Clock turning has a long history. A main argument for this has always been that if human activities are better adapted to the available daylight, energy can be saved. But does it actually work?
Claim: Summer time saves energy.
Rating: Not assigned.
Facts: As early as the end of the 18th century, the American scientist and statesman Benjamin Franklin proposed reducing the consumption of candles by getting up and going to bed earlier. He didn't want to change the time for that. But his intention gets to the heart of the argument used to advocate for the introduction of daylight saving time: we better align the period of human activity with usable daylight in order to save energy and lighting costs.
Against the background of scarce energy resources during the First World War, daylight saving time was introduced in the German Reich in 1916. Much of Europe did likewise. After the war ended, most countries returned to normal time. This was repeated during and after the Second World War. From 1950 there was no more daylight saving time in Germany.
Around the oil price crisis in 1973, the discussion about a renewed introduction returned. When the GDR informed the Federal Republic in October 1979 that it would introduce daylight saving time from 1980, this followed. Since 1996, all members of the EU have changed their clocks at the end of March and the end of October.
And what did that bring, specifically related to saving energy? "How much energy is actually saved by switching to summer time cannot be precisely quantified, because: The conversion leads to lower consumption in one place and higher consumption in another," summarizes the Federal Environment Agency (UBA). On the one hand, daylight is used better during the summer and electricity is saved in the evening hours. On the other hand, because of the earlier rising in the cooler morning hours in spring and autumn, more heating energy is consumed.
Basically, the share of artificial lighting in electricity consumption has fallen significantly in recent years due to the improved efficiency of modern light sources. According to the Federal Environment Agency, a household requires by far the most energy for heating. This accounted for around 70 percent of the total energy consumption.
In 2016, the Office for Technology Assessment at the German Bundestag came to the conclusion in an overview analysis "that the effects of summertime on energy consumption can be both positive and negative, the extent and extent of which depend heavily on the climatic, economic and cultural framework and are almost certainly very small in most cases". Overall, the scientific knowledge regarding the aspect of energy consumption is limited, incomplete or contradictory.
Nothing fundamental has changed since then. In individual countries there were further evaluations of energy saving through summer time - for example for Slovakia (2018) or the Serbian capital Belgrade (2018). However, these are also of limited significance and, if at all, assume very little potential for savings. The analysis for Belgrade comes to the conclusion that the relative number of hours in which offices have to be air-conditioned can be reduced by twelve percent as a result of summer time.
And how would it look in terms of energy technology if perpetual summer time were introduced in Europe – which some people would like? An analysis by the German economist Korbinian von Blanckenburg from 2016 on possible electricity savings in private households showed that the most savings could be achieved with a permanent summer time. However, there is a paper from 2021 for Turkey, which abolished clock turning in 2016 and has stuck to its daylight saving time. The scientists concluded that this daylight saving time strategy did not lead to measurable energy savings.
