Turning off fridge at night saves 19.8%, study finds

Switching off the fridge nightly: Savings and risks

A consumption meter, a timer, and a domestic refrigerator. These three components formed the basis of a months-long home experiment to determine what happens when power is cut to the appliance that, initially assumed, consumes the most energy in a household during seven early-morning hours. The first round of measurements yielded specific results: the counter dropped from 2,473 over two days to 2,021 with the fridge off for seven hours daily. A 19.8% reduction. In euros, the author’s calculation suggested just over €12 per year, negligible compared to the waste caused by a poorly adjusted fridge.

Then came the twist. Adjusting the setpoint temperature by a few degrees caused consumption to plummet by 30% immediately, making the nighttime shutdown less sensible. The storage temperature, not plugging and unplugging, proved to be the real lever.

How much does a fridge consume and how much can you save by turning it off?

The records, keeping units as noted, are as trinc: 24 hours of normal operation left the counter at 877, with the interior at 8 degrees. Unplugging it for 12 hours and remeasuring showed 731, with the temperature already at 13 degrees after the outage. Comments accompanying these data suggested the disconnection added worthwhile savings.

Direct comparison warrants skepticism. Consumption measured over 48 hours versus 24 hours are not comparable magnitudes, and starting and ending internal temperatures do not always align. Without equalizing conditions, subtraction is misleading. Scale objections also matter: turning off a modem at night does not offset the cost of an air conditioning unit, so savings depend entirely on which device is disconnected.

The thermostat already stops the compressor: Why timers add little value

An argument cited by several participants dismantles half the idea: fridges come standard with a thermostat that cuts the compressor once the target temperature is reached. If standby consumption—electronics, interior light—is marginal, an external timer adds almost nothing. The machine doesn’t need reminders on when to stop, and the invention of shutting it off at fixed times is largely reinventing the wheel.

What actually tilts the balance is adjustment. Raising the fridge’s setpoint temperature reduces compressor work steadily without forcing long stops. The same rule applies to freezers: maintaining them at -28 degrees is unnecessary unless one intends to preserve Walt Disney.

Recommended fridge temperatures

Between 4 and 8 degrees lies the range typically cited for cold food preservation. Some health references, used for storing bodies in refrigeration chambers, set the maximum at 7 degrees. The experiment’s author claims contents remained cold at 8 degrees; another participant expressed serious doubts about this temperature and the 13 degrees, considering it a risk to the cold chain.

The margin between 6 and 8 degrees is wider than it seems, representing the real source of savings. The less the compressor fights external heat, the less energy is consumed.

Defrosting and the cold chain: Risks nobody measures

Turning off the fridge for hours isn’t free. Defrosting in many models evaporates accumulated water using compressor heat. If the appliance remains idle too long, the compressor cools down, fails to evaporate water, and may suffer damage. This warning, offered by a participant mid-conversation, is significant.

Ice buildup above five millimeters requires manual defrosting, taking care not to use sharp objects that puncture circuits. Then there’s the obvious: breaking the cold chain forces food disposal, eating up bill savings via the bin. Some recommend testing in winter, when ambient outdoor temperatures help maintain cold.

Insulating the fridge and other saving methods

Beyond the plug, the list of measures is extensive. Insulating the exterior casing with polystyrene and thin lining is cheap and, according to proponents, could bring a modest fridge closer to a good energy class without replacing it. Keeping the condenser ventilated—that rear coil—is mandatory for heat dissipation. Separating food into transparent plastic drawers allows opening only necessary trays without losing all cold at once.

Logic extends to other devices. Replacing old 500-watt computers with low-consumption machines—a Mac Mini hovers around 30 watts at full performance, a modern iMac uses 1 watt at idle, according to those who switched—is viewed as a direct path; another participant questioned these figures. Switching bulbs to LED pays off quickly, they argue. Some add robot vacuums and alarm meters to the list, though not everything self-funds. Swapping a computer used four hours daily for leisure isn’t worth it; doing so for one running 12 hours is, per their reasoning.

The domestic trial ended where doubts begin. According to reports, accumulated savings—thermostats, night shutdowns, new equipment—dropped bills from €200 every two months to €40. The experiment’s author admits uncertainty regarding whether long stops shorten appliance life; no one has measured that aspect.