Demand-Side Flexibility for Household Electricity Bill Reduction in Ireland for Cooking, Dishwashing, Tumble-drying and Electric Ovens
This study analyzes the potential financial benefits of shifting household appliance usage to off-peak times under Irish Time-of-Use tariffs, finding that while modest annual savings and minor peak demand reductions are possible, current incentives are insufficient to drive widespread behavioral change without stronger mechanisms or enabling technologies.
Original paper licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). This is an AI-generated explanation of the paper below. It is not written or endorsed by the authors. For technical accuracy, refer to the original paper. Read full disclaimer
In Ireland, as in many modern nations, the electricity grid faces a unique challenge: it must be built to handle the busiest moments of the day, even though those moments are fleeting. The cost of keeping the lights on is not determined solely by how much power a home uses over a year, but by the highest spike in demand that occurs at any single time. When everyone turns on their ovens, heaters, or dryers at the same time in the evening, the system requires expensive infrastructure to cope, and those costs eventually appear on every household's bill. To manage this, energy companies have introduced pricing plans that charge more for electricity during these busy "peak" hours and less during the quiet "off-peak" times. The idea is simple: if people can shift their heavy appliance use to the cheaper times, they save money, and the grid becomes more stable. This concept, known as demand-side flexibility, relies on the willingness of households to change their daily habits in exchange for financial reward.
A team of researchers from University College Cork set out to test whether this promise holds true for the average Irish home. They focused on four common appliances that consume significant power: electric ovens, dishwashers, washing machines, and tumble dryers. Using data from a national survey that tracks how people actually use energy, combined with current electricity rates from the country's largest suppliers, the researchers built a detailed model to calculate exactly how much money a family could save. They did not rely on theoretical ideals alone; instead, they looked at real-world usage patterns to see what happens when a household tries to move just one cycle of each appliance from a busy evening slot to a quieter time.
The results of this investigation were surprisingly modest. In a highly optimistic scenario where a household perfectly shifts one use of each of the four appliances every single week from a peak time to a cheaper off-peak time, the annual savings range from about €5 to €44, depending on which electricity supplier the family uses. When the researchers adjusted their model to reflect a more realistic, representative Irish household—one that does not shift every single instance perfectly but follows typical usage patterns—the potential savings dropped significantly. In this more grounded scenario, the annual savings for shifting usage to off-peak times fell to between €0.63 and €5.43 per year. Even if a family were to shift their usage to the cheapest night-time rates, the maximum saving in a realistic scenario was only around €5.43.
These figures suggest that the current financial motivation for changing behavior is quite weak. For a household with an annual electricity bill of approximately €1,600, saving less than €6 a year is unlikely to encourage people to alter their daily routines, such as waiting until late at night to start the dishwasher or cooking dinner at a different time. The researchers noted that while cooking is the most common activity during peak hours, it is also the most difficult to shift because meal preparation is tightly linked to family schedules and social habits. Although people expressed interest in shifting appliance use in surveys, the actual money on offer does not seem strong enough to turn that interest into action.
The study also looked at the broader impact on the national grid. If a small portion of households, say 5 percent, were to successfully shift their usage, the reduction in peak demand would be meaningful, potentially lowering the national peak by 0.5 percent to 2.0 percent. However, achieving this requires a level of participation and behavioral change that current incentives do not appear to support. The researchers found that while shifting appliances helps, the effect is limited when driven solely by the existing price differences between peak and off-peak times.
The picture changed slightly when the researchers considered technology. They modeled the use of a home battery storage system, which charges up when electricity is cheap and releases power when it is expensive. A household with a standard 4-kilowatt-hour battery could save approximately €150 per year by using this system. While this is a much larger saving than shifting appliances alone, the upfront cost of buying and installing such a battery is high, ranging from €2,000 to €4,000. This means it would take a family between 12 and 28 years to earn back the cost of the battery through savings alone, ignoring maintenance and inflation.
Ultimately, the study concludes that while demand-side flexibility is a valuable tool for the energy system, the current time-of-use tariffs in Ireland are not strong enough to drive widespread change on their own. The financial rewards for simply moving a washing machine or an oven to a different time of day are too small to overcome the inertia of daily life. To make a real difference in reducing peak demand and lowering bills, the researchers suggest that stronger financial incentives, better enabling technologies, or a focus on larger flexible loads like electric vehicles and heat pumps will be necessary. For now, the promise of saving money by shifting a few household chores remains a small benefit rather than a life-changing opportunity for the average Irish consumer.
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