How We Test Refrigerators
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Most people only think about refrigerators when it’s time to remodel the kitchen, or if the contents of the freezer start to melt.
Here at Reviewed.com, we think about refrigerators all the time, so we can help you choose the right one when it’s time to buy.
We’ve spent time with hundreds of refrigerators, and assess each one with a combination of lab-based tests and experiential evaluation. For more information on our testing methodologies, read on.
Refrigerator testing lab
How hard a refrigerator has to work depends on the environment it’s in. To ensure each refrigerator is tested under the same conditions, we test all fridges in a special chamber that is strictly regulated for temperature and humidity.
The settings for our refrigerator testing lab are a temperature of 72°F +/- 5°F, and a humidity of 50% +/- 15%.
Set up and Calibration
After unboxing the refrigerator, we unpackage and install all of the shelves, drawers, and other accessories. If a water dispenser and/or an icemaker exists, then we attach a cold water line. We plug the power cord into a Watts Up brand power meter, which measures electricity usage. Before testing begins, we allow the ice container fill and empty once to ensure that it is working properly.
Once the refrigerator is hooked up, we set the freezer and refrigerator temperature settings to those recommended in the use and care manual that came with the refrigerator. Typically, this comes in the form of an arrow or the word “recommended” indicating a preferred numerical temperature setting.
If the freezer and fridge temperatures are set with a thermostat, then we dial in the temperatures at 0°F and 37°F, respectively. Those particular temperature settings match those of international testing standards for refrigerators, and are ideal for storing frozen and fresh foods.
We fill the freezer to capacity with ballast—plastic containers that have each been filled with ~500 grams of water. Once that water is frozen, the setup replicates a freezer full of food. A full freezer operates more efficiently, since frozen food retains the cold better than air and helps keep temperatures down. It is also representative of how most Americans use their freezers.
We calibrate the refrigerator by allowing it to run for 48 hours. We monitor the temperature of the fridge and freezer carefully, and only start testing once the temperature has stopped rising or falling. Typically, once a fridge has correctly calibrated, it will set into a steady temperature pattern that cycles 0.1°F-0.3°F above and below the set temperature for the fridge, and 0.5°F-1.0°F for the freezer.
Once calibrated, each fridge undergoes testing for a minimum of 96 hours. In that time, we test the cooling speed of the freezer, the temperature value and consistency for both the fridge and the freezer, quantify the product’s ability to maintain food freshness, and assess the efficiency of the product.
We collect temperature data from the fridge and freezer using small data loggers called iButtons. Each one contains a thermocouple, memory, and a battery. Once programmed, they continuously record temperature data.
We place one iButton each inside five plastic containers half filled with a methylcelluose mixture. This gelatinous mixture is used in refrigerator testing all over the world because it has the heat-retaining characteristics similar to lean beef.
The iButtons are positioned to sit at the exact middle of the methylcellulose mixture, which allows us to measure the internal temperature of food inside a fridge, rather than the air that passes around it.
Three methylcellulose packages go in the fridge and two go in the freezer. In the fridge, one container is placed on the bottom shelf on the door (roughly at crisper height), while the other two are placed in the main cavity of the refrigerator. One is at roughly middle height, and the other is located on the top shelf, with each of them at two distinctly different depths (distance from the front) in the fridge.
These locations represent where the most fragile food goes: dairy or beverages on the top shelf shouldn’t ever get close to freezing, leftovers on the middle shelf should never be warmer than 41ºF, and condiments on the door will taste funny if temperatures fluctuate too widely.
In the freezer, the methylcellulose containers replace two of the pre-existing Tupperware containers filled with water.
During the first 24 hours, the methylcellulose mixtures slowly settle into the set temperatures.
We measure how long it takes for the iButton to cool to 32°F from room temperature. Faster freezing times result in better food preservation and a higher freezing test score; slower cooling can cause a loss in food flavor and an unpleasant texture, and results in lower freezing test scores.
Temperature Value & Consistency
Once the first 24 hours of testing have elapsed, we will then score the temperature value and consistency of the fridge and freezer based on the iButton data collected over the next 72 hours. For the temperature value, we look at how closely each refrigerator matches the desired temperature of 37°F. For freezers, the desired temperature is 0°F; this is based on the IEC standard for refrigerators.
The ability to hit and maintain a certain temperature is important for maintaining the shelf life of your food. Food items that undergo repeated temperature changes of more than 1°F-2°F can affect the flavor or taste of foods and beverages (such as wine). Additionally, if your fridge temperature gets higher than 40°F, then there’s a good chance that bacteria will grow quickly on foods exposed to the air. This is especially not good for meat products, where the types of bacteria that grow in climates warmer than 40°F tend to be those that make you spend a lot of extra time in the bathroom.
