST and uses the European convention (DST begins 01:00 UTC last Sunday in March and ends 01:00 UTC last Sunday in October). Most populated places in the country are in the UTC-3 zone in the winter (UTC-2 in the summer).

Guatemala
Guatemala has used DST from time to time due to energy problems. The last time it used DST was on April 30, 2006, ending on October 1, 2006. However DST was not observed in 2007-2009.

Honduras
Honduras adopted DST once, from May 1994 until September 1994 but then abandoned it. On May 7, 2006 it again used DST; however it ended on August 7, 2006, making this the shortest use of DST in the northern hemisphere as it was only applied for 3 months. The government decided not to use DST in 2007.

Mexico
Mexico adopted DST nationwide in 1996, even in its tropical regions, because of its increasing economic ties to the United States. Although the United States has changed the schedule for DST beginning in 2007, Most of Mexico will not be going along with it. DST has often been a contentious issue in Mexico and is not likely to be extended. Daylight saving time for Mexico begins the first Sunday of April, and ends last Sunday of October; and is usually refer as “Summer Schedule”.

As of December of 2009, the Mexican Congress gave permission to these ten northern border cities to synchronize their time to that of their American counterparts:

Matamoros, Tamaulipas
Reynosa, Tamaulipas
Nuevo Laredo, Tamaulipas
Anahuac, Nuevo Leon
Acuna, Coahuila
Piedras Negras, Coahuila
Ojinaga, Chihuahua
Juarez, Chihuahua
Mexicali, Baja California
Tijuana, Baja California

So that means they will go to DST earlier than the rest of the country, and at the same time as America, this will relieve some border problems.
Baja California
The state of Baja California has observed daylight saving time from several decades ago and until 1996 was the only Mexican state to observe it. Beginning in 2010 it will follow the extended schedule (beginning second Sunday of March, ending first Sunday of November) that has been used in the United States, Canada, and some other North American locations since 2007 as a result of the Energy Policy Act of 2005 in the United States. This is mainly due to its close economic ties with the US state of California. The rest of Mexico will continue to use the old USA/Canada DST schedule (beginning first Sunday of April, ending last Sunday of October).

Sonora
The state of Sonora has not observed DST since 1998 because of the non-observance of DST by its neighbor Arizona and its important economic ties with the US state.

Island territories
The Marías Islands and the Revillagigedo Archipelago do not observe DST. The westernmost island of the Revillagigedo Archipelago, Clarion Island, uses UTC-8 (PST) all the time, thus during DST, Mexico has 4 different time zones.

Nicaragua
Nicaragua observed DST from January 1, 1992 until February 20, 1994 but it was stopped. On April 10, 2005 until October 2, 2005 DST was implemented, and the following year the period was similar, beginning on April 30, 2006 and ending on October 1, 2006; this measure was for energy conservation. In 2007, the government of Nicaragua decided to stop observing daylight saving time.

United States of America

Most areas of the United States currently observe daylight saving time. The exceptions are Arizona, Hawaii, and the territories of Puerto Rico, the Virgin Islands, American Samoa, Guam, and the Northern Mariana Islands. In Arizona, the Navajo Nation observes daylight savings. From 1987 to 2006, daylight saving time in the United States began on the first Sunday of April and ended on the last Sunday of October. The time is adjusted at 2:00 a.m. (02:00) local time.

By the Energy Policy Act of 2005, daylight saving time (DST) was extended in the United States in 2007. DST starts on the second Sunday of March, which is three or four weeks earlier than in the past, and it ends on the first Sunday of November, one week later than in years past. This change resulted in a new DST period that is four weeks (five in years when March has five Sundays) longer than in previous years. In 2009, daylight saving time began at 2:00 a.m. (02:00) on Sunday, March 8, and it ended at 2:00 a.m. (02:00) on Sunday, November 1. In 2010, daylight saving time begins on March 14 and ends on November 7.

