When we go to work or to the store, do we leave the air conditioning on or off?

The optimal use of air conditioning during summer months requires careful consideration of both comfort and energy efficiency. When temperatures rise above 30 degrees Celsius, many people instinctively reach for the thermostat and set it to its lowest setting. However, the discomfort of summer often stems not just from heat, but primarily from high humidity levels. In poorly ventilated spaces, sweat evaporates more slowly, making it harder for the body to cool down, while the air feels heavy and stuffy. Modern air conditioning units do more than simply cool a room, they also dehumidify, filter the air, and can distribute cold air more evenly. Experts recommend keeping the difference between indoor and outdoor temperatures within six to eight degrees. If the outside temperature reaches 34 degrees, it is advisable to set the air conditioner to 25 or 26 degrees rather than 20. Clean filters, proper shading, and regular maintenance are essential for ensuring the unit operates efficiently and safely. Proper selection of settings can help prevent excessive noise and reduce electricity consumption. According to experts, air conditioners consume significantly less energy when they run continuously at a higher temperature compared to operating briefly at lower settings with maximum power. The Slovenian Consumer Association recommends setting the temperature to a maximum of 24 to 25 degrees Celsius. The golden rule states that the temperature difference between indoors and outdoors should not exceed six to eight degrees. Even when the thermometer reads 33 degrees outside, the air conditioner should not be set below 24 degrees. Each degree above 25 degrees can result in savings of six to eight percent in annual electricity costs. A large temperature difference can also harm health. Closing windows and doors while the air conditioner is running helps maintain indoor comfort. Covering windows with blinds or curtains prevents passive heating from sunlight. Ventilation should be done early in the morning or late in the evening when the outside air is cooler. During the hottest parts of the day, limit the use of stoves and ovens, as these appliances emit a lot of heat into the space. A room fan can also contribute to comfort by moving air around, creating a sense of freshness without consuming much energy. Regular maintenance ensures the air conditioner runs efficiently and safely. A well-maintained unit consumes less electricity, lasts longer, and does not endanger health. In humid environments, internal components of the air conditioner can quickly develop microorganisms and mold, causing unpleasant odors and allergic reactions. Air filters can be cleaned with tap water, but more complex tasks should be left to professional service technicians. Regular service typically starts at around 70 euros. When purchasing a new air conditioner, always choose an energy-efficient model. Cheaper models often consume more electricity, and the difference in energy consumption between the best and worst-rated models can amount to nearly 190 euros per year. Portable air conditioners are a last resort, as they operate less efficiently and produce more noise. Deciding whether to keep the air conditioner running or turn it off when you're away is a common dilemma. Some people believe that leaving the unit on saves energy because it avoids reheating the space upon return. Others prefer turning it off immediately once the desired temperature is reached and restarting it only when needed. According to experts, neither approach is always ideal. The most rational use depends on how long you will be away, the type of air conditioner you have, how well the apartment is insulated, and the humidity level. For short absences, such as going to the store, it is recommended not to turn off the air conditioner. American experts suggest allowing the thermostat to manage the unit's operation. For longer absences, raising the temperature slightly can be beneficial. The U.S. Department of Energy recommends increasing the temperature by about four to six degrees. This can save up to ten percent of annual heating and cooling costs, although actual savings depend on climate, insulation, and building characteristics. It is important to distinguish between traditional and inverter air conditioners. Traditional units operate on a "on-off" principle, running the compressor at full capacity until the space cools sufficiently, then shutting off and restarting when the temperature rises again. Inverter units adjust the compressor’s power after initial cooling and maintain temperature with significantly reduced energy consumption. Even with an inverter unit, it is generally more efficient to raise the temperature slightly when you will be away for several hours. Setting the air conditioner too low does not make it cool faster. An air conditioner does not cool a space more quickly if set to 16 instead of 24 degrees Celsius. It will simply run longer and overcool the space unnecessarily. Humidity and insulation play crucial roles in determining the effectiveness of cooling. Complete shutdown of the air conditioner is not always the best solution, especially in hot and very humid conditions, as prolonged absence can increase the risk of condensation and mold formation. In dry climates, the space may warm up more easily without significant issues. Energy consumption is influenced by the building itself. Well-insulated apartments retain cooled air longer than poorly insulated ones, such as attics or rooms with large windows facing the sun. Energy consumption cannot be estimated solely based on the number of hours the air conditioner runs. A unit that operates for fewer hours at lower power can consume less electricity than another that must run constantly at full capacity. Maintenance is also vital for reducing energy usage. Dirty filters restrict airflow and force the unit to work harder, leading to increased energy consumption. Experts recommend regular cleaning or replacement of filters, checking condensate drainage, and inspecting seals. Simple measures such as closed windows, lowered blinds, or shaded curtains can significantly reduce heat gain and thus the need for cooling.