"Refrigerator... performance? Is that even a thing? I mean, they're just big ice boxes, right?" Wrong!
For most consumers, the two most important factors when buying a new refrigerator are "Will it fit inside my kitchen?" and "How does it look?" Important considerations, but hardly the end of the story.
Why do we bother with all this performance stuff? Well, refrigerator performance affects the taste, texture, and longevity of your food in very noticeable ways. Food that you paid for! Fridge performance also affects your electricity bill, which, for owners of highly inefficient machines, means more money down the drain.
So while it's tempting to buy the biggest, newest, and... stainless steel-est fridge you can find, you're better off taking the time to understand the ins and outs of refrigerator performance. And the best way to do that is to—ahem—read some reviews. But as a primer, let's go through the five most essential performance factors.
In order of importance, moisture retention comes first. It's the most noticeable difference between a good fridge and a bad one.
We're mostly talking about the moisture retention of the produce drawers here. These drawers need to capture and hold onto the moisture of your produce because every drop of water that escapes is juice and flavor that will never reach your taste buds. In other words, if you've ever blamed your grocer for dry carrots, it's time to apologize—and start blaming your fridge.
Even a perfect fridge would allow some moisture to escape, since that's what prevents mold from growing. We've found that a perfect fridge allows about a tenth of a gram of moisture to escape per hour.
Produce sensitive to ethylene gas (a byproduct of ripening found in tomatoes, bananas, avocados, etc.) must be stored in a place that allows this gas to escape, which is why you see crispers with sliding scales and "Low Humidity" settings. Bear in mind, though, not all crisper drawers are the same.
Every fridge gets cold (some colder than others, and we test for that too), but how steadily an internal temperature can be held over time is another factor separating excellent fridges from lousy ones.
Our imaginary perfect fridge would help food maintain an internal temperature of exactly 37°F at all times across its upper shelves. That's cold enough to keep milk from spoiling too soon, but warm enough to avoid freezing it.
In the real world, temperatures inside good fridges can fluctuate by ±3°F, and that's fine. But if food temperatures start wavering above and below 32°F, all that freezing and unfreezing can dramatically worsen the texture and taste of your food. Likewise, if the temperature stays above 42°F for too long, you risk accelerated spoilage.
That said, a little extra warmth around the crispers can actually be better for produce. So we record temperatures at three different sites within the fridges we test, and we always warn you if any spots are too hot or too cold.
The situation is even more serious in the freezer, where consistent temperatures are both more important and more difficult to maintain. Our perfect freezer would maintain 0°F at all times, in all areas. Temperature shifts in the freezer cause sublimation (when ice changes directly into vapor with no liquid stage), and that's the primary cause of freezer burn. Freezer burn will of course make stored meat—or pretty much anything—taste terrible.
The Freezing Test
Now that we understand how important consistent freezer temperatures are, we can appreciate why faster freezing times are desirable. Bringing room-temperature food down to freezing is just one long, sublimation-causing temperature fluctuation.
Our perfect freezer would flash-freeze food without any time passing whatsoever, ignoring Newton's Law of Cooling to keep your food undamaged upon thawing. But in the real world, where physics apply, this is impossible. The best modern freezers we've tested can accomplish this in a little over an hour, but most models need an hour and a half.
Power Loss Insulation
We're based in Boston, so the phrase "in the event of a power outage..." is kind of like saying "next winter, when the power goes out again, like it always does..."
Anyway, in the event of a power outage, a good fridge with thick insulation and a good seal should be able to stave off spoilage—especially for frozen food.
Our perfect fridge would store food at exactly the same temperature forever, regardless of power and regardless of the properties of entropy. But in the real world, we expect frozen foods to stay frozen for 36 hours without power, and we test this using the highly scientific process of... unplugging the fridge. This is a pass / fail test, and virtually every fridge passes.
If there's one thing we've learned by testing all these appliances over the years, it's that every manufacturer's efficiency claims aren't always representative of real-world use. It's not a vast conspiracy, but it is a function of products performing differently in your kitchen than they do in labs certified by the Department of Energy.
Depending on the temperature of your kitchen, your fridge might have to work harder than it does in a lab. And if you're constantly using the ice maker, expect even higher power bills. In general, however, most larger fridges will cost the average American home between thirty and forty dollars a year to power, and the most inefficient models can run you much more.
We think it's important to report this, since it helps keep the purchase price in perspective. For example, if you're hoping to save a hundred bucks up front by buying a less efficient fridge, those savings could be lost to extra utility costs in just a few years.
Because fridges come in different sizes, it's hard to compare energy use across the board. That's why we calculate electricity usage as a ratio of kilowatt hours per cubic foot. Some of the newest models, released after updated EPA guidelines, have been clocking in at as low as 0.05 kWh per cubic foot, and that's great.
"Big, cold box." Hah!
Now that you know a bit more about proper fridge performance, why not dig deeper? The rabbit hole is this way....