For temperature value test, the more consistently the fridge or freezer maintains a temperature of 37°F and 0°F, respectively, the higher the score. For the temperature consistency test, we look at the temperature cycling: if the gap between the temperature maximum and minimum values is significant, then the consistency score will be low. Conversely, if that temperature gap is very small, then that product will have a high temperature consistency score.
In addition to looking at the temperature state of the fridge and freezer, we also quantify how effectively fresh food is preserved in the crisper drawer. The ‘freshness’ is actually tied to the humidity values; the longer a vegetable drawer can maintain a high moisture content, the more slowly your delicious kale or carrots will dehydrate and spoil. Too much moisture, however, will cause your veggies to rot.
To measure freshness, we use a ball of floral foam to calculate water loss over time. First we measure the weight (in ounces) of the floral foam when it is completely dry. Then, we add ten times the foam’s weight in water to the foam ball, and then re-weigh it. We place the wet floral foam in the vegetable/crisper drawer of the fridge, and remove it from the fridge once each day (throughout the 72 hour testing period) to be weighed.
We look for a slow change in weight over time, as that’s indicative of a crisper drawer that retains just enough moisture to keep food from drying out, but not so much that food may rot. Rapid water loss will result in a low humidity score, while slower water loss means that your vegetables will retain their water and freshness for a longer period of time, and will result in a higher humidity score.
An extra benefit of the humidity test is that it requires us to open the door twice a day to remove and then replace the floral foam. While people open their refrigerators much more often than twice a day, opening the door twice a day helps us to see how the temperature performance of the fridge is affected by opening the door and exposing the interior of the fridge to warmer air.
Additionally, some fridges may automatically enter a power-saving vacation mode when the door isn’t opened for days. Our tests ensure that that condition never occurs.
We collect power usage over the course of the 72-hour test period. The power usage accounts for the running of the refrigerator, as well as one fill cycle of the icemaker, if one exists.
The efficiency scoring is two-fold: firstly, when testing is completed, we assess the energy usage in a day, and then project that usage out to a yearly energy cost. Secondly, the daily energy use is calculated in proportion to the capacity of the entire refrigerator.
Unlike most appliances, refrigerators are always on, so it is important that they run efficiently, regardless of their size. Large refrigerator units with a low electricity draw and low yearly costs will score very well; smaller refrigerator units with a large electricity usage and higher energy costs are very inefficient, and will score poorly.
We are very proud of our lab tests, but we know that they don’t fully reflect the experience of owning an appliance. With our subjective assessments, we judge the product from an experiential standpoint in two separate categories: the overall storage space of the refrigerator, and the usability of the refrigerator.
In the course of the objective testing, it becomes apparent that some refrigerator and freezer configurations are more convenient than others. Some products have shelves in inconvenient places, or do not have the flexibility to make room for taller food or liquid items.
To quantify this, we measure the effective capacity (also required for the efficiency calculation) for both the fridge and the freezer by measuring height, width, and depth of the usable space on a given shelf or drawer. Unlike how manufacturers measure fridge capacities, we take into account any obstructions such as user interfaces or icemakers/water dispensers. For instance, we won’t measure gaps between a shelf and an interior wall as “usable space”.
The closer the effective storage space is to the total capacity claimed by the manufacturer, the higher the storage score is. If the reported capacity is much larger than the effective capacity we measure in person, then the storage space score is very low.
Lastly, we score the customizability of a shelf or section configuration by looking at the shelves and section dividers. How many of the shelves can be removed and placed in different locations? Are any of the shelves retractable? Can the configuration in general accommodate differently sized food products? Does the fridge come with any accessories that can be placed in different places, like ice cube trays or egg holders? These are the types of questions we look at to determine the product’s customizability.
The more flexible the shelf and tray configuration, the higher the customizability score. If there is very little room for shelf adjustment, and there is no place for large or tall food items, the customizability score will be low.
We incorporate our experience with the product into the usability scores. To give our readers all of the details about a given product, we describe our day-to-day interactions with this refrigerator: is it easy to open the fridge and freezer doors? Is it difficult to change the set temperature in the freezer? If the refrigerator has an icemaker or a water dispenser, how easy is it to operate those features? If tomato sauce leaked out all over the bottom shelf, is it especially difficult to clean it out? These questions and more get answered and folded into the usability scores for each refrigerator that we test.
By breaking a product down into its objective performance and its subjective experience, we are able to give our readers all the information they need to make a wise purchasing decision when the time comes. To stay on top of the latest new products, check our library of refrigerator reviews. To see our short lists for the highest scoring refrigerators, check out some of our Best Right Now articles, such as the Best Refrigerators, Best Stainless Steel Fridges Under $2000, and the Best Beer Fridges.