Do we use less energy during daylight saving?

In early 2019, the European Parliament voted to end daylight saving time (DST) from 2021. It is a subject that has been debated for decades in many parts of the world, and the decision wasn’t clear cut in Europe, with some countries happy to see the end of DST, others preferring to continue with it.

As the COVID-19 pandemic continued into 2021, the parliament overturned its decision as governments confronted bigger problems and greater priorities. Further complicating the debate came with Brexit and the possibility the United Kingdom would not follow Europe, creating more time-zone angst among neighbours and other countries in the region.

Opponents say DST disrupts circadian rhythms and can contribute to serious health risks like heart attacks, while many farmers have opposed DST, making an already early start to the day even earlier to sync with others in the market and retail cycle. Supporters say the extra hour of daylight can have a range of benefits, from increased opportunities for retailers, to more time for exercise.

One of the reasons for adopting DST in decades past was the idea that countries (or, in Australia’s case, the states) would save energy during the longer daylight hours in the warmer months. By extending daylight time by an hour, the idea was that energy consumption would be lower for consumers as there was less reliance on power for things like lighting until later in the day. Australia followed other countries in adopting DST during World War I to conserve energy.

But does the idea stack up today? Household energy consumption has changed significantly in just a few decades with a big uptake of home cooling, while many homes and businesses have ditched the power-hungry incandescent light globes for more efficient led and fluorescent products.

New South Wales, Victoria, South Australia, Tasmania and the Australian Capital Territory observe DST, while Queensland, the Northern Territory and Western Australia don’t. For the state and territories that observe it, it begins at 2 am on the first Sunday in October when clocks move forward and end on the first Sunday in April.

Economics lecturer in the Federation Business School Dr Quanda (Samuel) Zhang and a team of researchers have studied the impact of DST on energy consumption in Australia from 1998 to 2015, running extensive modelling on the data that they hope could be used by the European Parliament when DST moves back on to the agenda. This study was published in Energy Economics – a premier journal for energy economics and energy finance.

“Energy is a controversial topic, including here in Australia where there was no commitment made to increase 2030 emissions reduction targets at the Cop26 climate summit. This got us thinking about our energy usage in Australia and whether daylight saving time made a difference to energy use,” Dr Zhang said.

“We also knew Europe was planning to end daylight saving time. The idea of DST is to save energy, so we have looked at this in our research with the evidence that we gathered from Australia data.”

The researchers found with their modelling that when clocks are moved forward by one hour for DST, electricity consumption increases when temperatures are high, and cooling is widely used. This increase in demand for cooling outweighs the gains from less lighting. Air conditioner penetration has increased from 35 per cent to 65 per cent in Australia over the study period.

Taking the data that considered electricity consumption across all Australian states and the timing of DST implementation over the study period, the researchers then applied the modelling to individual EU countries.

“The simulations are quite relevant to Europe, and we hope this data will be considered when the EU Parliament decides on DST,” Dr Zhang said.

“We show that countries including Germany, the Netherlands, Sweden and the UK would benefit from adopting DST because of their relatively lower electricity demand. Other countries like Greece, Spain and Portugal would experience higher electricity consumption with DST. There are quite different scenarios for countries.

“Overall, our simulations show that DST will be costly in countries with higher summer temperatures and higher levels of AC penetration.”