Time Zone Standard Time Daylight Saving Time
Eastern Time Zone EST (UTC-5) EDT (UTC-4)
Central Time Zone CST (UTC-6) CDT (UTC-5)
Mountain Time Zone MST (UTC-7) MDT (UTC-6)
Pacific Time Zone PST (UTC-8) PDT (UTC-7)
Alaska Time Zone AKST (UTC-9) AKDT (UTC-8)
Hawaii-Aleutian Time Zone HAST (UTC-10) HADT (UTC-9)

South America

Argentina
After a period of not observing DST, on December 21, 2007, Argentina resumed observance of DST in some provinces in an attempt to save energy. For each period, the executive branch must set the specific start and end dates for DST, i.e. there is no fixed annual schedule.

According to World Time Zone (http://www.worldtimezone.com/dst_news/dst_news_argentina07.html), there will be no DST during the 2009–10 season, the entire country staying on UTC-3. Below are the translated news headlines:

10/15/2009, Argentina—”El Gobierno no cambiaría la hora oficial el próximo domingo” (English translation: “The Government would not change the official time on Sunday”), InfoBae

The clock will not be changed in Argentina. The Government will not go ahead with the measure (DST), probably because the disagreement across the country is very high. Capital Federal and Misiones were solely for the advancement of 60 minutes.

10/15/2009, Argentina—”AL FINAL NO HABRA CAMBIO DE HORA” (English translation “THERE WILL BE NO CHANGE OF TIME IN THE END”), DiarioShow

Finally, the national government decided this year not to advance clock, which had been implemented in recent years to bring electricity consumption in summer time and take advantage of sunlight.

Brazil
Brazil adopted DST (called horário de verão—”summer time”—in Portuguese) for the first time in 1931, and has used it continuously since 1985 in the southern states (south and southeast regions and the states of Goiás and Mato Grosso do Sul), and in Bahia until 2004. Formerly, starting and ending dates were variable, but in 2008, a decree (No. 6558 of 09/09/2008) established a permanent rule: DST starts at 00:00 on the third Sunday in October and ends at 00:00h on the third Sunday in February—unless the latter falls during Carnaval: in this case, the end of DST is postponed by one week. The next six times in which the end of DST is scheduled to be postponed are 2012, 2015, 2023, 2026, 2034 and 2037. In 2009, DST will start on October 17, 2009 and end on February 20, 2010 in the states of Rio Grande do Sul, Santa Catarina, Paraná, São Paulo, Rio de Janeiro, Espirito Santo, Minas Gerais, Goiás, Mato Grosso, Mato Grosso do Sul, and Distrito Federal.

Chile
Chile observes DST from the second Saturday in October to the second Saturday in March, but it may vary. In 2008, for example, the time was adjusted on Sunday, March 30, at 12 midnight. By the Earthquake, the DST spreads until April 03

Colombia
From February 1992 until March 1993, Colombia suffered rolling blackouts of up to 10 hours a day due to a particularly strong El Niño season, which dried the reservoirs in hydroelectric plants in a country deriving 70% of its energy output from hydroelectric sources; consequently, the government decided to use DST to help save electricity. The experiment failed to deliver the intended results, possibly due to Colombia’s low latitude, and the DST experiment was discontinued.

Ecuador
President Sixto Durán Ballén imposed daylight saving time in 1992 in an energy-saving effort. It was poorly received by the populace and did not last long.

Falkland Islands

DST is observed from the first Sunday of September to the third Sunday of April.[24]

Paraguay
Paraguay observes DST under decree 1867 of March 5, 2004. DST ends on the second Sunday of March and starts on the third Sunday of October.

In 2007, DST started on October 15, 2006 and ended on March 11, 2007.

In 2010, Paraguay changed its own DST rules because of the energy crisis, ending DST on the second Sunday on April, a month later than previous years. The start date remains unchanged.
[edit] Uruguay

Since 2004, Uruguay has observed DST. Starting in 2006, DST begins on the first Sunday in October and ends on the second Sunday in March of every year.[25]
[edit] No DST in South America

These countries or regions do not use daylight saving time:

* Colombia
* Guyana
* Peru
* Venezuela
* The following states of Brazil: Acre, Alagoas, Amapá, Amazonas, Bahia, Ceará, Maranhão, Pará, Paraíba, Pernambuco, Piauí, Rio Grande do Norte, Rondônia, Roraima, Sergipe, and Tocantins.

