Should you turn your air conditioner off when you’re not at home? It depends

Most people believe that turning off the air conditioner when they are not home saves them money. Researchers at the University of Colorado Boulder tested that theory.

The research team used an energy model that simulates heat transfer and the performance of air conditioners to address the question everyone wants answered. Does turning off your air conditioner when you're not home actually save energy?

They found that this depends on the type of cooling system in your home, the climate of the area you live in, and how your home is constructed.

Researchers have found that when a house gets hot, the process of heat transfer slows down. Eventually, when the internal temperature equals the external temperature, there is zero heat transfer at equilibrium.

Studies show that extreme heat reduces the cooling effectiveness of your air conditioner, so turning it off during the hottest part of the day can improve the overall efficiency of your system. These effects mean there's no easy answer to whether you should turn on the air conditioner all day or wait until you get home from work.

Using U.S.-developed energy modeling software developed by the National Renewable Energy Laboratory to analyze residential energy use, the University of Colorado Boulder team used energy use in a 1,200-square-foot fictional home. I investigated some test cases for

During the study, the researcher considered his three temperature strategy scenarios in his two temperate climate zones of Arizona and Georgia. One was that the internal temperature was set at a constant 24.4 degrees Celsius. During an eight-hour work day, he had a temperature rise of 89 degrees Fahrenheit (31.6 degrees Celsius) in one second. This is a "retreat". In the final example, we lowered the temperature to 89 degrees Fahrenheit (31.6 degrees Celsius), reducing the working hours by 4 hours per day.

They looked at three different AC technologies: single-stage central air conditioners, air source central heat pumps (ASHP), and mini-split heat pump units. A central AC unit is typical of what most people use today.

They found that even if the air conditioner temporarily peaked to recover from the rise in room temperature, the overall We found that it consumes less energy. Researchers have shown that this can result in energy savings of up to 11% on an annual basis using traditional central air conditioning. 
 

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