Across Spain, many people lower their air conditioning settings to 19°C or even 16°C after a hot day. Yet choosing a very low target does not cool a room faster and can keep the system running longer. Endesa guidance warns that during heatwaves, a very low setting can keep the compressor operating for longer, raising electricity consumption and adding wear to the equipment. The effect depends on the unit and conditions, but sustained heavy use can increase the risk of faults during the busiest part of summer.
An air conditioner does not work like a car accelerator: setting a lower target does not make it deliver cooling faster. When the thermostat target is far below the current room temperature, the system may run longer in an effort to reach it, consuming more electricity. Heat-pump air-conditioning systems can deliver several units of thermal energy for each unit of electricity used, but performance varies with outdoor conditions and the temperature required. Daikin, as reported by ESEFICIENCIA, gives an example of some reversible systems supplying about 4 kWh of heat or cooling for every 1 kWh of electricity; that ratio is not fixed across all equipment or operating conditions.
Specialists recommend maintaining a stable indoor temperature between 24°C and 26°C for efficiency and comfort, while keeping the difference between indoor and outdoor temperatures within 12°C. A moderate setting can provide relief without demanding as much from the system as an unusually low target. A large indoor-outdoor temperature gap can also increase energy use, while abrupt changes may be uncomfortable, particularly for children and older people.
Proper maintenance is impressive for reliable operation. Endesa recommends regular filter cleaning, along with checks of drainage and cooling components. It also advises monitoring refrigerant levels and keeping the outdoor unit clear of dust and debris. Dirty filters and obstructed airflow can reduce performance, so neglecting routine care may increase consumption and the likelihood of malfunctions.
Spain’s growing use of air conditioning is reflected in household electricity data. A Selectra analysis of the IDAE’s SPAHOUSEC III study puts air conditioning at 5.3% of household electricity consumption, compared with 2.3% in 2010. The measurements covered October 2021 to September 2022, and the studies did not measure consumption in exactly the same way, so the figures are best read as a longer-term trend rather than a like-for-like annual comparison. The same analysis found that the Mediterranean climate zone accounts for close to two-thirds of residential air-conditioning electricity use, underlining how cooling costs vary with climate and the length of the cooling season.
Cooling demand is also becoming a wider energy-system issue during heatwaves. Energy Digital, citing ABB and industry data, reported that French electricity demand rose by almost 20% during a peak two-week period in June 2026; the report also described space cooling as the fastest-growing source of energy demand in the buildings sector. For households, the practical steps remain straightforward: use a moderate thermostat setting and limit heat entering the home with shading; keep equipment clean and well maintained. Spain’s government has also introduced temperature guidelines for public buildings and businesses to encourage energy savings. With energy prices volatile, avoiding unnecessarily low settings can help families manage bills while reducing prolonged strain on their air-conditioning systems.