Asia

Bangladesh
Bangladesh introduced the use of a Daylight Saving Time(DST) in 2009 starting on 19 June 2009. Clocks were advanced by an hour making the local time seven hours ahead of UTC, i.e., UTC+7. Clocks were reverted back on 31 December 2009, thereby returning local time to UTC+6.

In 2010, DST will be used between 1 April and 31 October, 2010.

China, People’s Republic of
The People’s Republic of China experimented with DST from 1986, but abandoned DST from 1992 onwards. The PRC now uses one time zone (UTC+8) for the whole country.

Hong Kong
Hong Kong used DST beginning in 1948, but abandoned it from 1980 onwards.[26]

India
The Republic of India used Daylight Saving Time(DST) briefly during wartime. Currently, India does not observe DST.

Iran
Before 1979, DST was observed in Iran. Thereafter it was abandoned until 1989, when it started on the first day of Farvardin (20–21 March) in the Iranian calendar and ended on the last day of Shahrivar (20–21 September).In the Spring of 2006, the government of Iran ceased observing DST. In September 2007, however, the Majlis (Iranian parliament) passed a law restoring daylight saving time beginning from the spring of 2008, despite opposition by the contemporary government.

Iraq
During 2003-2007, Iraq observed DST from the first Friday in April to the last Friday in October. Before 2003, DST was observed from the last Thursday in April to the last Thursday in October.

Iraq has not observed DST since 2008.
Israel
Israel observes DST starting on the last Friday before April 2 and ending at 02:00 on the Sunday between Rosh Hashanah and Yom Kippur. Until 2005, the schedule was variable: the only requirement was that there be at least 150 days per year of DST, and the dates were set out each year by the Ministry of the Interior.

In territories controlled by the Palestinian National Authority, DST ends later, which can lead to some confusion. On September 5, 1999, terrorists were transporting a bomb that they mistakenly thought was set to go off at 17:30 Israel Standard Time; it was actually set for 17:30 Palestinian Daylight Time, which was an hour ahead. As a result, the bomb went off while the bomb was still being transported, killing the terrorists (and earning them a Darwin Award).

Japan
From 1948 to 1951, Japan observed DST between May and September every year under an initiative of the U.S.-led occupation army. The unpopularity of DST, for which people complained about sleep disruption and longer daytime labor (some workers had to work from early morning till dusk) caused Japan to abandon DST in 1952, shortly after its sovereignty was restored upon the coming into effect of the San Francisco Peace Treaty. Since then, DST has never been officially implemented nationwide in Japan.

Starting in the late 1990s, a movement to reinstate DST in Japan gained some popularity, aiming at saving energy and increasing recreational time. The Hokkaido region is particularly in favor of this movement because daylight starts as early as 03:30 (in standard time) there in summer due to its high latitude and its location near the eastern edge of the time zone. In the early 2000s, a few local governments and commerce departments promoted unmandated hour-earlier work schedule experiments during the summer without officially resetting clocks.

The Council on Economic and Fiscal Policy is expected to propose that the Japanese government begin studying DST in an attempt to help combat global warming. The former Japanese PM Shinzo Abe made a significant effort to introduce daylight saving time, but was ultimately unsuccessful.[32] However, it is not clear that DST would conserve energy in Japan. A 2007 simulation estimated that introducing DST to Japan would increase energy use in Osaka residences by 0.13%, with a 0.02% saving due to lighting more than outweighed by a 0.15% increase due to cooling costs; the simulation did not examine non-residential buildings.[33]

Jordan
Jordan UTC+2 observes daylight saving time from the last Friday of March to the last Friday of October.

Kazakhstan
Kazakhstan made a decision to stop observing DST in 2005, citing health complications as well as lowered productivity and a lack of economic benefits.[34]

Kyrgyzstan
Kyrgyzstan voted to stop observing DST in 2005 and remain on UTC+6 as Standard Time (which used to be Kyrgyzstan Summer Time), thus still saving energy.

