Both bottom-mount and side-by-side refrigerators are less energy efficient than a conventional top-mount model. However, bottom-mount freezers use less energy than side-by-side appliances.
According to the US Department of Energy , a bottom-mount freezer without an ice maker averages around 551 kilowatt-hours a year, less than a side-mount refrigerator's 6057 kilowatt-hours. Appliances with through-the-door ice makers average 560 and 608 kilowatt-hours respectively.
Refrigerators with a bottom freezer offer the convenience of an eye-level refrigerator and make it easy to reach vegetables and other bottom-shelf foods. However, the freezer on a bottom-mount appliance is harder to reach.
These appliances are best for people who use their freezers rarely. Side-by-side models make both refrigeration and freezer compartments easy to access, but their narrow doors can make it hard to store a pizza box or other wide objects.
Some features, such as in-door water and ice dispensers, are readily available in side-by-side refrigerators. According to Consumer Reports, these machines also frequently feature individual temperature and humidity for the bins and rapid ice-making features.
Bottom-mount freezers tend to be more basic and can be hard to find with special features. Some refrigerators with a bottom-mounted freezer have French doors on the refrigeration compartment for easy access, but these appliances can be costly and hard to find.
Side-by-side refrigerators may not provide as much space as their capacity suggests. According to Consumer Reports, only about 65 to 70 percent of the space inside a side-by-side appliance is usable.
The tall narrow compartments also make it hard to reach objects at the back of the fridge. You may need to buy a larger side-by-side appliance to get the same amount of storage space as in a top- or bottom-mount refrigerator.
Bottom-mount appliances have more usable space inside, but can be difficult to find in narrow widths.