Climatology, Energy, Energy comsumption, Power systems

For what serves the daylight saving time?

What is the finality of daylight saving time? Saves energy and/or other purpose? It is this post’s subject.

Summer solstice

This schedule adjust was created to take advantage of summer solstices. Starts in June 21 or 22 in north hemisphere and December 21 or 22 in the south hemisphere.

The daylights are longer during a solstice. These are the solstices maps of north and south hemisphere respectively.

Energy consumption are saved with extra natural lighting, because don’t need to turn on the lamps.

Consumption peak

A consumption peak is reached when people arrive at their homes after work. Consumption peaks can overload the system, with schedule adjust the peaks are reduced. This is a graphic of Cemig, company from Minas Gerais state, Brazil, which shows the comparison between the consumption with daylight saving time (red) and without it (blue).

This is another comparative graphic of energy consumption in southeast and south Brazil. In orange with daylight saving time and in yellow without this adjust.

Daylight saving time in the world

This map shows the regions of planet which adopt the daylight saving time. In blue, are the places that actually use the daylight saving time, in orange it no longer used and in red are the countries that never adopted.

In the north hemisphere, watches are turned forward one hour in the months of March or April and in September and October are turned backward one hour.

In the south hemisphere, one hour is turned forward in months of November or October and one hour turned backward in the months of February, March or April. The beginning and end dates depends on country`s arbitrary decision. Why some countries stopped using daylight saving time? The main cons arguments are:

  • Some studies show that the energy saving is very low to justify this seasonal time adjustment;
  • The time change affects the people’s biological clock.

Personally I don’t mind adapt to time change, is still necessary to reduce consumption peaks. The daylight saving time was implemented when most part of energy consumption came from lighting, today we have many devices with other functions. In the summer, increases the use of air conditioner and fans. What do you think? Still need the daylight saving time?


About Pedro Ney Stroski

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