The start of daylight saving time this weekend will bring divisions between scientists.
When clocks go forward by one hour, as they do every Spring, debates occur about whether or not we should eliminate daylight saving time. Its opponents argue that the clocks changing impacts our health due to sleep disturbances. However, those in favour say that longer days save electricity, therefore, lowering our artificial energy consumption.
“That was the original intention behind the introduction of daylight saving. 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,” explained Sven Eggimann from Empa’s Urban Energy Systems Lab.
The team at Empa conducted research to determine whether and how time change affects heating and cooling energy consumption. The results, ‘Climate change shifts the trade-off between lower cooling and higher heating demand from daylight saving time in office buildings,’ was published in Environmental Research Letters.
Testing a hypothesis based on the effects of daylight saving time
In their paper, the researchers stated: “The original intention of daylight saving time was to save energy required for artificial lighting. However, this one-hour shift in working hours also impacts the current and future heating and cooling demand of buildings, which is yet to be thoroughly investigated.”
Therefore, the team created a hypothesis that stated that employees start work an hour earlier during daylight saving time, meaning they also leave the office later in the afternoon. As most cooling happens later in the afternoon, these measures can significantly save energy.
As office buildings become more energy efficient, the cooling naturally reduces or turns off completely. To test this statement, the researchers simulated the heating and cooling energy used during daylight saving time and compared it with results outside of this time.
To test their hypothesis fairly, they analysed different climatic regions based on various data from office buildings in 15 US cities. To include the influence of climate change, they considered the current and future climate scenarios up to the year 2050, which is crucial due to climate change’s impact on the energy consumption of buildings. For example, in one of their previous studies, Empa researchers found that Switzerland’s cooling demand could match the heating demand due to climate change.
What did the study conclude?
The results of the new study highlight the benefits of daylight saving. Massimo Fiorentini, who conducted the study along with Eggimann, stated: “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 an overall positive effect on the energy balance of a building.”
Across the different climate types and scenarios, the overall energy savings varied slightly. On average, they peaked at around 3% in most regions, but the amount of energy saved was evident in all areas.
Despite only detailing results in the US, this study helps to analyse energy-saving results in Switzerland, as the climatic conditions are comparable for several of the simulated climate zones.
Protecting the climate with energy-saving measures
Eggimann said: “Our study shows that time change can contribute to climate protection. In the discussion about eliminating daylight saving time, policymakers should consider the electricity savings in artificial lighting and the impact on the energy balance of office buildings as a whole.”
When assessing the impact of policies targeting the shift in working routines, climate change, and future heating and cooling demand will play a distinctive role – a warmer climate was shown to generally reduce potential relative savings for office energy demand resulting from a shift in working hour patterns, whilst achieving similar absolute reductions.
Finally, the researchers emphasised that daylight saving time is only one of many methods that can be used to lower the energy consumption of buildings. Technical improvements, behavioural changes, and a general adjustment of employees’ working hours can also contribute to energy savings and, therefore, reduce CO2 emissions regardless of whether the time changes every six months.
“What this study clearly shows, however, is that in the discussion surrounding daylight saving time, policymakers should revisit the original policy intention of saving energy by considering energy demand for space heating and cooling whilst considering climate change,” the researchers concluded.
