Failing to clean an air conditioner’s filter can push energy consumption up by as much as 30%, information from economic journalist José María Camarero. The effect varies with the filter’s condition and the system’s design, as well as how long it operates. Restricted airflow can make a unit run longer to deliver the same cooling. In Spanish homes, where air conditioning is a lifeline when temperatures soar, this costly mistake takes only minutes to address.
Speaking on ‘La Tarde’ on COPE, Camarero explained that dust and debris clogging the filter force the unit to work harder and longer to reach the desired temperature. The extra runtime can increase electricity use and put additional strain on system components. He recommends cleaning the filter at least once a year, and more often if the unit runs for many hours daily. The Instituto para la Diversificación y Ahorro de la Energía (IDAE) also emphasizes regular maintenance to preserve an appliance’s efficiency and lifespan.
How Much Can You Save?
Actual savings depend on the model and how dirty the filter is, as well as how many hours the air conditioner operates. The U.S. Department of Energy puts potential energy savings from cleaning or replacing a clogged filter at around 5% to 15%. The result depends on the circumstances, so it is not a guarantee for every home. In Spain, where summer heatwaves are increasingly common, efficient operation can make a difference to household bills, particularly as electricity prices fluctuate.
Thermostat Settings Matter
Another common error is setting the thermostat too low in hopes of cooling rooms faster. Camarero warns that programming the unit to 18°C does not make it cool a room faster once the system reaches its available capacity. Instead, it can keep the unit running longer to reach the lower target. The estimate that each degree below 24°C adds roughly 8% to the bill, and that dropping from 24°C to 18°C could mean nearly 50% more energy use, should be treated as a rule of thumb rather than a fixed outcome. Cooling demand also depends on outdoor temperature and humidity. Sunlight, insulation, heat from appliances and occupants, and the air conditioner’s controls also matter, including whether it is inverter-driven. The IDAE recommends keeping the thermostat between 24°C and 26°C for comfort and efficiency, especially when dressed appropriately for the season.
Depending on the unit’s efficiency and the home’s insulation, as well as hours of use, Camarero estimates that air conditioning can add between €20 and €60 per month to a household’s electricity bill. That range is illustrative, not a set charge: the actual cost depends on the system’s power draw and operating time, along with the household’s electricity tariff. These figures highlight the importance of sensible thermostat settings and regular upkeep.
Airflow and Room Comfort
Small adjustments to airflow can also make a difference. Camarero suggests angling the air conditioner’s vents upward so cool air descends and spreads through the room. Directing airflow around the space can help reduce cold spots, along with the temptation to set the temperature unnecessarily low.
Keep the Heat Out
Simple habits beyond the unit itself can ease the burden on your air conditioner. Closing blinds and lowering awnings help block direct sunlight and limit heat entering the home. The IDAE advises ventilating homes at night or early in the morning, when outside air is cooler, to refresh rooms without overworking the system.
Combining these strategies with regular maintenance and sensible thermostat use can reduce energy consumption and costs during Spain’s hottest months. For more on how air conditioning habits affect other aspects of daily life, a recent analysis of the impact of starting your car with the AC already on examines the hidden costs of cooling.