Lebanon
Lebanon has the same rules as the EU Countries, starting on the last Sunday of March and finishing on the last Sunday in October.

Malaysia
Malaysia used DST from January 1, 1933, but discontinued in December 31, 1981 to replace Malaysian Standard Time.

Pakistan
Pakistan experimented with DST in 2002, going from +5:00 to +6:00 on the first Sunday in April at 00:00 to the first Sunday in October at 00:00. Pakistan has implemented DST again from June 1, 2008 to August 31, 2008, to meet the annual shortfall of 4 gigawatts of electricity instead of enforcing daily power cuts in households and factories.[35] The government later extended the schedule to October 31, which also included the holy month of Ramadan, which began in early September. In 2009 DST starts on April 15, and ends in November 1.

Philippines
The Philippines experimented with DST for short periods during the presidencies of Corazon Aquino (1986 to 1992) and Fidel Ramos (1992 to 1998). DST was primarily intended to help deal with the country’s energy crisis by minimizing the number of hours during which electric lighting was needed. On April 2006, the Philippine Department of Trade and Industry again proposed that DST be implemented to help deal with rising oil prices.[36][37]

South Korea
South Korea observed DST from 1948 to 1951, from 1955 to 1960, and from 1987 to 1988. South Korea does not currently observe DST. As of July 29, 2009, the South Korean government is considering re-introducing daylight saving time from April 2010.

Syria
Syria observed DST at UTC+3, in 2006 from 30 March until 21 September (a change from 30 September). Now, DST is observed from the last Friday of March to the first of November.

Taiwan
Taiwan implemented DST from 1945 to 1961, revoked DST from 1962 to 1973, reinstated DST from 1974 to 1975, and abandoned DST from 1976 onwards.

No DST in Asia

These countries or regions do not use daylight saving time:

* Afghanistan
* Bahrain
* Bhutan
* Brunei
* Cambodia
* China
* East Timor
* Georgia
* Hong Kong
* India
* Indonesia
* Iraq
* Japan
* Kazakhstan
* Kuwait
* Kyrgyzstan
* Laos
* Macau
* Maldives
* Malaysia
* Mongolia
* Myanmar
* Nepal
* North Korea
* Oman
* Papua New Guinea
* Philippines
* Qatar
* Saudi Arabia
* Singapore
* Taiwan
* Tajikistan
* Thailand
* Turkmenistan
* United Arab Emirates
* Uzbekistan
* Vietnam
* Yemen

Although DST is not used in South Korea, the government may bring it back in April 2010.

Europe

All countries in Europe except Iceland observe DST, and most change on the same date and time, starting on the last Sunday in March and ending on the last Sunday in October. Before 1996, DST ended on the last Sunday in September in most European countries; however in the United Kingdom and the Republic of Ireland DST ended on the fourth (which some years is not the last) Sunday in October. In the West European (UTC), Central European (CET, UTC+1), and East European (UTC+2) time zones the change is simultaneous: on both dates the clocks are changed everywhere at 01:00 UTC, i.e. from local times of 01:00/02:00/03:00 to 02:00/03:00/04:00 in March, and vice versa in October.[38] See also: European Summer Time and British Summer Time which includes a description of Double Summer Time.

Denmark
Although DST has been observed in Denmark for the past few decades and its observance will continue in accordance with EU orders, a national association against DST (Landsforeningen mod Sommertid) still exists.[39]

Iceland
With Iceland observing UTC all year round despite being at a longitude which would indicate UTC-1, the country may be thought of as being on continuous DST. Iceland’s high latitude means that sunset and sunrise times change by many hours over the year, and the effect of changing the clock by one hour would, in comparison, be small.

Italy
In its history Italy adopted DST several times on and off, beginning in 1916 till 1920, then again between 1944 and 1948 during and after WWII. A law approved in 1965, and entered into force the following year, made the application of DST mandatory in the whole country. Since 1996 DST is coordinated with the European Union .

