The time change, between winter time and summer, exists in many countries and has been implemented mainly for reasons related to energy consumption. The first large-scale change of time dates back to the First World War, then this measure was abandoned before being reintroduced as in France or kept but adapted as in Canada.
In France, for example, the time change was abandoned in 1945 and then reintroduced after the 1973 oil crisis to promote energy savings. Researchers at the Swiss Federal Laboratories for Materials Testing and Research were interested in office buildings and wanted to know if the main reason for the time change, saving energy, was still a valid reason more than 50 years after its introduction.
Opponents of the time change argue that the energy savings achieved by turning on the lights earlier in the evening are now minimal, but the scientists who conducted the study believe that the savings can be substantial if we take into account the overall consumption of buildings and not just lighting. The scientists, who conducted simulations of heating and cooling requirements with and without time change for different climate regions, published their results on the Institute of Physics Science website in January 2023.
They considered not only the current climate, but also different climate scenarios through 2050 to incorporate the impact of climate change on a building’s energy consumption. In a laboratory press release, Massimo Fiorentini, a researcher at the Urban Energy Systems laboratory, indicates that switching to daylight saving time can reduce the cooling energy needs of an office building by up to 6%, provided that air conditioning is reduced or turned off when the offices are empty.
At the same time, heating requirements can increase by 4.4% due to an earlier start to work in the morning. But since much more cooling energy is consumed than heating in the summer, the time change has an overall positive influence on a building’s energy balance. For the researchers, the maximum level of energy savings is estimated at 3% and varies according to the scenarios and the climatic zones, but the savings are real. The researchers also point out that other measures can save on energy consumption in an office building, such as changes in behavior or adaptation of working hours.
According to a study commissioned for France by the Agency for the Environment and Energy Management, in 2006 the time change saved 470-gigawatt hours for lighting and 210 gigawatt hours for thermal uses. In 2009, the savings for lighting amounted to 440 gigawatt hours, which corresponds to a reduction in CO2 emissions of about 44,000 tons, and for thermal uses, the savings are close to the 2006 level.
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