Today, we know that switching to summer time does not lead to any noticeable energy savings. According to the Federal Association of Energy and Water Management of Germany(BDEW), we consume less electricity for lighting on sunny summer evenings, but correspondingly more electricity for our evening leisure activities or for air conditioning systems that run for longer periods of time. In addition, more and more energy-saving lamps are finding their way into households these days and electricity consumption for light is falling steadily.
The introduction of summer time has always been associated with the hope of reduced energy consumption.
Benjamin Franklin has already formulated the idea of reducing the energy consumption caused by the use of artificial light in the evening and at night by shifting the rhythm of the day forward.
Summer time was introduced in several european countries during the First World War with the aim of saving energy to benefit the war economy. Shortly after the war it was mostly abolished again. In the following time there were only limited attempts with daylight saving time in individual states - until the Second World War broke out and Germany introduced a summer time again - hoping to save energy. Again, after WW2, summer time was abolished in most countries.
The next big impulse to establish a daylight saving schedule was the oil crisis in the 70s. France reintroduced summer time in 1976. As a result, most central european countries followed with some delay - Germany in 1980. Even more important than considerations of energy consumption, however, was the desire to achieve a harmonized regulation between the individual European countries so as not to hinder the growing internal market. Finally, in 1996, the summer time regulations within the EU were completely harmonized.
Actual impact on energy consumption
The postulated reduction of energy consumption by means of DST has always been subject to controversy and could never be proven.
Since energy consumption depends on a large number of factors, only a very small effect could have been expected.
In fact, summer time seems to favour increased energy consumption.
A time change can indeed lead to a lower use of artificial light. However, this is usually countered by an increased consumption of heating energy, which is caused by bringing the main heating time forward. The consumption of energy due to the increased use of air conditioning in summer, which is caused by the fact that the days are 'longer', as well as increased consumption due to leisure activities also eats up the effect of the lower consumption of artificial light.
This effect has recently been intensified by the dramatically reduced energy consumption of modern light sources such as LEDs.