Norway
In Norway, DST (locally known by the expression “summer-time”) was introduced in 1916, 1940–45, and 1959-65. The arrangement was controversial, and in 1965 the Norwegian parliament (Stortinget) voted to discontinue the practice. However, in 1980 DST was reintroduced, and at present (2010) Norway follows the European Union in this matter.

Portugal
In Portugal, DST (locally known by “Hora de Verão” (summer-time)) was introduced in 1916. In the years 1922, 1923, 1925, 1930, 1933 and from 1967 to 1975 the DST was not applied [41]. For many years the official hour in the Madeira Islands was Lisbon hour -1 and in the Azores Islands was Lisbon hour -2. Today, in the Madeira Islands the official hour is the same of Lisbon and in the Azores Islands is Lisbon hour -1.

Romania
DST was originally introduced in Romania in 1932 (between May 22 and October 2). Between 1933 and 1940 DST started on the first Sunday in April and ended on the first Sunday in October. The DST was abandoned in 1941, to be reintroduced in 1979. Until 1996, with few exceptions, the DST started at the end of March and ended at the end of September. Since 1997, DST has started in the last Sunday in March and ended on the last Sunday in October, per European Summer Time.

Russia
In Russia, daylight saving time was originally introduced on July 1, 1917 by a decree of the Russian Provisional Government,and clocks were moved one hour forward. It was abandoned by a Decree of the Soviet government five months later, clocks being moved one hour back again on December 27.

Daylight saving time was reintroduced in the USSR (Moscow Summer Time) on April 1, 1981, by a decision of the Council of Ministers of the USSR, and its practice continues into post-Soviet times. The changeover dates in Russia are the same as for other European countries, but clocks are moved forward or back at 02:00 local time in all zones. Thus in Moscow (local time = UTC+3 in winter, UTC+4 in summer), DST commences at 23:00 UTC on the day before the last Sunday in March, and ends at 23:00 UTC on the day before the last Sunday in October (note that “day before last Sunday” is not the same as “last Saturday” in a month where the last day is a Saturday).
[edit] Sweden

In Sweden daylight saving time was originally introduced on May 15, 1916. It proved unpopular at the time, and on September 30 in the same year, Sweden returned to year-round standard time. This situation continued for more than half a century.

On April 6, 1980, Sweden again introduced daylight saving time, and since then DST has been observed every summer in Sweden. Except for the introduction year 1980, daylight saving time has always started on the last Sunday in March. It ended on the last Sunday in September during the years 1980-1995, and on the last Sunday in October from 1996 onwards, following a unification of start/end dates of DST within the EU as well as in several European countries then outside the EU.

Five days before the reintroduction of DST in 1980, a major Swedish newspaper took the opportunity to publish an April fool’s joke on April 1, 1980. The joke claimed that DST had been introduced almost in secret with nearly no public information, that everybody was late everywhere, that hardly anyone really knew what the time was, and that there was chaos everywhere.

Switzerland
The last country in Europe to adopt DST in 1981 was Switzerland, because of the stiff opposition of the influential Swiss farmers’ lobby, who repeatedly stalled attempts by the Federal Assembly to legislate on the matter, and subsequently sponsored referendums to abrogate it. Since 1996 Swiss DST follows EU regulations.

Turkey
DST was introduced in Turkey in 1947, but suspended from 1965 through 1972. Since 1974, Turkey follows European Summer Time.
Turkey has started working to abolish daylight saving time from 2009 onwards, but due to technical reasons and (and not due to the opposition from the Turkish Foreign Ministry), has been postponed, to be abolished in 2011[43] Turkey proposes to adopt a new time zone in 2011: UTC+2:30 throughout the year (with no Summer Time).

No DST in Europe

These countries or regions do not use daylight saving time:

* Iceland
* Georgia

Oceania

New Zealand, Australia , Samoa and Fiji are current areas of Oceania that have DST.

