Moving clocks forward in spring brings lower energy consumption - study

With the start of daylight-saving time in Israel on Friday at 2 a.m., discussions break out – as they do every year both in politics and in the wider society  –  about whether or not we should eliminate the time change.

Opponents argue that time change impacts our health, for instance through sleep disturbances. Proponents, on the other hand, often bring forward the argument of saving electricity because of longer days, which means that less artificial light is needed.

“That was the original intention behind the introduction of Summer Time. From our point of view, however, it makes sense to look not only at the impact on electricity savings in lighting but on the overall energy consumption of a building,” said Sven Eggimann, a researcher of next-generation urban infrastructure systems at the University of Zürich’s Swiss Federal Laboratories for Materials Science and Technology. Together with his colleague Massimo Fiorentini and other colleagues, he has determined whether and how the time change affects heating and cooling energy consumption.

The scientists’ hypothesis was that employees start their work an hour earlier in summer due to the time change and leave the office earlier in the afternoon. Since most of the cooling happens later in the afternoon, this can save energy.

The assumption behind this is that in an empty office, the cooling can be reduced or even turned off completely. As buildings become more intelligent, this would be relatively easy to accomplish in the future.

They published their findings in the peer-reviewed journal Environmental Research Letters under the title “Climate change shifts the trade-off between lower cooling and higher heating demand from daylight saving time in office buildings.”

Testing their hypothesis

To test the hypothesis, the researchers simulated the heating and cooling energy used with and without Summer Time for different climatic regions based on data from various office buildings in 15 American cities. They took into account not only the current climate but also future climate scenarios up to the year 2050. This is crucial, as climate change has an enormous impact on a building’s energy consumption. In another study, the researchers found that in future, Switzerland’s demand for cooling could match the one for heating due to climate change.

The results of the current study should please the proponents of Summer Time. “Switching to daylight-saving time can reduce an office building’s cooling energy by up to almost 6%. At the same time, heating demand can increase by up to 4.4% due to the earlier start of work in the morning. However, since much more cooling than heating energy is needed in summer, the time change has a positive overall effect on the energy balance of a building,” summarizes Fiorentini.

Across the different climate zones and scenarios, the overall energy savings varied – peaking at around 3%, but they were evident everywhere. Although this result only relates to office buildings in the US, it also provides valuable insights for Switzerland, as the climatic conditions are comparable for several of the simulated climate zones.

“Our study shows that time change can contribute to climate protection. In the discussion about eliminating daylight-saving time, policymakers should therefore not only consider the electricity savings in artificial lighting, but also the impact on the energy balance of office buildings as a whole,” concluded Eggimann. “At the same time, the researchers emphasize that the time change is only one of many ways to influence the energy consumption of a building.

Technical improvements of the buildings, behavioral changes and a general adjustment of our working hours can also contribute to energy savings and thus CO2 reduction – regardless of whether or not we change the time every six months.”

The Environment and Climate Change portal is produced in cooperation with the Goldman Sonnenfeldt School of Sustainability and Climate Change at Ben-Gurion University of the Negev. The Jerusalem Post maintains all editorial decisions related to the content.

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