Daylight Saving Time can actually increase energy use by boosting air conditioning demand during warmer months.

The traditional argument for Daylight Saving Time (DST) dates back to 1916 when Germany adopted it to conserve coal during World War I. However, modern research suggests these savings have disappeared due to the widespread adoption of climate control technology. A landmark 2008 study by researchers at Yale University and the University of California, Santa Barbara, analyzed electricity usage in Indiana—a state that provided a unique natural experiment by adopting statewide DST only in 2006.The study found that while lighting demand decreased, the increased need for cooling in summer and heating in spring and fall resulted in a net increase in energy consumption. Indiana households experienced a 1% increase in annual electricity bills, totaling approximately $9 million in additional costs. The researchers noted that the extra hour of evening sunlight occurs when outdoor temperatures remain elevated, placing substantial strain on residential air conditioning systems.Similar findings emerged from Australia during the 2000 Sydney Olympics when DST was extended. Data showed that the shift did not reduce total electricity demand and actually increased peak loads in some regions. These studies challenged the assumptions behind the Energy Policy Act of 2005 in the United States, which extended DST with the expectation of energy savings. Today, many experts argue that the environmental and financial benefits of the practice are outdated in a world dominated by HVAC systems rather than incandescent lighting.