Australia
Present situation

Currently, New South Wales, Victoria, Tasmania, Australian Capital Territory and South Australia apply DST each year, from the first Sunday in October to the first Sunday in April. The Northern Territory, Queensland and Western Australia do not observe DST.

History

Daylight saving was first used in Australia during World War I, and was applied in all states. It was used again during the Second World War. A drought in Tasmania in 1967 led to the reintroduction of daylight saving in that state during the summer, and this was repeated every summer since then. A trial season of daylight saving commenced in 1971 in New South Wales, Queensland, South Australia and Victoria. In 1972 NSW, SA and Victoria joined Tasmania in regular daylight saving. Queensland had daylight saving from 1989 to 1992.

Originally Tasmania alone commenced daylight saving on the first Sunday in October, while the other states began on the last Sunday in October and finished on the last Sunday in March, until 2008. From 2008/09 daylight saving has been extended another four weeks in NSW, Victoria, SA and the ACT, in addition to Tasmania, from the first Sunday in October to the first Sunday in April.

In Western Australia, four referendums in 1975, 1984, 1992 and 2009 have rejected DST. In 2006, the Parliament of Western Australia approved a three-year daylight saving trial to be followed by a referendum to decide whether DST should be put in place permanently. However, public opposition mounted during the first year of the trial, and the WA Nationals announced a public campaign to bring the referendum forward to 2007.[47] The trial continued until the referendum, held on 16 May 2009 The result was another rejection of DST, by a larger margin compared to the three previous referendums. Although as previously the suburbs of the state capital, Perth, supported the proposal, it was by a much narrower margin than before with significant swings against it in several areas, most notably in the East Metropolitan region. As a result, the Premier of Western Australia has said that the DST issue should not be considered for at least another 20 years.

The Northern Territory and Queensland do not observe DST. Queensland experimented with DST in the early 1970s, and again in the early 1990s, but it was abandoned after a majority of residents voted against it in a 1992 referendum. It continues to be a source of controversy, particularly in the highly populated south-eastern corner of the state which borders New South Wales, where DST is observed. The Northern Territory experimented with daylight saving in the early part of the 20th century. It was last used in 1944.

Fiji

Fiji reignites DST in 2009 starting on November 29 and ending on April 26, 2010.

Hawaii
Because of Hawaii’s tropical latitude, there is not a large variation in daylight length between winter and summer. Advancing the clock in Hawaii would make sunrise times close to 7:00 a.m. even in June (Most of the inhabited islands are located close to the west end of the Hawaii-Aleutian time zone, but Oahu, Kauai and Niihau are located more than 7 degrees west of the Hawaii-Aleutian time zone’s meridian and should, theoretically, be located in the next time zone to the west.) Hawaii did experiment with DST for three weeks between April 30, 1933 and May 21, 1933; there is no record as to why it was implemented or discontinued. Hawaii has never observed daylight saving time under the Uniform Time Act, having opted out of the Act’s provisions in 1967.

New Zealand
From 30 April 2007, DST begins at 02:00 NZST on the last Sunday in September each year, and ends at 03:00 NZDT (or 02:00 NZST as defined in the Time Act 1974) on the first Sunday in April.

New Zealand time, including DST, is used by several Antarctic bases that are supplied from New Zealand. This results in the oddity that the Amundsen-Scott South Pole Station sets its clocks an hour further ahead during the southern summer, when the sun is constantly above the horizon, than in the southern winter, when the sun is constantly below the horizon. The extreme geographic position of the base means that no possible adjustment of the daily activity cycle can have any effect on the amount of sunlight received during those activities. However, the arrangement presumably makes real time communications with New Zealand more practical, particularly in dealing with offices.

The New Zealandic dependencies of Cook Islands, Tokelau and Niue do not maintain DST. They are located the other side of the International Date Line and have 21-23 hours time difference to New Zealand.

Samoa
Samoa starts with DST in 2010, starting on the last Sunday in September and ending on first Sunday in April.

U.S. Territories
All U.S. insular territories with civilian government in Oceania, American Samoa, Guam, and the Northern Mariana Islands lie in the tropics, and do not observe DST.

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