A colder fridge setting is not always better; adjusting it by 1°C could reduce energy use by 8 to 11%

Most of us assume that colder is safer and better, so we turn the dial down a notch “just in case.” But a lab study titled ‘Factors Affecting Refrigerator-Freezers Energy Consumption’ published in the ASEAN Journal on Science and Technology for Development found this small habit adds up fast. Researchers at the University of Malaya tested two full-size, frost-free refrigerator-freezers and found that energy consumption increased 8.8% to 11.3% for each degree the thermostat was set colder.

The experiment behind the claim

The study tested two types of household appliances: one had a total capacity of 492 liters, whereas the other had a capacity of 460 liters. Both units were subjected to all possible temperatures ranging from the warmest to the coldest while keeping room temperature at 26°C constant. With the decrease in thermostat position, energy consumption increased steadily. According to the study, changing from the warmest to the coldest position, a shift of several degrees, resulted in a daily energy consumption increase of 1.363 kWh and 1.046 kWh for the two units, respectively.


Room temperature matters even more than the thermostat

In the study, the thermostat was not the biggest factor. The researchers found that if they adjusted the room temperature from 15°C to 31°C, but kept the thermostat and door constant, the energy consumption increased by about 141 Wh per day for one model and 102 Wh per day for the other, for every degree the room temperature rose. Overall, room temperature had a bigger effect on energy use than the thermostat setting, the study notes. This finding is also in line with other recent research. In a 2018 study of room air temperature in 235 Australian homes published in the journal Energy Efficiency, it was found that in real households, room air temperature alone accounted for around 75% of a fridge’s total energy use. So if your kitchen is next to a window, an oven, or gets direct afternoon sun, that may affect your electricity bill more than the thermostat setting.

What about opening the door constantly?

If you're the type to open the fridge and stare at its contents mid-scroll, you might think this is the biggest energy drain. It may not be. The same lab tests showed that each door opening added only about 12.4 Wh a day for one model and 9 Wh for the other, the smallest effect of the three factors studied. This suggests that for most people, worrying about how often the door is opened matters far less than getting the thermostat and room placement right.

What temperature should you actually use?

The U.S. Department of Energy's Federal Energy Management Program states that a temperature of 36°F to 40°F (about 2°C to 4°C) should be maintained in the fridge, and -5°F to 0°F (about -21°C to -18°C) should be maintained in the freezer. It also notes that lower temperatures mainly use more electricity.

What this means for your kitchen

This does not mean you should ignore food safety, but there is a difference between "cold enough" and "too cold." If your fridge is already set a notch or two lower than the recommended range, because of old myth, old habits, or a desire for freshness, dialing it back slightly can shave a noticeable amount off your monthly energy use, without impacting how long your food lasts. Where the fridge is placed is just as important as the dial setting, with research showing that room temperature has an even bigger effect. A fridge in a poorly ventilated corner, in direct sunlight, or next to a stove has to work harder regardless of the thermostat setting. Checking your fridge's setting and location takes only a moment, but this research suggests it could shave a noticeable amount off a bill you pay every single month, all year round.