Standard time and summer time, is "double track" still convenient? How much does it save?

Before arriving at the result of the investigation, it should be remembered that solar time indicates the standard time (also called conventional civil time or standard summer time) associated with the reference meridian of a country's time zone: in Italy it corresponds to UTC+1 and is in force in the autumn and winter months. Daylight saving time, on the other hand, is the convention by which clocks are brought forward by 60 minutes (to UTC+2 in Italy) for a limited period of the year, mainly with the aim of reducing energy consumption linked to artificial lighting in the evening hours.

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During the hearing, the eighteenth-century origins of summer time were recalled, which then found its first regulatory application during the First World War: in 1916 the United Kingdom adopted British Summer Time and the United States introduced, in 1918, Daylight Saving Time, two ploys to "gain" an extra hour of light in the late afternoon. In Italy, summer time was introduced for the first time, for the same war reasons, in 1916. Going forward in time, summer time became a tool for saving energy: by moving the time forward to make better use of natural light, the hours of artificial lighting in the evening hours were reduced.

During the Committee hearings in the Chamber, a brief was presented by Terna S.p.a., manager of the national electricity transmission network, based on the analysis of three scenarios: the current regime with double seasonal change, a hypothetical permanent solar time regime and a hypothetical permanent summer time regime. "From the analysis carried out with reference to the period 2015-2026, and with a projection to 2030 which takes into account the growing diffusion of non-programmable renewable sources, it emerged that the electricity demand curve relating to the permanent summer time scenario is always the most contained of the three scenarios considered, although the three curves have undergone a progressive approximation over the most recent years", we read in the results of the survey. The reason, "most likely", is the greater energy efficiency of lighting systems compared to the past.

Terna has estimated that for 2026 the current regime (seven months of summer time) would lead to a reduction in consumption of approximately 302 GWh, to which a further approximately 160 GWh would be added if summer time were also extended to the winter months, for an overall annual benefit of approximately 462 GWh (according to the data released by Terna in January 2026, the overall national electricity requirement is equal to approximately 311.3 TWh in 2025).